3GT Belts and Pulleys

My X/Y belts for my CoreXY design will be approx 3meters each (very large build). Thus I'm looking into 3GT belts for added stiffness, particularly 9mm width, but am having a couple issues that leave me to questions that seem hard to answer by my best friend, Go Ogle.

1) It seems impossibly hard to find toothed 3GT idlers, especially 9mm width. Misumi has them but are insanely expensive. Anyone know where else I can find these things at decent price? I believe I need 8.
2) I was reading that 3GT belts have more (4x as much) backlash as 2GT. This surprised me since both have rounded teeth. Is this true? Is there space between the teeth of the pulley and the teeth of the belt, or what leads to this? Is it true that when properly tensioned, this goes away or becomes negligible, as I would think would happen?

These 2 problems/questions are leading me to just going with a 9mm wide 2GT belt instead, but am not sure if that would stretch and cause noticeable deviations/artifacts in my prints.

Bonus question: I read somewhere that said pulleys for 2GT and 3GT are the same, but I can't wrap my head around how that possibly could work with different tooth size and pitch. Is there any shred of truth to that, and if so, how could you possibly run a 3GT belt on a 2GT pulley without excessive tooth wear at the least?

Cheers

Can you post a link to the GT3 data you read regarding backlash?

Also note the "3" in GT3 or the "2" in GT2 does not refer to the pitch, it refers to the tooth profile series. (You can actually get 3MM pitch GT2 belts.) The tooth pitch is called out separately.

Edited 2 time(s). Last edit at 05/11/2017 01:11PM by LoboCNC.

GT3 belt is just an improved version of GT2 belt - both are made for GT2 pulleys.

So as I understand it, GT2-2M belts are also known as 2GT belts and are GT2 belts with 2mm pitch and is total 1.38mm thick (dimensions shown here, but can be found elsewhere as well: [openbuildspartstore.com] )
As I understand it, GT2-3M belts are also known as 3GT belts, and are also considered GT2 belts with 3mm pitch. They also are thicker with total 2.40mm thickness, some is in the actual belt thickness and some in the larger teeth size.
Am I correct so far?

Now, if a 3GT belt is different thickness, pitch, tooth size, etc, than 2GT, how can they possibly use the same pulley? I feel like the teeth on the pulley would clash with the belt teeth. If I am correct on this, where can i get 3GT pulleys?

On my other note of 3GT having more backlash, I've seen it on a couple different sites. Here is one: [www.shapeoko.com]

And since GT3 was mentioned...is there a difference between 3GT belts and GT3 belts?

Hallp! haha thanks.

I haven't seen many places that use the nomenclature 2GT - almost everyone uses GT2 which is the designation Gates uses (GT is a Gates trademark). I believe Gates refers to the belts as GT2-2mm, GT2-3mm, GT3-2mm or GT3-3mm.

Here is a good place to look for GT3 pulleys. They're called GT2-3mm as mentioned above.

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o_lampe
Here is a good place to look for GT3 pulleys. They're called GT2-3mm as mentioned above.

Trying to avoid plastic bearings. Much appreciated though.

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shortyski13

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o_lampe
Here is a good place to look for GT3 pulleys. They're called GT2-3mm as mentioned above.

Trying to avoid plastic bearings. Much appreciated though.

Why? They are more than adequate for the loads a printer will be putting on them.

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etfrench

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shortyski13

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o_lampe
Here is a good place to look for GT3 pulleys. They're called GT2-3mm as mentioned above.

Trying to avoid plastic bearings. Much appreciated though.

Why? They are more than adequate for the loads a printer will be putting on them.

I thought they would wear out very quickly and wouldn't be very precise. I could be wrong. Plus they aren't shiny ;-)

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shortyski13

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etfrench

Quote
shortyski13

Quote
o_lampe
Here is a good place to look for GT3 pulleys. They're called GT2-3mm as mentioned above.

Trying to avoid plastic bearings. Much appreciated though.

Why? They are more than adequate for the loads a printer will be putting on them.

I thought they would wear out very quickly and wouldn't be very precise. I could be wrong. Plus they aren't shiny ;-)

You're right, you are wrong

I found that 3GT belts can be used with HTD-3M pulleys, so I will use those for the idlers and 2GT-3M drive pulleys, since those I can find. Just FYI for anyone with the same predicament and were debating using a smooth idler (which I'm opposed to).

These and also these don't seem to be terribly expensive.