Setting a lathe compound slide precisely

[willthedancer]

Bolt a tooling plate to your cross slide
Clamp a straight parallel to it and dial it in with the indicator base on the lathe bed
Using gage blocks or an adjustable parallel set up a sine bar to the desired angle (sine of the angle X length of the sine bar)
Put the indicator on the tool post and dial in the compound. The sine bar must stay put for this. I just held mine here with a thumb. If it moved during slide angle adjustments, so what. I was looking for dial travel when cranking the slide.

Enjoy

 

[Randall Marx]

I like it! Too bad I don't have a sine bar or anywhere to bolt the tooling bar to my crosslide. I like the thought process, though.

 

[willthedancer]

You can set up the plate on top of the lathe carriage too, maybe on 1-2-3 blocks on top of the cross slide's flat bearing areas. Clamping becomes more challenging, but it can be done.

 

[heli_av8tor]

Check out Joe's YouTube video:

 

[chips&more]

I just watched that video, interesting, but it has a mountain of uncertainties. Saying it is the most accurate is a real stretch.

 

[willthedancer]

It's another way, but I am not certain of my screws in my crossslide, compound, or the straightness/wear/alignment of my tailstock quill. In my post, the only uncertainties are headstock alignment, condition of the spindle bearings, and condition of the compound slide. All of those are in play in both cases. The only improvement I can come up with to what I did was to use a test bar in the spindle, but that is another evolution all on it's own, and my tired old lathe would not merit it.