26 Reply by pretenda

  • pretenda
  • pretenda
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  • From: Sydney, Australia
  • Registered: 2012-10-13
  • Posts: 173

Re: Dual "Y" drive motors

Hazer wrote:

I will add to that: Since HBOT has a single belt, belt tensioning has less of an impact on the system (perfect circles). The bad thing is the X axis flexing out of square. As the distance between ends increases, the linear rods have less chance of being able to keep the axis square to the Y axis with fast movements. A good compensation for this is using linear rails instead of rods.

A COREXY has the benefit of using the tension of the two separate belts to counter-act the problem with keeping the X axis square, but requires both belts to be perfectly tensioned to each other.

I prefer HBOT on the merit that it is easier to setup. You can use proper design to keep your axis square, and the single belt makes taking things apart repeatedly much easier. You dont have to tighten the belt at the ends either, if you put oblong mounting holes for the motors so you use the motor to tighten the belts (like the Y motor on the SD).

Here is a good illustration of an HBOT:
http://www.thingiverse.com/thing:161000

Great info. Makes sense as to why h bot is a bit more popular at the moment. One other small thing, coreXY can be tensioned in the same way (with the motor mounts being elongated that is.

27 Reply by rsantos

  • rsantos
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  • Registered: 2016-02-18
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Re: Dual "Y" drive motors

pirvan wrote:

I was looking over Wompus's post where he moved the "Y" stepper motor outside the case and put it in line with the drive rod, and this got me thinking...

Has anyone considered using 2 stepper motors to drive the "Y" belts directly?  There are at least a couple of ways of mounting the motors.

One would be from the outside of the frame with the shafts sticking inside (would require motors with longer shafts).  Another way would be to make some kind of mounting bracket (plastic or metal) that would let us mount the motor on the inside back face, with the shafts pointing towards the left and right side.

The big question is whether or not we could drive the 2 motors from the same output port. 

Hopefully some of the electronics wizards here might be able to chime in on this.  Can the stepper drivers handle 2 motors?  And this question pertains to both boards, Sanguinololu and Printrboard.

For future reference about this approach see here:
http://www.soliforum.com/topic/15753/so … tor-drive/

- Graber/Prusa I3 remix - Arduino Mega/Ramps 1.4 - Upgrades: Auto Bed Leveling, PEI bed, All Metal E3D V6, Filament detector
- Alted's MPCNC - 24" X 24" plate - Arduino Mega/Ramps 1.4 - DeWalt 660, TFT28 display
- Solidoodle 4 -  with Y axis Dual Motor Drive (own design), Lawsy carriage remix, chrome hardened smooth rods, bed stabilizer, GT2 belts
http://www.thingiverse.com/3dEz/about