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Weird issue with corexy

Posted by emielvs 
Weird issue with corexy
September 07, 2018 12:39PM
Hi Guys,


I'm converting my crappy leapfrog creatrthumbs down to a corexy machinethumbs up.

But I'm having a really strange issue with it. The same as this YouTube video: [www.youtube.com]

I don't know how he fixed it what do you guys think?


Thanks
Re: Weird issue with corexy
September 07, 2018 03:36PM
Do you have the same size pulleys on both motors?

Are you sure?

Are the X and Y steps/mm set the same in the firmware? Are they set differently in a config over ride file somewhere?

Edited 2 time(s). Last edit at 09/07/2018 03:49PM by the_digital_dentist.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Weird issue with corexy
September 07, 2018 03:47PM
Can you post some pictures of the key parts of your CoreXY mechanics? Motors, belt mounts, carriage, idlers etc...
Re: Weird issue with corexy
September 08, 2018 04:51AM
Yes I counted the 2 pulley's in the back twice. they have 16 tootrh

I'm running the printer with a re-arm(smoothieware on it) with a ramps converted to 24V and on the X&Y i have TMC2100 stepper drivers (In spreadcycle). Attached my config files en config override.

And hereby some images of my printer.







My previous design was running the same (Re-arm, 24V, TMC2100 etc) and was running fine. So I'm suspecting it's in the cartesian system.
Attachments:
open | download - config 8-9-2018.txt (30 KB)
open | download - config-override 8-9-2018.txt (1.3 KB)
Re: Weird issue with corexy
September 08, 2018 08:11AM
I like the way you routed the belts and the tensioning using the adjustable pulleys in the motor mounts. Very nice, except that it's an awful lot of pulleys for the motors to have to bend those belts around. It looks like you're using steel core belts. I suspect the pulleys are too small and that will lead to the steel cables inside the belts breaking. Then the belts will stretch in the areas where the cables are broken and that will cause all sorts of mysterious problems with print quality. Maybe the cores are already broken?

The config file and the over-ride file look fine (I just looked at them for the stuff that controls the motion- there could be other problems). The config file used to have a parameter that controlled the pulse duration to the stepper divers, but they seem to have taken that out. I wonder if there is some problem with the pulses being too short for the external drivers/cables to them.

I'm not a big fan of config-overrides. I'd suggest putting whatever is in there into the main config file and deleting the over-ride file, once you have all the settings worked out.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Weird issue with corexy
September 08, 2018 02:38PM
Quote
the_digital_dentist
I like the way you routed the belts and the tensioning using the adjustable pulleys in the motor mounts. Very nice, except that it's an awful lot of pulleys for the motors to have to bend those belts around. It looks like you're using steel core belts. I suspect the pulleys are too small and that will lead to the steel cables inside the belts breaking. Then the belts will stretch in the areas where the cables are broken and that will cause all sorts of mysterious problems with print quality. Maybe the cores are already broken?

The config file and the over-ride file look fine (I just looked at them for the stuff that controls the motion- there could be other problems). The config file used to have a parameter that controlled the pulse duration to the stepper divers, but they seem to have taken that out. I wonder if there is some problem with the pulses being too short for the external drivers/cables to them.

I'm not a big fan of config-overrides. I'd suggest putting whatever is in there into the main config file and deleting the over-ride file, once you have all the settings worked out.

Aah damn indeed on some places the steel core was already broken! Changed it to my old gt2.5 belts and it works!!!smileys with beer Thanks for your helpthumbs up

So now waiting on a my new GT2 belts, finishing the design and then it will be on thingiverse and youmaginehot smiley

If someone has any feedback on the design to improve your more than welcome to share with mesmileys with beer
Re: Weird issue with corexy
September 08, 2018 09:06PM
This is a very nice looking design. Congratulations on fixing your problem.
Few notes:
- On X you are not using X rods to fight belt tension so Y rods are getting bend force to fight belts. You may engage X rods to resist bending forces.
- Location of the X endstop may be changed to increase X printable room. Now you are subtracting the size of endstop sensor from X dimension.
- Belt tensioning mechanism may be improved if you will create a separate fixture for each belt.
- If you will move motors closer to the vertical extrusion you may not need one of the idlers, and use corner idler instead of the second idler on the motor mount and still use almost al curvature of the pulley.

Overall nice work.
Re: Weird issue with corexy
September 09, 2018 03:02AM
Looks good!
I think the clamps for the X-rods could be a bit beefier.
Also the brackets for the idlers look like they could suffer from layer separation one day. Is there a chance to change print orentation?
You could also try to decrease the distance from idler to Y-rod. Even if the printer won't gain print volume: the shorter/the better.
Re: Weird issue with corexy
September 11, 2018 12:35PM
Nice bracket designs! What material are you printing them from, plain PLA?

Quote
o_lampe
Also the brackets for the idlers look like they could suffer from layer separation one day. Is there a chance to change print orentation?

I second O_lampe's comment on the layer separation. They would be strongest if printed in the orientation they are mounted. You would also get a tighter tolerance hole to mount the idlers.

What diameter Z lead screws are you using? They look beefy.
Re: Weird issue with corexy
May 06, 2019 06:39AM
Hi EmielVS,

How is it with your upgraded Creatr ?

I have also a old broken Creatr and want to upgrade it with a CoreXY.
I love your design. I like to see some more pictures ;-)

Do you want to share your design ?


Kind regards,
Peter.
Re: Weird issue with corexy
May 06, 2019 08:56AM
Since we're back to this old thread... I noticed that the belt clamp on the extruder carriage looks disturbingly like one I used in UMMD's Z axis. It failed when the rubber part of the belt stretched over the core wires due to the tension on the belt.

The clamp was like this:



And this is what happened:



The new clamp folds the belt back on itself:



That type of belt clamp has been working without trouble in the XY stage for 2+ years, and in SoM's X axis for at least 5 years.

See: [drmrehorst.blogspot.com]


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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