Lathe Compound Slide (cont)

These mini lathes have a slight problem. While I was installing my 20 TPI conversion and new compound, I decided to fix it once and for all.  Lets look at that problem, and how I solved it.

On the compound slide, the moving dial can (uh...will) bind against the stationary dial (see the pointer). What this means is that you can't always trust the reading. I don't run a DRO on the lathe, I never have. I have this thing about DRO's on lathes, I don't know why. Anyway, I rely on the dials.

The cross feed screw does not bind up. Hmmm...but why? As it turns out the cross slide screw is captured by the thread housing (for lack of a better word). The screw has a shoulder, and that shoulder is used to limit the movement of the screw. The compound slide lacks this feature. So, no matter what, the screw will bind against the dial as you feed in.

So, I screwed around in Fusion360 a bit and came up with this. It's a half moon that will be screwed to the back of the stationary dial and capture the shoulder of the compound screw. I'm new to 3D modeling, so every "problem" I have is an opportunity to draw it up and fiddle in the digital realm. It helps me learn. The basics of this part would be a few minutes on paper...but it took me a little bit to model. As I gain experience, I'll be able to speed up the digital side.

Simple lathe operations. Face, drill, bore.

I then cut the round in half, to make two. I don't need two, but figured I'd make a second one instead of wasting the material.

Test fit on the screw. You can see how the major ID of the half moon captures the shoulder of the screw. This limits the ability of the screw to tighten against the stationary dial.

Finished parts. The matte finish comes from a soak in acid. It's just something I like to do.

Installed. I set the half moon against the stationary dial with the screw installed and used a transfer punch. I then drilled and tapped for M4 socket heat cap screws.

This worked out pretty well. One thing that slowed me down is that the shoulder on the screw was not concentric to the screw. It caused some rubbing and binding. I had to turn down the diameter of the shoulder just a little to finish the fit. Also, it will limit the movement of the compound slightly. I don't think it's a problem since I rarely find a need to run my compound slide all the way in to the limit.