Overengineered CoreXY

Why would you need a gearbox for Z? If you use common 20T pulleys on motors and some big 60T on Z ballscrews you get a 3:1 "gearbox". For 16T motor pulleys, even bigger ratio.

Quote
anvoice
Here's a redesigned version of the printer as I have it so far. Now it uses 3 ballscrews and 2 linear guides for the Z, as well as dual 608 bearings for pulleys to accommodate 10mm belts on the XY. Haven't figured out what sort of gearbox I'll drive the Z with but I'll do a bit of research and probably manage.

[attachment 91056 coreXY_v1.jpg]
[attachment 91057 coreXY_v1-2.jpg]

Especially appreciate all of your feedback that helped make some positive changes.

I'm using a common belt on my screws. 18-tooth drive pulley and 36-tooth driven pulleys. Find the belt you want to use 1st. The largest GT2 (2mm) belt I can find is a 2.2 meter loop.

I would put both Z-slides on the same wall with the single lift screw the middle. Easier to align.

Also, that single X rail needs some additional material in the X-Y plane to keep it from ringing. An angle attached to the back of the rail would do it.

For a pretty elegant design you might take a look at the pictures and links from this thread:

[groups.google.com]

Also, I've got some pictures posted in this thread:

[groups.google.com]

Cheers,

Mark Napier

Edited 1 time(s). Last edit at 02/23/2017 08:46AM by napierm.

Quote
sigxcpu
Why would you need a gearbox for Z? If you use common 20T pulleys on motors and some big 60T on Z ballscrews you get a 3:1 "gearbox". For 16T motor pulleys, even bigger ratio.

I believe 60T pulleys won't fit on the screws without extending outside the frame, which means I can't enclose it.

Edit: Actually I think you're right, it fits nicely and will probably provide enough of a geardown to drive the axis. Thanks for the idea. Just ordered some 60T and a 16T pulley, that should give enough reduction and a nice number for the steps/mm.

Edited 2 time(s). Last edit at 02/23/2017 11:36PM by anvoice.

Quote
napierm

Quote
anvoice
Here's a redesigned version of the printer as I have it so far. Now it uses 3 ballscrews and 2 linear guides for the Z, as well as dual 608 bearings for pulleys to accommodate 10mm belts on the XY. Haven't figured out what sort of gearbox I'll drive the Z with but I'll do a bit of research and probably manage.

[attachment 91056 coreXY_v1.jpg]
[attachment 91057 coreXY_v1-2.jpg]

Especially appreciate all of your feedback that helped make some positive changes.

I'm using a common belt on my screws. 18-tooth drive pulley and 36-tooth driven pulleys. Find the belt you want to use 1st. The largest GT2 (2mm) belt I can find is a 2.2 meter loop.

I would put both Z-slides on the same wall with the single lift screw the middle. Easier to align.

Also, that single X rail needs some additional material in the X-Y plane to keep it from ringing. An angle attached to the back of the rail would do it.

For a pretty elegant design you might take a look at the pictures and links from this thread:

[groups.google.com]

Also, I've got some pictures posted in this thread:

[groups.google.com]

Cheers,

Mark Napier

Looks interesting.

I'm thinking I'll take the challenge of aligning the Z-rails as is because this way should be a bit stiffer overall.

I'm going to look for a closed loop belt next. Curious: has anyone found a 10mm wide closed loop belt. So far I'm only hitting 6mm wide, or does it not matter much for Z?

I was thinking of adding material to the X axis, but thought the 20mm rail should be more rigid than any light piece of metal I can attach to it. Maybe that's wrong.

Edited 1 time(s). Last edit at 02/23/2017 04:41PM by anvoice.

AFAIK, there are 6 and 9mm GT2 belts?

X-Axis: the steel rail combined with a stiff aluminum angle would reduce resonance because of two different materials.

I have 10mm wide (calipers say 11mm) pulleys and what was declared to be 10mm wide belt coming from Aliexpress, so I'm guessing 10mm is an option, unless it's actually 9mm marketed as 10mm.

I'm convinced. Added an aluminum angle (1/8") to the X axis.

Edited 2 time(s). Last edit at 02/24/2017 05:29PM by anvoice.