Lab 2: Machining Innovation Fellows Program Bootcamp Prof. Steven S. Saliterman The following exercises are meant to familiarize you with the capabilities of the Earl Bakken Medical Devices Center (MDC). You should only participate in exercises that you are comfortable doing. Skip over anything that you feel uncomfortable with. Ask for direct supervision while performing something new until you feel you can proceed safely alone. Supervisors Steven and John are in room G217-05 in the MDC. Exercise 2-1: Safety Training You must complete the MDC online safety course before using the facilities. When you use the Anderson Innovation Labs or CSE Student Machine Shop, then you must complete their safety, training and login requirements. Exercise 2-2: Familiarization with Materials Objective: To introduce you to materials that you will be using in the shop for machining practice. Stock material may be in your lab box or stored in the CSE Student Machine Shop. A. Aluminum, 2 x ¼ flat plate, 6061. 2/18/2018
Page 2 Exercise 2.3: Medical Devices Center (MDC) Small Group Instruction Objective: Instruction in various hand and machine tools found in the MDC machine shop. The MDC supervisors will be instructing. Hand Tools Drill Press & Vertical Bandsaw Belt Sander Height Gage on Granite Plate and Dykem Blue Notes: Instructor, please initial student s completion of this instruction:
Page 3 Exercise 2.4: Sawing, Drilling, & Tapping Holes Objective: Cutting a piece of aluminum flat to size, locating holes, drilling, and making threads with a tap. Knowing how to manually layout your workpiece is essential because digital readouts (DROs) are not on every mill and lathe, and many drilling operations are done on a drill press. (Dial indicators and handle gages are also useful when no DRO is present on a mill or lathe.) You may complete this exercise in the MDC. Equipment and hand tools needed for this exercise: Band saw Belt sander Drill press Machinist square Dykem blue and remover Height gage and granite surface Center punch (spring loaded) Center/spotting drill #29 drill bit 8-32 tap and tap wrench. Countersink (82 degree chamfer) bit for drill press. The following pictures illustrate each step necessary to complete the part. While only one hole is completed (drilled and tapped) here, you will complete all four holes in your workpiece. A complete list of steps in written form follows the pictures. 6061 aluminum stock - 2 x 12 ¼ Toolbox for this exercise. Similar tools can be found elsewhere in the MDC Mechanical lab.
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Page 5 Marking the 2 cutting line. Lubricating the saw blade (perform on both sides). You will need to temporarily lift and lock the blade guide. Be sure to lower the blade guide to just above your workpiece. Checking clearance of the workpiece under the blade guide. Notice the rough cut and lack of squareness after cutting with the band saw. Use a disk sander to square the rough cut. Slowly move the workpiece back and forth but only in the front half of the disc.
Page 6 Check squareness with a machinist square. Applying Dykem Blue. Making the 1.625 marks. Making the.375 marks. Center punching the crosshairs. Center drilling after center punching. Only a tiny starter hole is necessary. This keeps the drill bit later from wandering.
Page 7 The crank on the right lifts and lowers the drill table. The handle on the left locks it in place. Workpiece secured in a vice for drilling. It is not necessary to clamp the vise to the table. Instead, firmly grasp the vise with your hand while you drill. Peck drill in and out. Drilling with the #29 drill bit. Examples of center punched, center drilled, and drilled holes (x2) (cc). 8-32 tap and tap wrench. Place into the drilled hole and with a little downward pressure turn clockwise. Occasionally make a ¼ turn ccw to break chips. The 8-32 tap should be tapered and pointed at the bottom for tapping holes that go through the workpiece. Advance the tap well through the hole, then backout.
Page 8 Manually turn the 8-32 tap with the wrench. Keep advancing until most of the tap threads have gone into the hole. Chamfer bit Chamfer drilling. Dykem Blue cleaner Completed chamfer and tap. Tapped hole with an 8-32-3/8 flathead screw in place.
Page 9 Summary of Steps: A. Begin with a section of aluminum flat plate, 2 wide and ¼ thick. Measure a length of 2 and cut with the band saw (leave a little margin for sanding the edge smooth). B. Using a disc or belt sander, lightly sand the sawed edges so that they are square with the factory finished edges. The part should measure about 2 x 2 when you are done. (If precision squaring and sizing were required, you would complete this operation using a mill instead.) C. Layout the pattern below on the workpiece using Dykem blue and a vertical height gage (use a common datum as shown in the drawing below). D. Center punch the holes first, then make precise starter holes with the center/spotting drill on the drill press, and finally drill through the workpiece (x4) with a #29 drill bit (based on an 8-32 tap). When drilling, hold your workpiece in a vise and be sure there is clearance below for the drill bit. Use a drop of lubricant. E. Next obtain an 8-32 tap and tap wrench, and proceed to manually tap the holes. Holding the wrench and tap perpendicular to the workpiece, apply downward pressure and slowly turn the wrench clockwise so that it will cut the threads. Once cutting, after ~every one turn in, make a ¼ turn counterclockwise out to break chips that form. A drop of lubricant will help. F. Using a countersink, add a large chamfer on top for the screws, and tiny chamfer on the bottom to deburr each hole (removes sharp edges). G. Test the holes with an 8-32-3/8 Phillips flat head machine screw (leave one in place). H. Remove the Dykem blue with the Dykem cleaner (wear gloves). Return the cleaner to the designated inflammables storage cabinet. Instructor, please initial student s completion of this part: End of Machining Exercises