EML2322L TA INFORMATIONAL ARCHIVE

Quick Links (Table of Contents)

Introduction

Design Guides

Bandsaws

Milling Machines

Lathes

Sheetmetal Equipment

Welding Shop

CNCs

Fasteners

Threading

Metrology

Control Boxes & Electrical

Project Motors & Miscellaneous

Commonly Manufactured Parts / Office Hours

Miscellaneous

Introduction / Purpose of Archive [RETURN TO T.O.C.]

This page should be thought of as the appendix to the TA notes and training materials used in the course, in that it contains supplementary information TAs should know, presented in a graphical manner. As you read these points, write down questions to ask during the TA meetings / training sessions. Items in black are common knowledge TAs need to understand their first semester working in DML. Items in red are less common, but still important information TAs need to understand to work effectively in the Senior Design Lab or Student Shop. Please submit ideas for additional points here.

Design Guides [RETURN TO T.O.C.]

1. Power Transmission (Hub) Design Guide. Familiarize yourself with the considerations for properly designing hubs for use transmitting power.

2. Motor Mount Design Guide. Familiarize yourself with the considerations for properly designing brackets for mounting motors and other components.

3. Sheetmetal Design Guide. Familiarize yourself with the considerations for properly designing sheetmetal parts.

4. Fasteners Design Guide. Familiarize yourself with the considerations for properly selecting and using fasteners.

5. 3D Printing Design Guide. Familiarize yourself with the considerations and restrictions for 3D printed part manufacturing in DML.

6. AWJ Design Guide. Familiarize yourself with the guidelines and design tips for AWJ manufacturing in DML, as well as the requirements for submitted drawings.

7. DFM Tips. Familiarize yourself with the DFM principles introduced in DML.

8. DFM Examples. Familiarize yourself with examples of poorly and well designed parts using the DFM principles introduced in DML.

Milling Machines [RETURN TO T.O.C.]

1. Power feed doesn’t function. Occasionally one of the power feed units on the mills doesn’t function because someone accidentally deactivated the power switch underneath the unit.

2. DRO doesn’t update as table or saddle moves. The occasional power surge will cause the DRO to freeze, and the fix is to simply re-zero each axis.

3. Switching between HI and LO range. As a TA you will need to be proficient switching the mills between HI and LO range.  This is not trivial, so the first time you do it you MUST have Mike or a TA present to ensure you do it properly. The following photos showing the right and wrong way of doing it should help. When switching speed ranges it is always necessary to gently rock the spindle back and forth to allow the teeth on the gears in the gearbox to properly engage. The first photo depicts the milling machine fully engaged in HI range, the second photo shows the machine not fully engaged in HI range. The third photo shows the milling machine in neutral (this can be noted by the ability to freely rotate the spindle).  The final photo shows the milling machine engaged in low range (the spindle will be very difficult rotate by hand). Until comfortable switching between ranges, always visually compare the orientation of the range selector lever to those on other machines before turning it on, to ensure that it is fully engaged.

4. Power drawbar doesn’t function or makes loud noise when retracting spindle. Occasionally enough moisture accumulates in the air lines supplying the milling machines to prevent the pneumatic drawbar controls from functioning. The solution is to cycle the controls a few times (IN and then OUT) until they begin working.  Additionally, sometimes the drawbar will make a loud rattling noise when the spindle is raised to the uppermost position while running.  This noise is caused by a sticky pneumatic piston that engages the drawbar during tool changes.  The solution is to remove the metallic black dust cover on the top of the unit and apply some WD-40 lubricant to the outside of the piston so it once again moves easily without sticking.  When applying the WD-40, cycle the piston manually by pressing it downward and releasing several times.

5. Fixing power drawbar after a student fails to lock spindle before installing/removing tool. When someone tries to remove a tool without properly raising and locking the quill/spindle, the drawbar jams and must be fixed. If this happens and Mike is around, please ask him to fix it. Otherwise, the technique is to raise the spindle as far as it will go (it will likely not go all the way up, or it is not jammed), and apply approximately 30 lb of upward force to the quill handle while depressing the IN and safety buttons on the drawbar controls in short 1-2 second bursts. With each burst the quill should raise a little, until it is all the way to the top of its travel and the quill/spindle lock can be properly set.

6. Fixing speed control if student changes it while mill is OFF. When someone tries to change the spindle speed when the milling machine is not running, the adjustable width pulleys inside the gear head will pinch the drive belt, shortening its life. The simple solution is to try to return the speed adjustment dial to its previous position without turning on the machine. If you aren’t sure of the speed at which it was formerly set, just adjust the knob in the direction it easily moves until you feel increased resistance to rotation. This will be close to the position from which the student mistakenly adjusted it with the machine turned OFF.

7. Keyed vs. keyless chucks. We typically use keyless chucks on our mills and lathes because most people find them easier to use (in the past students pinched their fingers in the chuck key gears when using keyed chucks). However, keyless chucks are considerably more expensive and fragile than keyed chucks, and should therefore only be used with drills up to ½” in diameter. Above this size, collets (which are always best) or keyed drill chucks should be used. Keyed drilled chucks should also be used for any tools requiring additional cutting torque (such as hole saws) or any tools requiring reversing of rotation direction (such as taps).

8. Micro drill chucks. These are useful when drilling small holes (< Ø1/16”) where increased sensitivity to axial thrust force is necessary to prevent drill bit breakage. The unique ball bearing design allows you to provide the drilling force manually, as shown in the video below.

9. Annular cutters. Annular cutters are located in the top drawer of the first lathe cabinet (closest to the tall tooling cabinets behind the mills). The R8 mill arbors are either located in the drawer or in the black plastic tool caddy on the mill table. Select the desired size cutter from the cabinet and clamp on the Weldon (D-shaped) flat with the set screw in the side of the arbor. Use the 1/4″ Allen key to tighten the set screw on the flat on the annular cutter (be careful, as if your hand slips, it can collide with the cutter!). The Speeds and Feeds document shows how to calculate the cutting parameters for an annular cutter. Use copious amounts of oil with annular cutters and do not feel them too forcefully. Here is a video showing their use.

10. Workstops. Workstops are used to preserve X-axis zeros for multiple parts or operations (e.g. the Turner’s Cube), eliminating the need to re-zero each time an identical part is reloaded. Workstops are stored on each mill's spindle brake lever, on the front of each mill vise, and in the mill accessories cabinet behind the mills. The procedure for use is to install a workstop on the fixed vise jaw, set the initial zero on the part, machine the first part, and when clamping the next part against the workstop, the same X-zero is retained.

11. Spindle, saddle, and table friction locks. The mills have friction locks for the spindles, saddles, and tables. The friction locks keep the axes from moving under cutting forces. The spindle friction lock (first photo) should always be used, unless you are confident the threaded spindle lock is screwed up tightly against the quill stop.  The table (second photo) and saddle (third photo) friction locks should be used when performing drilling or boring operations requiring high precision or producing high cutting forces (e.g. when drilling holes large than ½”, when using annular cutters, when using a boring head, etc.).

12. Metric collets. In addition to the standard (imperial / inch) set of R8 collets located on each mill there is a set of metric collets located in the left grey metal cabinet.  These are primarily used for clamping endmills with metric sized shanks in the mills.

13. 5C collet blocks. The 5C collet blocks are located on the top shelf of the second tall mill tooling cabinet (from the lab door) in an acrylic box. The available two holders are square and hexagonal in shape and use 5C collets located in the gray cabinet in the NW corner of the lab by the AC unit. These collet blocks are used to cut opposing, square or hexagonal features on round parts (e.g. a hex head on a fastener or rod). Load the appropriately sized 5C collet into the collet block, insert the workpiece, and tighten the supplied collet nut using the spanner wrench. NEVER tighten down on an empty collet, as doing so will damage it. Here is a video showing how to make a hex on a piece of round stock using a 5C collet block.

14. Jig plates. Jig plates can be used when a workpiece is oversized for the table mounted vises or when a workpiece is oddly shaped. Our jig plates are located on the floor or shelf behind the TM-2 in the main lab or in the bottom drawer of the tooling cabinet in the student shop. To mount the jig plate, clamp the lower portion of the T-shape into the vise (2^nd). To mount the workpiece to the jig plate position the part as desired and use clamps (like the Kant Twist in the 4^th photo) to clamp the workpiece securely to the jig plate (5^th/6^th).

15. Machinist screw jacks. Sometimes you need to support the end of a flexible workpiece to resist the cutting forces when machining. Machinist jacks are used for this purpose.

16. Heavy-duty workstop. In situations where the part or workholding prevents the use of the previously discussed work stops, this type of workstop is mounted to the back of the vise and is adjustable via split shaft collars.

17. 5-axis workstop. This is another type of versatile workstop which works well in a variety of situations.

18. Alternative vise jaws. Depending on the shape of the part and machining processes involved in its creation, a variety of vise workholding jaws exist for different applications. These jaws can be found in the teal and beige cabinet located to the left of Mike’s office door. All jaws are installed using the same method of removing the two bolts that attach them to the vise.

a. Talon jaws. When a part leaves only a very small amount of material to clamp, the talons on these jaws will bite into 0.060” of the part with sharp knife-like edges. There are two styles of Talon jaws: one set for cylindrical parts and one set for rectangular parts; the orientation and distance between the grippers can be adjusted by moving the talons along the jaw.  Here's a good video showing their holding strength.

b. Taller & wider jaws. There are taller and wider jaws made of aluminum and steel to clamp larger workpieces of various dimensions.

c. Soft jaws.  For complex or difficult to hold parts the lab stocks aluminum soft jaws, which are machined to match the contour or geometry of the part(s) requiring machining.

d. Vee jaws.  Can be used like the smaller v-blocks to secure cylindrical workpieces in the milling machine in either the horizontal or vertical direction.

19. 1-2-3 blocks. These are so named due to their dimensions: 1”x2”x3”. Like parallels, these blocks are precision instruments and so can be used to ensure a part or tool set-up is parallel to a particular surface datum allowing for quick fixture and tooling set ups. These blocks also have threaded and thru holes so that allow them to be clamped to parts, fixtures, or machine tables.

Lathes [RETURN TO T.O.C.]

1. Southbend won’t turn on. Occasionally one of the Southbend lathes won’t turn on because the student using it previously activated the E-STOP button on the control panel above the headstock or activated the foot brake, which in turn activated the E-STOP circuit. The former is corrected by simply resetting the E-STOP button; the latter is corrected by lifting up on the foot brake pedal so it is no longer activating the switch. Another reason the Southbend may not turn on is because of the electrical service disconnect switch located on the backside of the headstock is turned off; rotate it to the “on” position to restore power to machine. The final reason the Southbend may not turn on is because of the chuck guard interlock switch, which sometimes needs adjustment.

2. Southbend power feed doesn’t function. Power feed rates on the lathes are adjusted by changing the blue and silver levers on the front of the headstock. There is a thread and feed chart that shows what combination of lever positions coincides with what feed rates. The feed rate levers on the Southbends can be changed while the machine is off or while it is running. Occasionally one of the power feed units on the lathes doesn’t function because the feedrate control levers on the front of the headstock are not fully engaged. If the silver handle isn’t fully engaged in one of the numbered slots the power feed will not engage (compare the center photo with the one on the right where the handle is engaged fully in the slot). If the handle doesn’t want to fully seat in the selected speed slot (typically LCS8W (0.007”/rev)) then rock the chuck slightly until the handle fully seats itself (right photo). The same applies for the blue lettered levers; if the selection handle is between two letters, the power feed will not function.

Here is a list of feedrates that are appropriate for common materials when using the lathes in our lab (assuming proper lubrication and part stiffness):

Material	Recommended HSS Speed, V [surface ft/min]	Recommended Feed, f [in/rev]
Acetal (Delrin)	250	0.010 and up
Aluminum and its alloys	250	0.004 – 0.014
Brass (360 free machining)	200	0.004 – 0.014
Bronze (high tensile)	100	0.004 – 0.010
Stainless steel (303 free machining)	40	0.004 – 0.008
Stainless steel (304 work hardening)	20	0.004 – 0.008
Steel (.2-.3 C)	100	0.004 – 0.008
Steel (.4-.5 C)	60	0.004 – 0.008
Steel alloys (300-400 Brinell)	30	0.004 – 0.008
Titanium alloys	20	0.004 – 0.008
* multiply surface speeds in table by 2.5 for carbide cutting tools *

3. Troubleshooting DRO errors. About once a year, one of the Newall DRO units on the Southbend lathes will come out of calibration and the X-axis motion displayed on the DRO will be incorrect. Here is a brief document explaining how to reset the configuration to the original settings.

4. Radius vs. diameter. The Southbend lathe DROs are configured to display part diameter, meaning if you zero the X-axis readout, move the cross slide in 0.100” and make a cut, you will reduce the part diameter by 0.100” (physically removing 0.050” off the part radius). Most lathes with DROs do this for convenience, so diameter measurements can be directly compared to the DRO display (i.e. if calipers show the part is 0.123” oversize, exactly that amount needs to be removed according to the DRO display).

On the Ajax lathe however, the cross slide vernier dial references part radius, so if you move the cross slide in 0.100” and make a cut, you will reduce the part diameter by 0.200” (physically removing 0.100” off the part radius). This is an important distinction to make when using (or instructing other students on using) the Ajax lathe, or you will remove twice as much material by accident!

5. Setting the carriage stop. An important protocol to decrease the possibility of running a tool into the chuck jaws is to ALWAYS set the carriage stop so the cutting tool can't come any closer than a ¼” from the face of the chuck jaws (1^st). The carriage stop is adjusted using an Allen wrench on the two fasteners located in the top of the stop (2^nd/4^th). On the newer Southbend lathe there is also a silver dial on the carriage stop that allows fine adjustment. It’s important to note the carriage stop will need to be adjusted to different locations for different tools and should be adjusted accordingly and never just relied upon. Always torque the carriage stop screws as tightly as possible with the normal Allen wrench.

6. Loading and removing tailstock tools. It is frequently necessary to change tailstock tools in the lathes. Common examples include when using larger drills, when loading endmills to produce counterbores, or when installing keyed-style drilling chucks to hold taps for rigid tapping.

To remove a tailstock tool on the Southbend lathe, securely hold the tool with your left hand (use a rag if it contains a sharp tool, like an endmill), and retract the tailstock quill until the tool is gently ejected.  This occurs where at the location where the quill color transitions from shiny metal to darker oxidized metal.  When reinstalling tools in the Southbend, you must extend the quill an additional ¼” beyond its extraction point, index the tang on the backside of the toolholder to be loaded, and then forcefully slide the toolholder into the tailstock quill.

To remove a tailstock tool on the Ajax lathe, engage the tailstock lock (so it doesn’t slide along the ways), securely hold the tool with your left hand (use a rag if it contains a sharp tool, like an endmill), and bump the backside of the tool using the knockout rod until the tool is forcefully ejected.  The Ajax will accept a tool in any orientation, so there is no need to phase tools before installing. If the toolholder you are installing contains a sharp tool, be sure to use a rag to protect your hands.

7. Taper shank drills. Large drills (> 0.5”) for the lathes are located in the fourth lathe cabinet from Mike’s door. These drills have tapered shanks that transmit torque and allow for quick installation. Depending on their size, these drills are made with different size tapers, which require adapters to fit a particular size tailstock. Once the appropriate adapter is selected, insert the drill into the adapter, and install the drill with adapter into the lathe tailstock in the same manner as the keyless chuck. After completing your drilling operation, remove the drill from the taper adapter with the wedge from the same drawer as the adapter (1^st) by inserting the wedge into the slot at the back of the taper adapter and apply upward force on the wedge until the drill is released from the adapter sleeve.  Tap the wedge on a piece of scrap wood, never on top of the gray laminate tabletops.

8. Endmill holders. The general term endmill holder refers to a toolholder that allows an endmill to be clamped using a set screw against the provided Weldon flat on its shank (providing positive mechanical engagement). When used in lathes, these holders have a morse taper geometry that is compatible with all lathe tailstocks. When loading/unloading an endmill holder containing an endmill, always use a rag to protect your hand from serious injury and do not touch the precision tapered portion of the toolholder because the moisture on your hands will cause it to rust.

9. Live and dead centers. Typically found on top of the lathe cabinet, live or dead centers are used to provide support to longer workpieces where deflection will cause poor dimensional accuracy and surface finish. A center is mounted in the tailstock (sometimes a center can be mounted in the headstock this technique is called “turning between centers”) and mates with a matching hole drilled by the appropriate sized center drill. A dead center (2^nd) is a center that does not freely rotate; when a dead center is engaged it produces friction between the center and the workpiece; to prevent friction welding a lubricant is placed on the end of the dead center.  A live center (1^st) rotates with the workpiece due to the inclusion of internal bearings to allow the end to rotate.

10. Skoda live center. This live center differs from the previously discussed centers due to the end being interchangeable between a variety of end styles and shapes (conical, inverted cone, and flat serrated).

11. Steady rests. Steady rests are used when cutting shafts with long length-to-diameter ratios. As seen in the following videos, they are used in conjunction with tailstock centers.

12. Reversible chuck jaws. To accommodate larger diameter workpieces, many lathe chuck jaws can be reversed to increase the allowable clamping diameter. Good chuck jaws have two halves: a master jaw that engages the scroll inside the chuck body (allowing the three jaws to open and close synchronously when adjusted with the chuck key) and a top jaw that bolts to the top of the master jaw and clamps against the workpiece (1^st). Most top jaws can be removed and rotated 180 degrees to clamp larger work. However, the factory hardened top jaws correspond with a particular master jaw, so be sure to match the number stamped on the jaw with number stamped on the chuck body (5^th).

13. Changing chucks. As explained in the next point below, there are a variety of chucks which can be mounted to the engine lathe spindles for use cutting different shape workpieces. Consequently, it’s necessary to know how to change chucks without damaging the irreplaceable precision ground spindles. As seen in this instructional video, the process requires good upper body strength and close attention to detail.

When removing the existing chuck mounted to the spindle, place a piece of wood on top of the ways to prevent damage if the chuck accidentally drops. Pieces of wood have been contoured to match the commonly mounted 8” chucks and can typically be found on top of the chuck cart. To separate an existing chuck from the spindle, take the smaller chuck key handle which fits the first ring on the spindle and turn the square pins from their initial position between the two “v”-notches to the notch at the 12-o’clock position releasing the locked pins. After all the pins are released the chuck will be able to slide from the mounting plate. Sometimes the chuck will need to be tapped with a plastic mallet to release it from the spindle taper.

When installing a chuck, cleanliness is critical. Use the air to blow off the spindle nose, and blow out of the mounting end of the chuck to be installed. Then use a new blue paper towel with a little oil on it to wipe off any remaining chips or debris from the mounting surfaces. Finally, when installing the chuck, be sure to not bump the precision ground surface on the face of the spindle nose. Remount the new chuck following the same procedure used for removal, being careful to lightly tighten the cam locks evenly to allow the chuck to sit flush with the end of the precision ground spindle.

Please do not change chucks without first obtaining permission from Mike.

14. Alternative lathe chucks. Located between the Hardinge lathe and the lathe cabinets is a large storage cart for the chucks available in lab. Included on this cart are three jaw, four jaw, six jaw, and collet chucks. Four jaw chucks allow clamping of non-cylindrical workpieces and are available in two types: scroll (all jaws move at the same time) or independent (each jaw moves independently of the others and has to be indicated for proper alignment). Six jaw chucks are ideal for clamping thin-walled materials like tubing due to the clamping force being distributed over six jaws, and prevent the material from being crushed when used correctly. Collet chucks are beneficial due to their safer design (no protruding jaws and can operate at higher speeds) and the fact that they don’t mar the workpiece surface like normal chuck jaws; however, collet chucks are limited in collet size (1-3/4” diameter) and only nominal size workpieces can be clamped (the stock can only deviate ±0.002” from the specified collet size).

15. 4-jaw chucks. 4-jaw chucks are useful on lathes because they can be adjusted for better accuracy than any auto-centering (scroll) chuck, they provide more robust workpiece clamping when roughing, and they allow oddly shaped parts to be securely clamped. The downside to 4-jaw chucks is they take longer to use because parts must be indicated to run true (“on center”), however, with a little practice the procedure is quite easy and even quite enjoyable. The first photo below links to a step-by-step procedure for indicating a part in a 4-jaw chuck and the second two thumbnails link to good videos showing the procedure.

16. Collet chucks. Collet chucks use collets similar to those that hold tools inside the manual milling machine spindle, but in this case they are used to hold precise workpieces in the lathe while very evenly distributing the clamping force around the entire perimeter of the workpiece. The most common collet sizes for manual machines are 5C and 3J. 5C collets are limited to Ø1-1/8” material and 3J collets are limited to Ø1-3/4” material; they are available for holding English and metric size workpieces; and blank “emergency” collets are available which can be machined to any desired size / profile. The workpieces used in collets must be within +/-0.002” of the nominal collet size or the collet can be damaged and the work will not be clamped properly. Collets are available in round, square, and hexagonal shapes.

17. Cutting tapers using the compound slide. Each of the engine lathes in our lab have an adjustable axis on top of the cross slide that is used to cut compound angles. Below are a few videos showing how to adjust the compound slide to cut a short taper into a workpiece.

18. Cutting tapers using the taper attachment. Longer tapers may be cut using the taper attachment found on the Ajax or one of the Southbend lathes.  Below are a few videos showing the process.

Commonly Manufactured Parts / Office Hours [RETURN TO T.O.C.]

1. Entstort Counterbore. When producing the 0.75″ counterbore for the Entstort wheel hub, DO NOT rotate the spindle slower than 250 RPM, as doing so when modifying a part that contains cross-drilled holes (e.g. the assigned wheel hub) can cause the chipload (and therefore the torque) on the endmill to suddenly spike and shatter the cutting tool.

2. Zeroing Blind Holes (e.g. Entstort Hub). To properly zero a drill bit when creating a blind hole, ensure you zero at the start of the full diameter (2^nd and 3^rd) of the drill and not on the tip or tapered portion (1^st). To set the zero for a blind hole, drill slightly past the tapered portion of the drill tip, retract the drill to the position where the full diameter is in the plane of the face of the part, and zero the Vernier dial on the axis hand-wheel.

3. Zeroing / Creating Blind Holes on the Mill. If you wish to create a blind hole on the milling machine, there are two common methods. The first is to set the zero height using the spindle and to adjust the depth stop using the ruler on the front of the quill housing or a pair of calipers for more accurate depths. The second method is to set the zero height using the spindle, adjust the depth stop so it is in contact with the quill stop, retract the quill, raise the table by the depth you wish to bore, and then use the quill handle to bring the quill stop back into contact with the depth stop.

INSERT PHOTOS SHOWING DEPTH STOP USED WITH INTERGRAL RULER AND DEPTH STOP USED WITH CALIPERS TO SET DEPTH

4. Polycarbonate Disc for Entstort Hubs. If you have trouble realigning the wheel hub in the lathe when creating the counterbore in the Entstort hub use the polycarbonate disc on the front shoulder and re-clamp in the lathe.

5. Re-aligning a Part (e.g. Wheel Hub Set Screws). If a student unclamps a part and needs to reinstall it to tap the side holes, it will need to be re-aligned vertically. An easy way to re-clamp the part is to insert the proper size drill bit into the existing hole, install the drill bit into the drill chuck, lower the quill handle to mount the part into the vise, and raise the quill handle to remove the drill bit.

6. Ultrathin Parallels. Sometimes we need to leave parallels under parts so they don’t slip down into the vise (when opposite sides are not very parallel or the part can’t be clamped too tightly). These two sets of 16 gage aluminum parallels are cut to the heights needed to hold one or two 3/16” thick workpieces for motor mount manufacturing. There is also a full set of ultrathin steel parallels in the left mill cabinet for other size workpieces. Notice the picture showing the Kant Twist clamp used to clamp two identical motor mounting brackets together. These clamps are located in the mill table drawers, and if used by students which don’t finish part manufacturing in one work session, they should only be allowed to keep ONE clamp on their parts until the following week’s lab (so we don’t run out of clamps).

7. Paint Paddles. When clamping a workpiece with non-parallel sides (anything greater than 0.003” out of parallel) insert a paint paddle against the moveable jaw to provide a complaint material on which to clamp. We also have ½ x 2” Delrin strips to use for the same purpose.

8. Reamers for Motor Shafts. We have reamers for each size motor shaft listed in the Motor Specifications Sheets. These reamers are stored in a clear labeled tackle box that sits on top if the lathe cabinets during the prototyping phase of the course. Be sure to clean and return the reamers to their plastic storage tubes and to the tackle box when finished using them so they do not get lost.

9. Cytron Hub Broaching (link to part drawing). The wheel hubs for the Cytron motors need to be broached to create the internal keyway used to transmit torque. The tools necessary to produce the keyway include the broach, broach bushing, shim, and ejection rod (1^st), which are all stored in the clear tackle box in the Motor Supplies drawer of the black TA toolbox in the rear room. To make the first broaching pass, insert the bushing and broach into the hub, apply oil, and use the arbor press to gently push the broach through the hub (2^nd, 3^rd). When doing this, make sure the broach remains co-linear with the hub’s axis (simply stop and adjust the arbor press ram if it does not). Next, repeat the process after adding the first shim behind the broach to cut the keyway to its final depth (4^th). Flip the hub over and repeat the process using the shim (5^th), or use a second shim to increase the depth of the keyway so the hub slides easily onto the motor shaft. Use the ejection rod to advance the broach all the way through the part (6^th). Be careful not to drop the broach, as it is made from heat treated HSS, which is very brittle and easily broken (as the student you are helping to hold the broach before pushing it the remainder of the way thru the hub using the ejection rod).

10. Cytron Hub Modification. In some cases the snap ring and shaft that protrude from the backside of the wheel hub will interfere with the drive wheels. If that’s the case or there’s another reason the motor shaft needs to be flush with the face of the hub, simply counterbore the hub 0.1” deep with a Ø0.75” endmill and place a few washers on the motor shaft to offset the hub so it’s recessed with respect to the face of the wheel hub.

11. Common Prototyping Materials. Often in office hours materials like tape, hand tools, cutting supplies, cardboard, and a surface to cut cardboard are necessary. The tape is located on the rotisserie in the main lab but may run out. If this occurs grab a roll from the tape bin located on the rack located by Aaron’s lab door. The common tools and cutting supplies are located in the black TA toolbox in the appropriately labelled drawer. Above the air duct by the bathroom entrance is a stack of extra cardboard, and to prevent damage to work table or floor surfaces when cutting the cardboard use the 2’ x 4’ sections of plywood on the material rack next to the refrigerator.

12. Small Diameter Round Stock. On the left end of the main lab material rack are cardboard tubes which hold various small size aluminum, plastic, steel, and wood rods. There is also a tube containing steel threaded rods.

13. PVC Pipe. The material rack for PVC pipe is located to the right of the CNC lathe on the ceiling mounted rack. There is ladder directly beneath to access the material.

14. Motor Shaft Clamp Hubs. Students need these when prototyping shooting-style mechanisms; they are located in the black toolbox under the Abrams Table.

15. Small Wheels. Students need these when prototyping shooting-style mechanisms for ping pong balls; they are located on the rotisserie.

16. Helpful / Interesting Prototyping Examples.

17. Flywheel Testing / Mounting. If a student desires to test a flywheel mechanism, do not allow students to hold the motor by their hands for this will jeopardize the student. Grab the appropriate wheel hub and motor mounts from the TA Miscellaneous or Prototyping Hubs drawers. Construct a sturdy motor mount out of 80/20 similar to the one shown in the pictures. This design can be adjusted to what the student needs. Take note it is important to make the 80/20 that holds up the motor and motor mount so its height is adjustable to allow students to gauge the amount of pressure and clearance for a ball to pass through. If there are a lot of flywheel designs in office hours, attempt to construct about 4 mounts with various motors and make students sign up for testing each motor in designated safe areas.

Fasteners [RETURN TO T.O.C.]

1. Lab Fasteners Sizes. Become familiarize with commonly available hardware in the lab and reference this sheet with your groups as they select hardware. Any fasteners can be ordered, but it’s more work for everyone.

2. 10-24 x 1-1/4” Fasteners. 10-24 x 2-1/4” fasteners are required for the metal hub 8” drive wheels available in lab. These fasteners are in the cabinet with all the other non-standard 10-24 hardware.

3. Metric Fasteners. The metric fasteners stocked in lab are found in the lathe cabinets under the TA folder racks.

4. ¼-20 Button Head Cap Screws. There are three main lengths of button head cap screws used in the lab: 5/8”, 1/2", and 3/8”. ¼-20 x 5/8” BHCS fasteners are used to attach the OTS linear actuator mounting brackets to 80/20 extrusions, are silver in color for easy identication, and are found in the ¼” hardware drawer in the fasteners cabinet by the lathes. ¼-20 x 1/2” BHCS fasteners are the standard fasteners used with the 80/20 extrusions, are black in color, and are located in the rotisserie. ¼-20 x 3/8” BHCS fasteners are used to attach thinner parts like sheetmetal to 80/20 extrusions, are black with a painted red head for easy identification, and are also found in the rotisserie.

5. 80/20 T-Nut Tool. When assembling 80/20 with the ¼-20 BHCS and t-nuts, often the tee nuts will not immediate tighten due to the fastener not grabbing onto the threads. On the rack with the TA safety glasses there is a piece a sheetmetal bent and cut to shape. To use place bent end under the edge of the t-nut in the 80/20 channel and push down lightly this should lift the t-nut enough for the BHCS to grab and be properly tighten down.

6. Roll In T-Nut. These T-nuts are only to be used in the last week of manufacturing and testing! These roll in t-nuts are located in the Misc. Supplies drawer in the black TA toolbox, these t-nuts allow the user to use the curved of the t-nuts and roll it against the channel in the 80/20 rather than sliding from the end. This is useful due to the fact that this type of t-nuts does not require the 80/20 to be disassembled to add additional t-nuts.

Project Motors and Miscellaneous [RETURN TO T.O.C.]

1. Motor Specifications Sheets. Be familiar with the different motors available in lab so you can made helpful recommendations to the students.

2. Motor respect. As lab instructors and protectors, there are several things we must do to ensure the motors are respected:

a. Do not allow students to overload a cantilevered motor with an excessive overturning moment (it should never exceed the rated torque output of the motor); if it does, it needs to be redesigned to have a support so it’s no longer cantilevered, or to use a larger motor.

b. Require students to use ALL provided mounting holes when designing motor mounts. The only exception that comes to mind is mounting the Globe motor to an 80/20 frame member, which has never caused an issue because the Globe motor housings are manufactured from high strength 6061-T6 aluminum versus the cheaper, weaker cast metals from which all the other motor housings are made.

c. Be very cautious of the fragile motor wires and fastener threads. The wires entering a motor’s casing are easily broken if pulled on or bent tightly, and once broken they cannot be repaired. Similarly, threads in the motor housing are weak to begin with, so it is imperative to use the proper fasteners specified on the motor’s spec sheet. A simple rule of thumb to prevent fastener damage is to always ensure the mounting fasteners can be screwed together completely by hand before using a tool to apply the final tightening torque.

d. All motors except Densos should have zip tie strain reliefs to prevent wires from pulling out of their housings when accidentally pulled on.

e. Never give a motor to a group without testing it in front of the students (which includes checking each threaded hole) and making an appropriate note on their weekly progress sheet.

3. Repairing motor threads. When repairing threads it’s always best to use thread rolling / forming tap as opposed to a normal thread cutting tap, as the former pushes the remaining threads back into their proper position, as opposed to a cutting tap, which cuts away more of the damaged thread material, leaving behind an even weaker thread. I elaborate on thread repair here.

4. Buehler Motors. In lab we have two types of Buehler available for students to use. The difference between the two types is the mounting hardware: one type uses M3 fasteners while other uses standard 6-32 fasteners. To quickly distinguish between the metric and standard Buehler motors the strain relief zip ties are different colors. The red zip tie denotes the metric type and the black zip tie denotes the standard type. The majority of our supply of Buehler motors are metric, so the few standard types have been pulled from the shelf and put away in one of the grey storage bins located by the student workstations. When selecting the appropriate hardware, always be sure to check that the fasteners thread into each mounting hole by hand.

5. Entstort Hub Removal. The Entstort wheel hub requires a specialized punch to remove the aluminum wheel hub from the motor shaft due to the splines on the motor shaft. Located in the punch drawer of the red tool box is the Entstort hub punch. Prior to using the punch remove the M8 nut from the end of the motor shaft with a 13 MM deep socket. Clamp the wheel hub into a vise, load punch into the wheel hub counterbore and firmly tap the punch to separate the hub and motor shaft.

7. Motor Fasteners. At the end of the semester there are three motors in which we leave the motor fasteners to ensure that at the beginning of the following semester in order to minimize damage to motor threads. Reminder: making sure as a TA to supply your groups with the proper mounting hardware for all motors. Denso, Entstort, and Globe motors should all retain their fasteners after competition. For the Denso the M4 x 0.7 fasteners in each of the three flanges should stay and when reinstalled the addition of Delrin spacers should be added to prevent damage to the flanges. In the Globe motor face (2) M6 x 1.0 are required and in the Entstort should have three M6 x 1.0 fasteners and the motor shaft should have an M8 nut.

8. Denso Set Screws. A common occurrence when using the Denso motors is to have the set screws slip off the motor shaft. Always make sure the flat on the motor shaft is aligned with the set screw holes. To minimize this risk of the set screws slipping, clean the oil remaining on the wheel hub using Simple Green and a cotton swab located in the cleaning supplies cabinet, tighten a second set screw down against the first one, and tighten down the set screws using the long yellow handle Allen wrenches found in the bottom of drawer of the black TA tool box.

9. 80-20 T-Nuts. Did you know the regular 80-20 tee nuts are directional? The threaded protrusion should always face downwards, away from the slotted portion of the extrusion.

Control Boxes and Electrical    [RETURN TO T.O.C.]

1. Robot Testing Procedures. Be familiar with and follow the robot testing procedures.

2. Battery Connections. Be very gentle with the battery connections and make sure you always pull on the plastic connector bodies, NEVER on the wires themselves, or you will break the fragile solder joints.

3. Motor Connection Terminals. The spring loaded banana clip connection terminals on the control box are extremely robust and should present no problems when inserting or removing the mating WEGO terminals.

4. Wire Routing and Securing. Wires must always be properly routed and secured. Whenever possible, avoid routing wires in areas where there is movement (such as close to wheels and mechanisms that move). Never let wires hang in free space; always use tape (cheapest) or zip ties (looks nicer, but is much more expensive) to secure wires so they don’t move and loosen when the robot is in motion.

5. Wire Stripping. Wire strippers are used to cut and strip wires on electrical components like motors or wire extensions. If you know the wire gauge then select the labelled slot, cut through the insulation, and pull it off the end of the wire. If you don’t know the gauge of the wire, select the largest labelled slot on the strippers, and if the insulation doesn’t slide off then move to the next smaller size until it does. ALWAYS avoid cutting the copper strands; if there are cut strands the selected slot / wire gauge was too small. The base of the internal jaws contains a pair of wire cutters for trimming the wire to length or cutting off a damaged section.

6. Wire Nuts. To extend motor wires use wire nuts or WEGO connectors, after stripping the wire twist the copper strands clockwise (follow right hand rule) then twist the two wires together and screw the wire nut down on to the set of twisted wires, tug slightly on the wire nut to ensure its attached.

7. WEGO Connectors. An alternative to wire nuts are WEGO connectors. To use, open the orange prongs (this will require some force), make sure the copper strands on the extension wires are properly twisted, insert the appropriate end into the connector, and the snap the connector closed. Caution: when snapping the connector shut be careful not to pinch your fingers in the orange prongs!

8. Introduction to Soldering.

a. Here is a short video on the basics of soldering, including how to prepare the iron to start soldering. Note that most of the soldering required in lab will only be wire splices.

b. Types of Wire Joints. There are multiple ways to join wires depending on the gauge and length of wire being used. Splice the wires together and properly tin then place a piece of heat shrink around the connection. The first style (1) is called Inline Splicing and is very common. Here’s link to a nice tutorial describing the process with photos.

Bandsaws [RETURN TO T.O.C.]

1. Using Marvel Vise. This is not trivial, so please pay attention to what you are about to read. The Marvel vise has two halves: a left and a right. Always clamp both halves of the Marvel vise, as doing so mitigates the chance of circular workpieces spinning in the vise and destroying the blade. When necessary, use material drops off the rack to span the gap between the second pair of vise jaws. Make sure the vise handles are properly tightened to prevent part slippage and blade damage during cutting. If the part being clamped is less than half the width of one of the jaw halves, and adjust and use the provided machinist jack (photo 3) to act as an identical thickness spacer to prevent a bending moment from being applied to the vise jaw (photo 4). When cutting round material, the blade force must be reduced by at least 50% so as to not cause the work to rotate in the vise.

2. Adjusting Marvel Vise. The Marvel vise can be adjusted to cut wider parts by loosening the ½” bolt on the top, sliding the moveable jaw rearward, and re-torquing the bolt. When finished, please return the vise to the original position for use cutting normal lab stock. The ratchet and socket for adjustment should be stored on the machine. Be sure to clean any debris out of the ½” Allen screw before attempting to loosen.

INSERT PHOTOS SHOWING MARVEL VISE TOP BOLT BEING LOOSENED AND A LARGER PIECE OF STOCK CLAMPED IN THE VISE

3. Marvel Blade Guide. When adjusting the upper blade guide on the Marvel, NEVER loosen the tension handle / knob more than 1/4 of a turn, as doing so can cause the upper guide assembly to come off its guide track, in turn causing the blade to come off its guide.

4. Workpiece Clamping Orientation. When cutting parts in the bandsaw, it is typically advisable to orient parts so the cross-sectional cutting area remains as constant as possible throughout the cut and so the parts engage the largest number of teeth on the blade. These points are illustrated in the following image.

5. Clamping Multiple Parts. It is often helpful to clamp/cut multiple pieces of (non-circular) material in the Marvel or Roll-In bandsaws at the same time (such as 80/20 extrusion). When doing this, it’s important to clamp the parts horizontally in the bandsaw vise, NOT VERTICALLY; this ensures each part will be clamped securely, even if they aren’t all the exact same thickness.

Common Tooling [RETURN TO T.O.C.]

1. Common Drill Sizes. Familiarize yourself with commonly available drill sizes so you can help your students design accordingly.

2. Drill Index Refills. In the far left gray metal cabinet behind the mills are Huot cabinets containing refills for the drill indexes located by the mills and lathes. If you need to replace a missing or damaged drill simply looked for the appropriately labeled drawer and select the desired drill (standard or metric). Please let the lab director know if quantities run low (<12 on drills ¼” and smaller, and <6 on drills larger than ¼”).

3. Reduced Shank (Silver & Deming) Drills. In the left gray metal cabinet behind the mills are reduced shank drills that are only used in ½” collets in the mills to drill holes ranging in size from 33/64” to 1-1/2”. Never clamp these drills in drill chucks, as doing so will damage the precision shanks unless they have 3 flat ground into them 120-deg apart.

4. Aircraft Drills. Aircraft drills are extra-long drill bits. They are located in the third (from the lab door) grey metal tooling cabinet. A common use for aircraft drills in lab is placing thru holes in PVC pipe. In the photo below we started with a 1/4” drill through the first side (center) followed by a 1/4” aircraft length drill (right) which (unlike the standard jobber drill) reaches through the entire PVC pipe.

5. Extra Center Drills, Edge Finders, and Tap Guides. In the middle grey metal cabinet behind the milling machines are small white drawers labelled with extra machining tools. Some of these tools you may have only encountered the most common size located out on the milling machine table, however there are several more sizes and styles of tap guides and center drills for smaller and larger applications. Some of the smaller center drills may be helpful for smaller sized drills or taps.

6. Metric Endmills with Imperial Shanks. In the first wooden cabinet (from the lab door) on the left hand side under the drawer labelled “Odd Sizes” is an assortment of metric sized endmills with imperial (inch) sized shanks (!) that are compatible with the standard R8 collets located on the milling machines. Using normal metric endmills (with metric shanks) would require special metric collets, which would create a lot of confusion (and carnage) in the lab.

Threading [RETURN TO T.O.C.]

1. Five threads of engagement. As explained in the lecture notes on fasteners and threading, a MINIMUM of five full threads of engagement are required to achieve full fastener strength.

To calculate the minimum part thickness necessary to achieve the required five threads of engagement, multiply the thread pitch of the fastener by five. For example, if we desire to thread a workpiece for a 10-24 UNC fastener, we would require a minimum part thickness of 5 threads × (1 / 24 in/thread) = 0.208″. Or if we desire to thread a workpiece for an M6x1.0 fastener, we would require a minimum part thickness of 5 threads × (1.0 mm/thread) = 5mm ≈ 0.197″.

2. Broken tap extraction. You will see many widgets marketed as tap extractors, but they are all lies J. If you break off a tap and cannot remove it with a pair of vice grip pliers, toss the part in the trash or pay someone with an EDM to remove it. Quality taps are made of HSS, which is of equal hardness to HSS drills, therefore brittle carbide drills are required, but drilling the tap is usually an interrupted style cut, so the only thing that’s certain is that it’s going to end badly J.

3. Braddock’s Broken Rule. When you know something is broken, PLEASE ASK before trying to fix it, as trying to fix a failed fix rarely ends well, and two heads are usually more successful than one!

4. Tapping 80/20. Not coincidentally, the extruded hole thru the center of each 1” 80/20 extrusion measures Ø0.201”, which is the tap drill size for a 1/4-20 fastener. A simple way to tap the end of a piece of 80/20 is to use the jig located in the mill table tackle box. The jig attaches to the end of the extrusion using a tee nut and quick clamp handle. Attach the jig, clamp the 80/20 in a vice and use a 1/4-20 UNC tap with cutting oil to produce the threads.

5. Tapping station. The tapping station is used to quickly thread workpiece that have already been tapped drilled. Hex-shaped holders contain labeled taps ranging from #8 to 1/2”. There is a small vise with the tapping station that allows smaller parts to be securely mounted and a pin that can be placed in several holes in the base to brace the vise against rotation. The hex-shaped tap holders quickly snap in and out of the T-handle, which ensures holes are tapped normal to the table surface. There is also a rectangular block for use tapping the holes in the face of the wheel hubs (which takes about 15 seconds per hole).

Welding Shop [RETURN TO T.O.C.]

1. Welding Helmets. We have four styles of welding helmets and it’s important to understand the pros and cons of each. Let’s start with a discussion of the different lens shades available in modern welding helmets. As seen in the following chart, higher number lens shade numbers correlate to darker tinted glass. Since most laboratory MIG and TIG welding takes place between 60 and 150 amps, a #10 shade lens is ideal for most uses. When TIG welding thinner materials at lower amperage settings, a #9 shade lens would work well, and when welding thicker materials (which is rare) a #11 or #12 lens would be appropriate. These helmets should always be put away on the hooks on the north wall of the welding shop. If during use you notice any problems with the helmets (dead batteries, scratched lenses, broken headgear, etc.), please bring the helmet to the office so it can be repaired or replaced. When cleaning the plastic lenses, always use a damp clean paper towel from the restroom.

a. Jackson Passive Helmets. These are the red / maroon helmets that have a fixed, passive #10 shade lens. These work well, but the headgear is not very durable, so we keep them around as backup units in case the more complex and expensive helmets fail. These helmets cost about $60 each.

b. Miller Classic Series Variable Shade (#8-12) Auto Darkening Helmets. These are our new “go-to” helmets for normal MIG welding and welding demos. The delay (how long the lens takes to return back to the unshaded state after the welding arc ceases) should be set to slow and the shade should be set to #10. You must press the ON button before using this helmet. These helmets cost about $90 each.

c. Miller Elite Auto Darkening Helmets. These are our new go-to helmets for normal TIG welding and should only be used by TAs. The delay (how long the lens takes to return back to the unshaded state after the welding arc ceases) should be set to slow and the shade should be set to #10. You must press the ON button before using this helmet. These helmets cost about $220 each.

d. Miller Infinity Auto Darkening Helmets. These are our flagship helmets for TIG welding and should only be used by TAs. The delay (how long the lens takes to return back to the unshaded state after the welding arc ceases) should be set to slow and the shade should be set to #10. You must press the ON button before using this helmet. These helmets cost about $260 each. If you can’t weld well using this helmet, it’s time to return to machining :).

2. Welding Shop Clamps. Around the welding table and in the right-most welding shop toolbox is a collection of clamps to securely clamp parts.

a. F-Clamps / Bar Clamps. F-Clamps are simply quick acting C-clamps which are used to parts to each other or directly to the welding table.

b. Table Clamps. Table clamps come in different styles and use 5/8” holes in the welding table to clamp workpieces directly to the table for welding. If you haven’t used them, try them, because they work really well and allow you to clamp parts anywhere on top of the table, versus only around the table’s perimeter using conventional clamps. The table clamps are located in the lower drawer of the right-most toolbox.

c. Vise Grip Clamps. Vise grip style clamps exist because of their convenience of use. Used properly, they work well. Used improperly, they offer the least robust method of clamping, but work fine for general purpose work-clamping; however, they should not be used for work involving grinders, since an insecure clamping method could result in an injury.

3. Welding Shop Toolboxes. These toolboxes contain all the tools you need when working in the welding shop.

a. Pneumatic Tools. Pneumatic tools encompass all the tools in the shop which are powered through compressed air. The most commonly used pneumatic tool in the lab is the cut-off wheel which is used to create slots and square features in PVC. These tools can be found in the fourth drawer on the left hand side of the welding shop toolbox.

b. Grinders. There are angle grinders located in the bottom drawer of the welding shop tool box with replacement grinding, sanding, and cutoff wheels in the drawer above them.

c. Hacksaws. More useful tool are the hacksaws located in the Misc. Tools drawer. These can be used to cut through a variety of materials ranging from PVC to metals.

4. Metals Dumpster. All metal scrap should be disposed of into the metals dumpster located in the back right hand corner of the welding shop.

5. Heavy Duty Bench Vise. Mounted to the corner of the welding table is a large bench vise. Notice this vise has serrated jaws that increases the clamping security of parts clamped within, but also mars the surface of your workpiece. If planning on using this vise either ensure that your surface finish is not critical or add a shim (a piece of sheetmetal) between the jaw and the workpiece to prevent marring.

6. MIG Welder.

a. Power Level Settings. The power (voltage) level is used to adjust for welding different thickness materials. Setting 2 is used for steel sheetmetal, setting 3 is used for 1/8” steel (i.e. the welding demos), and setting 5 is used for ¼” steel. When tack welding pieces together, always adjust the welder to one voltage setting higher than you would for normal welding (i.e. use setting 4 when tack welding 1/8” flatbars together for the welding demos, but adjust the machine back to setting 3 before performing the actual welding).

b. Gun Nozzle. The nozzle on the end of the MIG welder has the potential the slide back exposing the internal collet from which the filler wire feeders from, when this occurs the slag from the welding process will build up between the collet and nozzle cause the filler wire to join the nozzle and collet preventing the wire spool from feeder the filler wire and prevents MIG welding from working. To prevent this from happening make sure to clean the nozzle and that the nozzle extends approximately 1/16” past the internal collet. The nozzle often shifts back when the nozzle is positioned into the corner of a workpiece with force. This nozzle can be adjusted by pulling on it, make sure that you use a pair gloves if repositioning follow a weld as the nozzle may be hot to the touch.

c. Gas Level. When the regulator reads less than 1000 PSI the tank is getting low make sure that gas has been reordered or there are additional tanks available for the MIG (Argon – CO2 Blend) and TIG (Argon) welder.

d. Wire Spool. When using the MIG welder check the status of the wire spool located under the flap on the left side of the machine, and notify Mike when the spool appears low enough to be replaced.

7. Plasma Cutter

a. Set-Up. When clamping workpieces prior to plasma cutting ensure the portion getting cut does not intersect with the table, or the plasma cutting will cut in to the welding table and damage the surface.

b. Templates. When possible, always take the extra minute to use a straight or circle cutting template with the plasma, as the cut produced will be of MUCH higher quality.

INCLUDE PHOTOS SHOWING A STRAIGHT EDGE TEMPLATE AND A CIRCLE TEMPLATE

8. Spot Welder. The spot welder does not work on aluminum workpieces!

9. Magnetic Clamps. The magnetic clamps are found along the edge of the welding table or on the side of the hydraulic press. There are various size, shape, and angle magnets to help set up parts for welding part set-up, some of the magnets have the ability to turn on and off using the switch on the side. There are also magnetic levels that can be used to align parts. Occasionally, magnets will be difficult to remove from the surface of the workpiece push the magnet over 90 degrees (forcing the magnetic surface away from the part) and pull magnet away. Warning: If using while TIG welding the arc will not like being around the magnet and jump away or not behave as normal due to the interaction between the magnet and AC current.

10. Welding Tank Safety. All tanks that are not secured to a welder need to always be secured using a chain, or strap to prevent the tanks from falling over. The tanks should always be labeled (there are magnets with labels noting when the tank is empty), and when not attached to a regulator should always have a cap. Handle empty cylinders with the same care as full cylinders.

11. Removing Welds. The 4-1/2″ angle grinder or the plasma cutter can be used to remove spot welds and bead welds from student parts which have be improperly or incorrectly welded.

12. PPE Cabinet. In the corner of the welding shop is a cabinet that contains the protective gear required for welding in the lab, this includes helmets, plasma cutting glasses, ear protection, and welding jackets. When preforming tasks in the welding shop make sure to use the appropriate safety gear and return it to the proper location after use.

13. TIG Welding. Attach documents here!

Sheetmetal Equipment [RETURN TO T.O.C.]

1. Hydraulic Shear Safety. Always wear gloves when operating the hydraulic shear because it is impossible for your hands to come into contact with the moving blade.  This does not violate our normal gloves safety rule, since there is nothing on which your gloves can catch and pull your hand into the danger zone (as there is on a bandsaw, drill press, lathe, or milling machine).

2. Deburring Tools / Techniques. As you know, sheetmetal is extremely sharp until it has been deburred. The easiest way to debur sheetmetal is to use the Noga deburring tool shown in the following video.

3. Rubber Edge Guard. This material is located in the sheetmetal table drawer labeled Sheetmetal Edge Guard. Cut to required length and slide over the edges of sharp sheetmetal parts. The edge guard can be used on both straight and curved edges.

4. Turret Punch Press. As explained on page 4 of the Sheetmetal Design Guide, the turret punch press punches various size holes (3/16″ – 1-1/4″) in sheetmetal up to 16GA in thickness. All punching should be done while the workpiece is in a flat (i.e. unbent or welded) state. When using the punch press you must activate the turret release handle and rotate the turret to load the correct punch and die set into the ram. After punching each hole it is necessary to rotate the part around the punch while sliding it downward to release it from the punch.

5. Cutting Tighter Radii, Channels, or Notches on Do-All. Cutting tighter radii, channels, or notches on the Do-All requires a technique called relief cuts, where multiple auxiliary cuts are first made perpendicular to the desired cut line to rough the part out, and then the blade is used like a high speed file to cut all the way to the target cut line. The technique shown in the following video works equally well on wood or on metal.

6. Flattening Improperly Produced Bends. To correct (i.e. flatten) an improperly produced sheetmetal bend, repeatedly clamp the part in a sheetmetal vise or lay the part on the welding table and strike it repeatedly with a hammer. Use eye and ear protection and call out “EARS!” before striking the part.

7. Rolling Sheetmetal. The lab has two sheetmetal rolling machines: a small one and a larger one. Both machines work the same way: there are two fixed rollers and a third moveable roller whose centerline distance can be adjusted with respect to the two fixed rollers. A piece of sheetmetal is insert between the rollers and rolled forward and backward to uniformly bend the material into an arc. The best way to learn how to use the roller is to just grab a piece of metal out of the sheetmetal scrap bins and roll a radius or a ring.

8. Angle Grinders. Angle grinders are helpful tools for metalworking, but they can also be very dangerous if used improperly. The following videos highlight common uses and important safety precautions that must always be followed when using angle grinders. Like most tools in the shop, the best way to become comfortable with these tools is to use them under supervision of an older TA who has been trained by our lab staff. Here is a list of points when using angle grinders:

a. Always wear the proper PPE (eye protection, face shield, welding jacket, gloves)

b. always use the factory guards whenever possible

c. unplug the grinder or remove the battery when changing wheels

d. always check that the wheel in installed properly before turning it on, and be especially cautious when installing thin cutoff wheels

e. run newly mounted wheels for a few seconds in a protected area before use to make sure the wheel isn’t defective / damaged

f. attach the auxiliary handle (if it has one) and always keep BOTH hands firmly on the grinder AT ALL TIMES

g. always turn the grinder on away from workpiece and use light pressure when contacting the workpiece

h. contact the workpiece between the 12:00 and 3:00 position on the grinding wheel

Metrology [RETURN TO T.O.C.]

1. Digital Calipers. Quality 6”, 8”, and 12” digital calipers are available in the metrology cabinet. Digital calipers are helpful when measuring larger parts or parts with metric features due to the internal electronic conversion between imperial and metric units. Additional benefits of digital calipers are that they do not suffer from parallax error and they have no components affected by chips. These particular Mitutoyo digital calipers have a resolution of 0.0005”, are IP67 rated for dust and 30 minute water immersion, and are therefore superior to analog dial calipers in every way J. Following the metrology rule of ten, these quality digital calipers checked against a calibrated standard can be trusted for tolerances within 0.005”.

2. Outside Micrometers. Quality micrometers are available in the metrology cabinet for measuring parts features up to 8” in size. Most Mitutoyo micrometers have a resolution of 0.0001”, which means when checked against a known standard they can be trusted for tolerances within 0.001”.

3. Inside Micrometers. Inside micrometers are used to measure internal features, such as diameters or slots, but only have a resolution of 0.001”. However, for improved measurement precision they can be used in conjunction with outside micrometers.

4. Thread Pitch Gages. Thread pitch gages allow identification / verification of a fastener’s thread pitch, and are available for both imperial and metric fastener threads. In conjunction with the fastener’s major diameter, the thread pitch should allow absolute identification of a fastener’s thread specification.

5. Radius Gages. Radius gages allow identification / verification of a feature’s fillet size, for both convex and concave radii.

6. Indicators. As explained on the precision metrology page, indicators have many useful purposes in a design and manufacturing environment, and we have a nice assortment of all types.

7. 1-2-3 Blocks. These are so named due to their dimensions: 1”x2”x3”. Like parallels, these blocks are precision instruments and so can be used to ensure a part or tool set-up is parallel to a particular surface datum allowing for quick fixture and tooling set ups. They also have threaded and thru holes so that allow them to be clamped to parts, fixtures, or machine tables.

Miscellaneous [RETURN TO T.O.C.]

1. Kant Twist Clamps. These clamps are located on one of the CNC carts by the VF-2, in one of the mill table drawers, and under the welding table; they are used for clamping parts together or to fixture plates. Advantages of these clamps are that they are low profile, the floating jaws always remain parallel to each other, they have built in v-blocks for clamping round work, and they are copper-plated to resist welding spatter. Notice the aluminum fixture plate clamped in the vise in the second photo; this provides a convenient method of alternative workholding.

2. Safety Glasses. Spare student and TA safety glasses are located in the second grey cabinet by the garage door. If a pair of safety glasses are scratched in the normal viewing area they should be discarded and replaced. Extra glasses can also be retrieved during high volume office hour sessions. Be respectful of the number of safety glasses consumed during the semester and always return them to the proper racks to minimize the risk of scratching due to inconsiderate handling.

3. Hand Deburring Tools. Located in the black delrin tool caddy on mill table. Listed from left to right (1) Extended Countersink Tool: useful for deburring the holes on the shoulder of the wheel hub; (2) & (3) Countersink Tools: used on holes to remove burrs along the cut edge for diameters of ½” or less; (4-7) Whirly Bird Deburring Tools: utilize a swivel blade that can deburr contours, straight edges and holes; (8-10) Scrape-Burrs: have a spade like end best used on deburring flat edges of parts; (11-12) Micro Files: a smaller version of the larger files used in the lab for smaller parts or finer material removal.

CNC Machines [RETURN TO T.O.C.]

1. TM-2 Safety Caution. The TM-2 is an open machine (compared to the VF-2 which has full enclosures to allow the use of high pressure flood coolant), and as such, does not protect the operator(s) from pinch points. Consequently, NEVER prop your hand / arm on the tool changer carousel or your foot on the base of the machine, as the risk for severe injury during the briefest distraction is too great. Always respect the machine and keep your body far enough away so you can safely operate the machine.

[PHOTOs OF PINCH POINTS]

2. CNC Distraction Warning. Everything happens A LOT faster on the CNC machines than on the manual machines, so it is HUGELY important that you never run one while distracted talking with someone. For the same reason you must be EXTREMELY careful when teaching someone else how to run one of these machines because of how easy it is to be distracted focusing more on what you’re saying to the person you’re teaching versus the actual machine.

3. TM-2 Work Offset. The TM-2 uses G57 work offset for the lab hub threading demo. About once a year this offset mysteriously vanishes for no apparent reason, so ALWAYS run the demo with caution until you are sure the part zeros are set properly (to the centerline of the rotary chuck in X and Y and the top of the chuck jaws in the Z). When these zeros need to be reset, there is a simple cylindrical part in the mill table by the TM-2 for this purpose.

[PHOTO OF PROBING CYLINDER]

4. CNC Mill Coolant Nozzles. The coolant nozzles on the CNC milling machines are usually adjusted so they are pretty close to the rotating spindle / toolholder. It’s possible to adjust them so close that they get pinched during a tool change, so always leave 4 -6 inches of clearance.

[PHOTO OF COOLANT LINES]

5. CNC Mill Spindle Cleaning Plug. We have cleaning plugs to prevent chips from entering the spindle during cleanup. If you use one of these, please do not leave it in the machine spindle when done, as the next time the machine is started, the spindle cleaning plug will get in the way of the first tool change!

[RETURN TO T.O.C.]