Messages

21

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 02:24:49 PM »

OK I have a .001'' dial indicator, so each graduation is .001''

Moved into the indicator and set it to zero then did these moves away. I did .100'' moves so the hand on the indicator had to do a complete 360 movement.

x+.2 should be .100'', indcator reads .089''

x+.4 shoudl be .200'', indicator reads .1985''

x+.6 should be .300'', indicatoe reads .2985''

x+.8 shoudl be .400'', indicator reads .3988''

x+1. should be .500'', indicator reads .4991''

x@1.2 shoudl be .600'', indicator reads .5987''

Please bear in mind that I don't have any graduations within the .001'' marks so I was estimating the fourth digit.

Did X0 and the dial indicator was approx .0001'' short. Just a fraction under a complete return to zero by the indicator I have.

22

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 01:42:59 PM »

Will do Hood

23

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 12:28:09 PM »

I'm taking .005'' cuts, thats .1269mm each cut so I don't understand how there can be too much pressure on the tool. I was taking .010'' cuts or .2539mm before, even then I cant see how there could be too much. I can just about push .001'' on the tool post against the indicator. Actually managed to rock the 750Kg lathe a little doing that.
If I command an X move of 1'' (.500'' as in Diameter mode), then the dial indicator runs out by .002'' under, ie it shows .498'' total movement.
Lets say that the .005'' (.1269mm) cut is causing the tool post to move by .004'', that would give a total of .494'', but I get .485'', another .009'' from somewhere.

.500'' diameter cuts to .485'', or .015'' out.

Is it possible that the software is causing this? As the tool is moved in and out through multiple passes the error gets larger and larger?

Why can it cut .100'' accurately with the same tool pressure, working down to .500''.
With .015'' error I should have seen .003'' on each of those passes. 

24

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 11:51:20 AM »

Just checked with the indicator. Against the Aloris tool post I can just about push .001'', thats measured off the tool holder, the tool is rock solid in the holder.

Cant push a thing on the slide against the ball screws. Everything else is rock solid.

25

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 10:21:46 AM »

Hi Hood
Do you have any idea why its so far out when cut in a single pass?

With shallow cuts too.

26

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 10:16:02 AM »

Just did it in one pass and got .485'' instead of .500''

So why is it .015'' out when cut in a single pass, I used the shallower cuts too.

27

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 09:45:34 AM »

OK so I measured the OD of the stock and it came out at .995''

First pass was set to cut .900'', that measured .899'' to .900''

Second pass set to cut .800'', that measured .800'' to .8005''

Third pass set to cut .700'', that measured .698'' to .701''

Fourth pass set to cut .600'', that measured .600'' to .6005''

Fifth pass set to cut .500'', that measured .4995'' to .500''

All cuts based on the original diameter of .995'', so later cuts had lots of fresh air passes.

So it seems to be working. But I have not changed any settings.

I took shallower cuts of .005'' at a time, before I had been taking .010'' and gone from .995'' to .500'' in one cycle. Could that have been too much?

28

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 08:51:02 AM »

Ok

I jogged onto the indicator so that it started moving a few places, then I stopped and zero'd the DRO. Then I jogged in reverse and stopped the minute the dial moved, in this case one tap with .001'' set and the DRO reads .0016''. So even less.

I am in DIA mode so thats .0008''.

I have some '' I can turn to say .900'' and then .800''

Cheers

29

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 08:13:53 AM »

Ok, did as you said.

Put a .001'' dial indicator on X and set it to zero. Set Jog Cycle to .0010'', first tap nothing, second tap dial indicator moved. DRO reads +0.0024'' so double that .0048''.

Does that sound right Hood?

30

General Mach Discussion / Re: Motor Tuning

« on: February 28, 2013, 06:15:20 AM »

Much better thanks Hood but still a bit out.

I programmed .4989'' and got .4850'', so .0139'' (.353mm)  out on the diameter.

Is there anything I can do to get this more accurate. Could it be backlash that causes the inaccuracy?

Z seems to hold about .001''

Thanks very much for your time on this btw.