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2024-06-20Project: Drawbar
Once I had a thread protector, it was time to make a drawbar for the MT2 collet I have. I plan to use MT2 collets primarily to hold milling cutters for horizontal milling applications.
I've got a ton of 1/2 all-thread left over from a project (unrelated to the lathe), so I decided to go ahead and make one out of that. That gives me one end (back end) that's already threaded for tightening. The collet I have has a 3/8-16 female thread on the back, and a counterbore.
I turned the all-thread down to 3/8, and then single-point threaded it 3/8-16. I made it plenty long so that I could turn a thick 3/4 washer/bushing out of aluminum. This serves 2 purposes: 1) it provides a solid interface between the back of the collet and the all-thread and 2) it helps loosely align the all-thread in the center of the spindle bore which makes it easier to start threading.
The thick nut. All of these cuts look really rough up close. I was moving quickly, and doing a lot of the work by hand without the powered feeds, but in person the finish seems perfectly adequate for their function.
On the back end (sticking out above the change gears) I made a simple aluminum bushing with a loose 1/2 center bore. I can then use a standard nut on the all-thread to tighten the whole assembly.
This holds the collet nice and securely; here's the uninteresting view from the front, where you can also see the thread protector in action.
And here's the assembled unit, but outside the spindle. This photo has the collet unscrewed a bit to show the 3/8-16 threads in there.