lathe a xais questions

[eloid]

Im planing on make a axais lathe

how does one calibrate it ( a axis), x,y,z you use digital guage block....
what are the steps required to accurately set up the rotation pecicsion?

[Pandinus]

I made a small reference mark on a large diameter and did one rotation... looked all right, did 10 more, still looked good... then went around 100 times and I still couldn't see any deviation... was good enough for me.

[eloid]

The question i had is there menu or calibration seting in mach just for A axis.. like there is for xyz its been some time since i looked at those screens...where you set the feed rate and measure distance? but in this case its rotation and speed/ time
that may improtant?

[Pandinus]

I actually learnt something last night worth passing on in this subject... Still dont know it all yet or even enough... lol
Anyways, in general config there is a section on a-b-c axis for angular or "Unchecked For Linear" It turns out that this when checked tells Mach not to convert that axis from metric to imperial or the other way around. So If you are using that axis set for rotation, a G20/G21 don't affect it... if unchecked A G20/G21 WILL affect the axis...
As far as set up, its the same as x-y-z you enable the axis in ports and pins then set steps and acceleration/velocity in motor tuning... and really I suppose you could set it to anything that works for you, but then be careful running other peoples code!
What I mean is if you want to set it for Degrees or Radians you can, or calculate your final OD linear speed, you can, like if you are engraving a 2" cylinder you could calculate for the steps per inch on your surface and use Linear to convert metric... But for anything other than 2" it would be wrong.
Most "A" axis are gear driven rotational, so fine tuning it should be unnecessary I.E. 200 steps per revolution and a 10 times gear reduction is going to be 2000 steps per rev of the axis period, if you are using an non-toothed belt you will no doubt get slippage and can't do much to compensate for it, but I have contemplated a system for putting a barrel on my plasma table with a belt "hangar" of sorts to do cuts on it, but that would translate to a linear value anyways...