Ok so my machine has been working nice and today i have been threading

I am using the G76 for threading and the threads seem to be very good.

In between parts i re referenced the machine and this is where the problem lies.

I hit my home switch as normal but it behaved differently when it backed off the switch, i can only describe it as though the motors were re-tuned instead of the normal sound "Eee" i got lazy sound like "Whooa" 

I quit Mach the restarted Mach and it was back to normal

And no this isn't a wind up thread

Phil

Don't have an answer for you. What version are you using? Do you have backlash compensation eneblaled?

RICH

Can you do it again?
Hood

Hood, Rich

No Backlash, and using Smooth stepper.

The machine seems to be working well, i only did a re reference to be on the safe side.

To test I just fired the machine up homed as normal it was normal.

Run the code with G76

Homed it again and now lazy back off.

Closed Mach, then restarted and homing back to normal.

I am using version 029 the lockdown.

I know if i use that home with the lazy backoff the machine will not be where it's supposed to be.

I found that in testing, the machine will home to within .0002" repeatedly but if i alter the motor tuning or the homing percentages

it will still home repeatedly but just in a different position. I only have one version of the M1076 Macro and it is dated Sept 25 2008

Maybe you could test yourself sometime you do a thread maybe you Rich as you seem to be doing a lot of threading at the moment. 

Phil

I can't test I am afraid as I do the homing externally from Mach.
Hood

I can't test I am afraid as I do the homing externally from Mach.
Hood

Hood are you trying to tell me something.

I have just thought of something when the machine is threading the movements seem quite violent more so than just doing a G0 move

I have the motors tuned to 2000mm Velocity and 200mm acceleration which gives a G amount of .02395 etc

Phil

Only thing I am telling you is Mach does not do the homing on my lathe
Reason is I can do index homing with my servo drives and that in itself is deadly accurate but I also have it set so it  gates the Index to  the A and B channels so its even more accurate

Hood

I don't even have limit switches installed on the lathe yet, and, don't use homing without switches.
SO can't try or help on that matter.
I have run the lathe at many different velocities  and the G0 moves all seemed apropriate after  each thread cycle.
Haven't even tried ver 029.
RICH

BTW: I don't use the G76 as i like to know what pass screwed something up in the thread testing.

Hood,

Do you use G32 or G76

I think i may need to work on my post processor as i get what i would call a cnc thread in that the last thread is swept out if i use G76.

But if i use use G32 the thread stops at the designated Z position and is then cleared to the clearance X position and appears to be done by manual means in that the tool cuts full circle at the end of the thread.

Hood or Rich could you post some sample code ? so i can see what ia am aiming for.

Phil

Yes G76,
 Heres the threading snippet from the thread I did yesterday.
M4S1200
T303
G0X20.835Z7.758
G76 X13.39 Z-18.006 Q1 P2.0 H0.136 I29.0 R15.822 K6.228
G0X31.08Z7.758


Hood