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Axis compensation

PostPosted: Tue Jan 09, 2018 1:15 am
by Davemorl

I was wondering if anyone knew if you can compensate for an out of square axis with UCCNC like you can do with mach3? I can't see anywhere in the manual how to do it so I'm guessing not unless I'm missing something?


Re: Axis compensation

PostPosted: Tue Jan 09, 2018 2:34 am
by cncdrive
Yes, you can compensate an out of square axis.
Squaring automatically happens when homing the axis if:

- There is a master and slave axis defined.
- The master and the slave have different home input pins defined.

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 2:37 am
by Vmax549
I think he may be referring to teh use of FORMULAS to correct axis motion.

Just a thought, (;-) TP

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 2:45 am
by cncdrive
He wrote "compensate for an out of square axis", so I think he did not talk about axis mapping, but axis squaring of an out of square gantry.
Axis mapping is to compensate pitch errors and so it is nothing to do with axis being out of square, so I don't think it is what he asked about...

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 10:31 am
by Davemorl
Apologies for any confusion in my original post.

Yeah it's the use of formulas that I was looking for, the out of squareness is only very small like 0.05mm on the x axis over 4 inches of travel on the y axis. To adjust this mechanically would be almost impossible on my machine so was wondering if I could correct this through UCCNC like mach.

My machine isn't a gantry type. I've attached a picture for your interest. It's still a work in progress.

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 11:54 am
by ger21
Formulas in Mach3 can be buggy, and if using it as you describe, there are certain conditions that can cause a loss of position on the compensated axis.

It's all these added "Features" in Mach3 that contributed to it's lack of stability, and overall buggIness.

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 2:57 pm
by Davemorl
Hi Gerry, so is that you basically saying that it doesn't have this fuction? Is there any plan to introduce it as I know UCCNC is leaps and bounds over mach3 in all other aspects.

I will have servos on my new machine so loss of position shouldn't be a problem as such as it can't loose steps.

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 3:34 pm
by ger21
No, UCCNC doesn't have Formulas for axis correction. And I personally don't think that it should. There are many other standard features that should be added before a feature that almost no one would use. (Sorry)

The issue I'm talking about would cause a servo fault, as Mach3 tries to jump from one position to the compensated position instantly, with no acceleration.

I'm surprised you have'nt seen it, as it was pretty obvious when I played with Formulas a while back. I don't remember the exact conditions where the formula isn't applied, though.

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 4:41 pm
by cncdrive
Yes, that's correct. The UCCNC does not have formulas to correct the screw pitch differences.
However that part of Mach3 is really buggy, so I would not use it with Mach3 either.
It's fine that servos can't loose position, but you will still see the results on the workpiece of the bugs how mach3 handling the correction,
because however your axes will not loose steps, but jumping accelerations will cause the machine to shake...

So, I think that you should look for something else than UCCNC or Mach3 if you successfully want to do pitch correction on the machine.
I don't know though if there is any cheaply available softwares out there which correctly handing this?!

Re: Axis compensation

PostPosted: Tue Jan 09, 2018 6:41 pm
by Davemorl
Ok, thanks for your replies.

Gerry I haven't actually used it on mach3 but what I've read it is very buggy like you say. I was just hoping deep down that UCCNC had this function minus the bugs. I am just looking for a quick fix till I can get this machine up and running and re machine something and get it square as all the holes have been manually drilled by a drill press. Ones it's working I'll try and resolve it. To be honest I'm just splitting hairs but you know what it's like if you can improve something then it just niggles at you if you know it isn't right :lol: :lol:

Thanks again for your help.