Backlash speed

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20 Mar 2016 12:26 #71942 by GaryLa
Replied by GaryLa on topic Backlash speed
Ok, thanks. I'll look into that file.

I have changed some parameters in both Axis and the Tormach INI, but they were display-related or minimal config changes. Through trial-and-error I found changeable parameters and unchangeable ones.

The backlash issue irritated me so I called them. They stated "we don't know anything about those parameters, so we don't support it." I then stated that I knew about them and how to use them so why would they disable my access to them!

There's really no valid excuse. If they were solely concerned about tech support issues, they could've simply moved their INI file checking code to a separate program which they'd ask you to run when you called tech support. This program would then list the differences between a Tormach install and a user-changed install. Alas, I'm finding that Tormach's technical expertise is pretty dismal. BUT - I don't mind that, I mind the fact I'm limited by their lack of knowledge of LinuxCNC.

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20 Mar 2016 12:50 #71943 by cncbasher
Replied by cncbasher on topic Backlash speed
you'll get far better advice here , then you ever will at tormach .
especialy if your running a non tormach machine,

you should find that whatever config is available for linuxcnc version before lets say 2.6.4, will work .
however some components have been removed , abiet easily re-added , so long as you can obtain them compiled for the
i quoted , however some newer additions say from 2.7 and the latest , will be missing .
i can help if your stuck etc , as i'm doing a lot with Pathpilot commercially.

most errors are trivial to sort , but not sometimes easy to know where

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20 Mar 2016 13:38 #71945 by GaryLa
Replied by GaryLa on topic Backlash speed
Thank you, good to know!

I'm helping out and doing some teaching at a local makerspace. Someone graciously donated some equipment including a PCNC770.

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20 Mar 2016 13:47 #71946 by cncbasher
Replied by cncbasher on topic Backlash speed
if your getting backlash , i'd look at the condition of the ballscrews , sounds like they may need new balls ,
if it's that worn out , look at the oiler etc

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21 Mar 2016 16:46 #71992 by GaryLa
Replied by GaryLa on topic Backlash speed
The Z axis was measuring 0.0027 in backlash, while X and Y were about what I'd expect from typical ballscrews: around 0.0006.

I really wanted to add the backlash parameter for the sake of the Z.

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21 Mar 2016 16:59 #71993 by cncbasher
Replied by cncbasher on topic Backlash speed
i cant expect the backlash not to work , have you tried putting the entry in the ini file .
BACKLASH = 0.002 for example .

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25 Mar 2016 12:01 - 25 Mar 2016 12:03 #72129 by GaryLa
Replied by GaryLa on topic Backlash speed
Because Pathpilot doesn't allow some parameter changes I decided to to not use it at all. I was specifically told by Tormach tech support they did not support backlash in LinuxCNC. (Whatever that means...)

I wasn't sure if not increasing the acceleration would give me any benefits. I didn't research it. But Pathpilot did boot with just BACKLASH in the INI file. So if your experience is that it would do some good without adding to the acceleration, I'll put it back in.

Thanks for your attention on this. I had bigger fish to fry and forgot about it until I saw this thread.
Last edit: 25 Mar 2016 12:03 by GaryLa. Reason: typo

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25 Mar 2016 16:39 #72143 by cncbasher
Replied by cncbasher on topic Backlash speed
it's a simple matter if backlash works , then it works , got nothing to do with Tormach , it's a function of Linuxcnc
unless your using a tormach machine , they wont be interested in anycase .
if you really need it and you find it's missing then I can add it . that's the joys of open source and Linuxcnc
Pathpilot is nothing more than a GUI front end to Linuxcnc , with a caveat that it's cut down in certain areas to suit tormachs requirements , it's approximately version 2.6.3 under Ubuntu 10_04 .

hope that helps

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26 Mar 2016 13:02 #72180 by GaryLa
Replied by GaryLa on topic Backlash speed
I do understand what you're saying. Over the years I've written a fair amount of OS code under Linux (usually kernel modules to support hardware).

But I wasn't sure how well it would function without allowing it to move more quickly to take up the backlash. I'll admit I didn't give it a lot of thought.

My experience with it was:
1) I changed the INI file to include BACKLASH and the proper velocity changes
2) Pathpilot booted and complained
3) I called tech support and they stated, "we don't support it".
4) I commented out my changes

I'm glad you pointed out I don't have to have the velocity changes as LinuxCNC will still account for it -- I wasn't sure how it would behave so I left it out. I hoped to get back to it "one day". Looks like that day has come...

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