Backlash compensation > does not compensate enough

Discussions and help on this commercial controller.

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Re: Backlash compensation > does not compensate enough

Postby Techgraphix » Sat Dec 12, 2015 6:15 pm

bloq wrote:P.S: When i use x_swing very very slowly (100 and with ppi set to 600) the results are very good. Does this point to backlash problems or is this something else.

Beltstretch or torsion-distortion.. When you reduce the acceleration instead of the engraving speed, you would probably get the same effect?
What is your "normal"engraving-speed? I think a 200 to 400mm/s (depending on the material) gives you the best results..

Kees
Techgraphix
 
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Re: Backlash compensation > does not compensate enough

Postby Techgraphix » Sat Dec 12, 2015 9:43 pm

bloq wrote:I guess you do not have a bom or something like that? Or even plans? If my (future) machine could do that i would be more
than happy ;-). When i am in the netherlands for the next time - would you mind if i take a look at the machine?

I do have all kinds of drawings made in MK-Cad6 and CAM-files to machine the parts like the mirrormount, bearingblocks etc in ArtCam.
You're welcome to visit me in Appelscha (south east of Friesland, near the second largest woods of the Netherlands..)
Kees
Techgraphix
 
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Re: Backlash compensation > does not compensate enough

Postby bloq » Mon Dec 14, 2015 11:52 am

ok i will try the snake test. This is meant to be made as a cut not as engraving?

Regarding the speed: with one direction lasering i can go up to 400 with very good results. With the bi directional lasering the only time this was possible with
settings that low that it would be faster to stay with one direction but at higher speeds. I already reduced the acceleration to 5.000. Do you think i need to get
even lower?

Thanks

Andre

P.S: Would you share your drawings or are they top secret? Next time i visit the netherlands i will make a stop at your shop : )
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Re: Backlash compensation > does not compensate enough

Postby bloq » Mon Dec 14, 2015 2:58 pm

Hey,

i made a test with max_acceleration down to 2000. As you said this also helps with the offset issues when making a x_swing engraving. I did not yet do the snake test. Does the fact that the reduction of the acceleration works speak for a backlash issue?

thanks

tm
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Re: Backlash compensation > does not compensate enough

Postby Techgraphix » Mon Dec 14, 2015 4:36 pm

bloq wrote:P.S: Would you share your drawings or are they top secret?

As far as i know there have been two others that build the laser i designed. They used my drawings too, so there is nothing secret about.. I designed and build more machines and even started a topic on how to build a decent CNC-router on the CNCZone.NL forum. I drew all parts and electronic-cabinet specially for others (as i have a good machine for many years already) Free!.. If you understand Dutch it is really worth reading those pages..(when you plan to build a GOOD CNC-router, unlike the diy-crap you see on other sites..)

bloq wrote:Does the fact that the reduction of the acceleration works speak for a backlash issue?

Theoretically not, it has more to do with beltstretch, deformations of the structure (if not too rigid) and something i don't know.
Backlash is always there (if there is backlash) independent of the speed and acceleration. Think of a bolt and nut: when you turn the Bolt one way, how much do you have to turn it the other way till the nut starts moving again?, maybe a quarter of a rotation.. translated in backlash this would be 1/4 rotation x threadpitch.

Kees
Techgraphix
 
Posts: 122
Joined: Fri Feb 24, 2012 8:37 pm
Location: Appelscha, NL

Re: Backlash compensation > does not compensate enough

Postby bloq » Thu Dec 17, 2015 7:34 am

As far as i know there have been two others that build the laser i designed. They used my drawings too, so there is nothing secret about.. I designed and build more machines and even started a topic on how to build a decent CNC-router on the CNCZone.NL forum. I drew all parts and electronic-cabinet specially for others (as i have a good machine for many years already) Free!.. If you understand Dutch it is really worth reading those pages..(when you plan to build a GOOD CNC-router, unlike the diy-crap you see on other sites..)


ahh sounds good. And where can i get the drawings :-)? A better cnc router sounds awesome. I do own a enlarged shapeoko but a really good machine would be an option. My wife speaks dutch so she could help me i guess. Where do i find the right thread?

Theoretically not, it has more to do with beltstretch, deformations of the structure (if not too rigid) and something i don't know.
Backlash is always there (if there is backlash) independent of the speed and acceleration. Think of a bolt and nut: when you turn the Bolt one way, how much do you have to turn it the other way till the nut starts moving again?, maybe a quarter of a rotation.. translated in backlash this would be 1/4 rotation x threadpitch.


Deformation of the structure sounds like an option. The blue metal gantry part with the nema on it tends do flex a bit. I think this could already be enough. I guess i have to look into an option like the one you made for your laser.

tm
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Re: Backlash compensation > does not compensate enough

Postby Techgraphix » Thu Dec 17, 2015 8:59 am

bloq wrote:. Where do i find the right thread?

http://www.cnczone.nl/viewtopic.php?f=8&t=7881&hilit=opensource

For drawings of the laser: I plan to make these in DXF-format and a bit more readable for others.. but As they are, I can send you a copy right now.. Send me you mailaddress..

Kees
Techgraphix
 
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