Couple Of Lathe Questions

[churchjw]

I have several of questions about the compound slide on my lathe.
The first is a general question, not dependent on lathe type. My compound is graduated in .001". Does anyone know what angle to set the compound so that each .001" moves the tool .0001" in the direction of the cross slide? I know I saw this written up some where but now I can't find it.

The second 2 questions deals mainly with the wholesale tool lathe WT 13" x 40" Gap Bed Geared Head Lathe or any lathe with the same layout on the compound.
When I first got my lathe I used a dial indicator to check to see if the cross slide dial was accurate. It was not. After some reading and checking around I found it was because they used a metric screw that was close to the right pitch but not exact. So I switched the screw out for a standard 10tip and now it reads spot on. Has anyone done this to the compound rest screw? If so what was your procedure?

Second question has anyone mounted a digital caliper to their compound as a cheap DRO? If so how and what position.

Thanks,
Jeff

 

[schor]

mrpete222 did a video where he explained the angles. Can't seem to find it now.

Here's my cheap dro for my atlas for the crosslide, not sure I could do it for the compound on my lathe.

 

[MozamPete]

5.74 degrees to the axis of the lathe should give you a 10:1 ratio (sin 5.74 = 1/10)

btw 23.2 degrees to the axis give you a ratio where 0.01" on the compound give you 0.1mm in-feed towards the work. Handy when working with metric measurements on an imperial lathe.

 

[Steve M]

By my math, an angle of 84.26 degrees on the compound measured from the perpendicular to the the working surface gives 0.0001 advance of the cutter for an 0.001 advance of the compound. 60 degrees off the centerline of the cross slide yields .0005, probably a more reasonable dimension to shoot for. I've used a magnetic stand for my dial indicator as a manual DRO. Usually have to set it up on the other side of the spindle and position it against the compound. Seems to work fine for me.

Steve