New fixed motor movement system? So, I was derping around looking at Core XY machines to build (Specifically HyperCube EVO), and I started to think "Hey, crossing belt CoreXY is nice and all, but the belts getting misaligned is a bit of a pain". Then I also looked at the HEVO's approach but noticed that not crossing the belts induces a torque onto the extruder assembly. So, I thought, "Hell, why not try to design a new system?". And thus after a bit of tinkering I made this: 1USuvGc.png mod_embed_images_loadimage('921ecffd33cfe78e97847e26b0587ab3', '/forum/thumbcache/244/c06/d01/9f6/c69/a3f/c4f/fdc/f03/3d8/d3_800x400.png', 'https://i.imgur.com/1USuvGc.png', 'https://reprap.org/forum/addon.php?152,module=embed_images,check_scaling=1,url=https%3A%2F%2Fi.imgur.com%2F1USuvGc.png', '', 832830, 800, 400, 'Loading image ...', false); The main idea here was to balance the forces as much as possible. Since the gantry is connected to opposite symmetrical points, as well as at the same level of the center of mass, the rotation alongside the X axis should be non-existent. Then there's the X carriage, which is connected right at the center to reduce all rotations along the Y axis. This in turn would allow the use of rods without having to worry much about lubrication or binding. I'd like to receive any and all feedback, as this would really help me decide weather it's worth trying to build something like it or not. https://reprap.org/forum/read.php?152,832830,832830#msg-832830 Sun, 17 May 2026 17:56:21 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?152,832830,833848#msg-833848 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,833848#msg-833848 Trakyan General New Machines Topics Sun, 16 Sep 2018 22:59:19 -0400 https://reprap.org/forum/read.php?152,832830,833088#msg-833088 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,833088#msg-833088
Quote
the_digital_dentist
Do these "unbalanced forces" cause problems?

With careful positioning of pulleys, a single-level corexy mechanism could be made free of "unbalanced forces", I think.

OTOH< if you want to try to come up with a new belt layout...

Depends on what motion system you use, but for rods and extrusion rails they can cause problems. Not so much with linear rails due to the tolerances they're made at.

And yes, a crossing belt CoreXY can be made balanced, but the crossing of belts and the fact you use a single motor to move in two axis is what I don't like about CoreXY]]> Heracles421 General New Machines Topics Fri, 07 Sep 2018 09:14:39 -0400 https://reprap.org/forum/read.php?152,832830,833046#msg-833046 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,833046#msg-833046
With careful positioning of pulleys, a single-level corexy mechanism could be made free of "unbalanced forces", I think.

OTOH< if you want to try to come up with a new belt layout...]]> the_digital_dentist General New Machines Topics Thu, 06 Sep 2018 22:24:09 -0400 https://reprap.org/forum/read.php?152,832830,833032#msg-833032 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,833032#msg-833032
Quote
o_lampe
Now it seems right, but the kinematic is a mix of H-Bot and CoreXY.

dX = dA ( red belt )
dY = -dA + dB ( blue )

I don't know if it's worth adding extra length to the blue belt and get more stretch/ringing there, just to fight extruder tilt. ( which is neglectible when using linear rails and carriers)

edit: I just saw that both belts are equal length, so forget my above comment. It's even worse: both belts are extra long which is a big trade off IMHO.

Yea, that's the one downside I can see to it, belt stretching and adding inconsistency. I wanted to use something like this for linear bearings more so than rails.
I can't think of a way to make the belt any smaller while keeping them in a cartesian-esque configuration...

Edit: Actually, now that I look at it, the belt lengths are exactly the same as with either an H-Bot or a CoreXY, the only difference being you have to sets of belts (one for each axis) rather than a single belt for both, but it shouldn't really be that much different from either configuration. If anything the belts need to stretch less as they endure half the force. However, I just noticed that having that H-Bot esque config beats the whole purpose of this system, as it applies a torque on the frame...

Quote
the_digital_dentist
What problem is being solved here?
Trying to figure out a belt system that has a cartesian configuration (unlike the h-bot and coreXY) so that there's no unbalanced forces being applied where you don't want them to (for example, rotational forces), but without having the motors move like in a traditional cartesian configuration]]> Heracles421 General New Machines Topics Thu, 06 Sep 2018 18:07:33 -0400 https://reprap.org/forum/read.php?152,832830,832999#msg-832999 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,832999#msg-832999 the_digital_dentist General New Machines Topics Thu, 06 Sep 2018 11:37:59 -0400 https://reprap.org/forum/read.php?152,832830,832943#msg-832943 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,832943#msg-832943 
dX = dA ( red belt )
dY = -dA + dB ( blue )

I don't know if it's worth adding extra length to the blue belt and get more stretch/ringing there, just to fight extruder tilt. ( which is neglectible when using linear rails and carriers)

edit: I just saw that both belts are equal length, so forget my above comment. It's even worse: both belts are extra long which is a big trade off IMHO.]]> o_lampe General New Machines Topics Thu, 06 Sep 2018 00:47:01 -0400 https://reprap.org/forum/read.php?152,832830,832902#msg-832902 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,832902#msg-832902




]]> Heracles421 General New Machines Topics Wed, 05 Sep 2018 13:56:45 -0400 https://reprap.org/forum/read.php?152,832830,832872#msg-832872 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,832872#msg-832872
Hmm, after giving it a second look I now notice this is totally flawed... Back to the drawing board]]> Heracles421 General New Machines Topics Wed, 05 Sep 2018 07:46:31 -0400 https://reprap.org/forum/read.php?152,832830,832844#msg-832844 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,832844#msg-832844 VDX General New Machines Topics Wed, 05 Sep 2018 02:48:15 -0400 https://reprap.org/forum/read.php?152,832830,832834#msg-832834 Re: New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,832834#msg-832834
There's an error in your drawing.
I marked the belt in question with a red arrow. It is fixed in length and hinder the gantry to move 'down' or it'll go slack, when moving 'up']]> o_lampe General New Machines Topics Wed, 05 Sep 2018 00:54:10 -0400 https://reprap.org/forum/read.php?152,832830,832830#msg-832830 New fixed motor movement system? https://reprap.org/forum/read.php?152,832830,832830#msg-832830
And thus after a bit of tinkering I made this:


The main idea here was to balance the forces as much as possible. Since the gantry is connected to opposite symmetrical points, as well as at the same level of the center of mass, the rotation alongside the X axis should be non-existent.
Then there's the X carriage, which is connected right at the center to reduce all rotations along the Y axis. This in turn would allow the use of rods without having to worry much about lubrication or binding.
I'd like to receive any and all feedback, as this would really help me decide weather it's worth trying to build something like it or not.
]]> Heracles421 General New Machines Topics Wed, 05 Sep 2018 00:19:24 -0400