I¡¯ve installed a new 16in bed on my 7x12 LMS 4200 mini-lathe and added a new tailstock with DRO. I sent for a 350mm MT3 Test Bar from India rated 0.0001¡± runout (not defined) and mounted it between the spindle and a live center in my fully retracted tailstock quill. After a low speed spin as I tightened the tailstock up. I mounted an indicator on top of the compound slide and ran it ~8in from the tailstock end as close as I could get my carriage to the spindle.
With the indicator vertical on the top surface of the bar, maximum change was 0.004¡±, horizontal on the front surface the maximum was 0.0025¡±.
Given the tolerance stacking across all the stationary/moving parts, that comes to a maximum deviation of 0.0005¡±/inch Z-axis. For such a mini-lathe, is that in the expected/acceptable range for hobbyist work?
BRET
