USING THE LATHE TO MAKE THE TENSILE TESTING SAMPLE

Preparing the Sample

Step 1. Select 1 / 4” diameter aluminum and brass round stock, clamp in a bench vise and cut each piece three inches long using a hand hacksaw.

Step 2. Square up and chamfer both ends of each piece on the one inch belt sander or bench grinder.

Step 3. Place each piece in a metal lathe 3 jawed or collet chuck. Extend the stock out from the chuck one inch. Clamp the work tightly in the chuck.

Step 4. Set up tool as shown and tighten tool post. Turn cross feed hand crank into work taking light cuts across the end. Face both ends of the stock smooth and square.

Step 5. Place a 1 / 4 – 20 NC die in a lathe die holder. Tighten with an allen wrench and clamp it in the lathe tailstock chuck.

Step 6. Slide the tailstock with the clamped chuck and die up to the end of the work.

Step 7. Adjust the lathe spindle speed to its slowest RPM’s. With lathe turned off engage back gears.

Step 8. Turn the lathe switch on. Push the tailstock and threading die into the rotating work and begin threading. Make the thread 1 / 2 to 3 / 4 in. long then turn off lathe switch.

Step 9. Turn the lathe switch in the reverse direction to unthread the die from the work.

Step 10. Slide the tailstock to the right clearing the work.

Step 11. Turn the stock around in the chuck, clamp and thread the other end following the previous steps.

Step 13. When the final thread is complete slide the tail- stock to the right and remove the threading die and holder from the tailstock chuck.

Step 14. Select a small center drill no. 2 and clamp it in the chuck.

Refer to the Machinist’s Handbook and set the RPMs to the appropriate speed for the material

Step 15. Slide the center drill up to the end of the work and clamp the tailstock to the lathe bed with the tailstock wrench.

Step 16. Turn on the lathe with the work turning toward the operator and slowly advance the center drill into the end of the work by turning the tailstock hand wheel.

Step 17. Slowly drill until the center drill is 3 / 4 of the way up its 60 degree taper. Turn off the lathe.

Step 18. Unclamp the tailstock from the lathe bed and slide it to the right clearing the work.

Step 20. Replace the center drill and tailstock chuck with a tailstock dead center. Be sure the dead center’s morse taper is seated and centered in the tailstock spindle.

Step 21. Unclamp work from the chuck and slide it out 2-3 /8”. Reclamp the work in the chuck. Measure and mark the one inch center section of test sample as shown below.

Step 22. Slide the dead center and tailstock to the center drilled end of the work. Tighten the tailstock to the lathe bed with the tailstock wrench.

Step 23. Turn the tailstock hand wheel to advance the dead center into the center drilled hole so that it is a snug fit and lock the tail stock spindle with the spindle lock lever.

Step 24. Place a small round nose tool bit into a lathe tool bit holder and tighten it down.

Steps 25 and 26. Slide the lathe tool post into the T-slot on the compound rest. Slide the tool holder and tool back into the tool post as shown.

Step 27. Line up the cutting edge of the tool bit square and at the horizontal center line of the work.

Step 28. Now tighten down the tool post with the tool post wrench. Be sure the tool holder and tool post are very tightly clamped to the compound rest T slot.

Step 29. Turn on the lathe. Advance the tool bit slowly into the work .020. Turn the apron hand wheel counter clockwise to move the tool bit to the left for a distance of one inch.

Step 30. Reduce the diameter of the one inch center section you previously marked down to .110 by advancing the tool bit into the work with .020 cuts.

Step 31. Turn the lathe off and measure the diameter frequently. As the diameter gets close to the finished size take smaller cuts with the last few finish cuts as little as .002.

Your two finished samples should look like the sample below.

Thoroughly clean the lathe and return all tools to their proper place