The deviation varies a lot . From 0.5mm to a few mm . the screw is 10mm pitch but the operator has never seen a deviation of exactly 10mm . So the home switch is not tripped a thread early .
I'll try to run some more experiments this week .
Is there a possibility linuxcnc isn't saving properly ?
Most anything is possible - but that is very unlikely.
It sounds like mechanical to me - though a few mm is an awful lot.
Is this new behaivour or it's always been like that?
What type of encoders are you using?
It's been like that for quite some time . And I've had the chance to check everything mechanical . I've had my doubts about encoders but everything checks out fine .
The machine is a mori seiki with red hat fanuc drives . The original drives were replaced for a set of drives manufactured locally, that accept the weird fanuc signal . Output on these is not that difficult to use A B and C are standart . Only the commutation signals are a bit odd and are not differential .
The machine holds tolerances very well . I've personally checked motor couplings and they are solid . Bearings on the screw are good .
Cheers
P.S. I'm not entirely sure but I believe the problem gets worse if the computer is turned off incorrectly .
I ran a couple of experiments .
If power is turned off while linuxcnc is running it wipes the .var file clean . Nothing in it . And as lcnc is started it writes a file with all parameters = 0 .
Is this normal ?
machine runs 2.7.15 (updated today) on debian 9 with a mesa ethernet board .
P.S. What is the relationship between the .var and .var.bak files ? When is the bak file saved ?
Any details around the backup would be helpful .
An experiment I have never thought to do is to look at the timestamps of the .var file, to see if it is written during machine up-time (for example after a touch-off) or only at shut down.
I wonder if the "wrong" offsets might match the right ones from a previous day, and the whole problem is with the .var file not being written for whatever reason?
