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GT2 belt types

Posted by animoose 
GT2 belt types
March 16, 2018 12:35AM
Is there any reason to prefer fibreglass core GT2 belts over steel wire core ones, or the other way round?

Also, do belts tend to deteriorate over time? The belts in my CoreXY printer seem to have become much slacker over a short period of time, but I can't see any other mechanical reason for this. This is on a printer I haven't used much for a while.
Re: GT2 belt types
March 16, 2018 03:14AM
Don't run steel core belts over small pulleys, because the steel cores will fracture if you do.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: GT2 belt types
March 16, 2018 02:05PM
I've tried a few belts and basically steel is good and very inelastic compared to neoprene/fibreglass, but yes 16t and even 20t pulleys will fatigue the wires especially with 180 belt path. 30+ tooth pulleys are better but that's resolution lost in favour of stiffness.

I've got some genuine gates 2gt power grip 6mm belts on my kossel Xl and it really makes no difference. Buy ebay belts with confidence, make sure they're tight but don't go crazy.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
Re: GT2 belt types
March 16, 2018 04:54PM
Quote
DjDemonD
I've got some genuine gates 2gt power grip 6mm belts on my kossel Xl and it really makes no difference. Buy ebay belts with confidence, make sure they're tight but don't go crazy.

Maybe not with complete confidence. I started off with some generic e-bay belting on a fairly large H-bot printer (350x350mm), but then bought some genuine Gates belting that was both measurable stiffer (I did some testing off of the printer) and produced better quality prints (less ringing evident in the surface finish). I may have originally purchased some particularly cheese-ball belts, but the problem is you never know.

I just bought some steel core belting and will attempt to run it over 18t pulleys. I kind of suspect they will fatigue and break, but I'm curious to find out how long they'll last.
Re: GT2 belt types
March 16, 2018 05:10PM
Well, I had 16t pulleys on my kossel XL which originally had PU/steel belts when I built it Sept 2016, by Christmas the belts were fatiguing causing a very odd issue that I couldn't track down for days. I also installed them on my corexy with 20t pulleys, they lasted longer maybe 5-6 months, no drama when they failed as I noticed it pretty quick and knew what to look for. I'm sure you could reduce the fatigue if you engaged fewer teeth via some clever idlers.

It would be interesting to do some real testing to measure the whether slightly less resolution (bigger pulleys) would be compensated for by stiffer belts.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
Re: GT2 belt types
March 16, 2018 05:19PM
Fiberglass and steel belts have very similar elastic modulus. Steel is generally preferred for shock resistance. As far as I am aware Gates does not make steel reinforced gt2 or gt3 series belts.

[www.sdp-si.com] Page 12

Its hard to make any claims about timing belts because until you spend $$$ you don't really know who made the belt/pulleys or if they are even the correct profile.

Edited 1 time(s). Last edit at 03/16/2018 05:20PM by 691175002.
Re: GT2 belt types
March 17, 2018 03:34AM
If I'd build a CoreXY again, I might think of using steel core belts and bigger pulleys/idlers. But add a short, closed loop rubber belt gearing to compensate the resolution-issue.
The motors are outside the frame for easier enclosing.

Q: Would the steel core belt live longer, if they had a quick release belt tensioner? They would only be stressed while in use and can rest when the printer is idle.

Edited 1 time(s). Last edit at 03/17/2018 03:40AM by o_lampe.
Re: GT2 belt types
March 17, 2018 04:32AM
Certainly using bigger pulleys, and then a reduction to restore the resolution would make quite a nice solution.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
Re: GT2 belt types
March 17, 2018 10:06AM
Quote
o_lampe
If I'd build a CoreXY again, I might think of using steel core belts and bigger pulleys/idlers. But add a short, closed loop rubber belt gearing to compensate the resolution-issue.
The motors are outside the frame for easier enclosing.

Q: Would the steel core belt live longer, if they had a quick release belt tensioner? They would only be stressed while in use and can rest when the printer is idle.

Excessive flexing around a small radius of curvature is what breaks the steel core wires, not tension.

I used 22 mm diameter pulleys (larger than what most people use) in UMMD and briefly tested steel core GT2 belts for the XY stage. Actually, I should say I started to test them, and as soon as I put one on the machine, I took it off and didn't bother with it again. Steel core belts take quite a bit of energy to bend around the pulleys. All the extra effort to bend around multiple pulleys in a corexy stage has to be provided by the motors. In corexy the belt has to bend around 4 pulleys. I found it difficult just to tension the belt because of its stiffness.

For the Z axis, steel core seems to be fine. I currently have steel core HTD-3M belts on UMMD. I'm waiting for some new pulleys to arrive from China and will convert to steel core GT2.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: GT2 belt types
March 20, 2018 06:00PM
Some types of belts are available with kevlar reinforcements. Very high tensile and softer than steel going around pulleys. However they do not tolerate being pinched tight which will break the fibers.
Re: GT2 belt types
March 21, 2018 08:38AM
Got any links? I've tried hard to find these mythical kevlar reinforced belts with no success, perhaps I'm not good at finding things.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
Re: GT2 belt types
March 21, 2018 09:02AM
Quote
Dj
Got any links? I've tried hard to find these mythical kevlar reinforced belts with no success, perhaps I'm not good at finding things.

this it ?
Re: GT2 belt types
March 21, 2018 09:52AM
Possibly, I've bought "kevlar reinforced" belts and they were just fibreglass and being oversold. But worth a shot.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
Re: GT2 belt types
March 21, 2018 10:40AM
$4 per foot? Ouch!


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: GT2 belt types
March 21, 2018 03:29PM
Quote
DjDemonD
Possibly, I've bought "kevlar reinforced" belts and they were just fibreglass and being oversold. But worth a shot.
How did you see it was fiberglass ?


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: GT2 belt types
March 22, 2018 08:39AM
I stretched it and it stretched the same amount as the previous eBay special belt which was sold as fibre/neoprene. So I presumed it was not any "superior" material. It wasn't particularly expensive £3.99/meter.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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