9mm 3GT2 belting

I did 9mm gt2 belting more than a year ago, Haven’t had skip or miss since. Took a little effort to find pulleys the same shaft size and diameter but they are out there. I think openbuilds has them. This was the best upgrade I have done. Made the end brackets with my X-Carve out of a piece of flat aluminum and bolted them to the 6mm brackets with a slightly longer screw. You will be very happy.


I got mine from OpenBuilds. The idler’s that they sell also fit the 9mm belts.

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Which ones did you purchase?

Also how did you attach the belts and tension them?

Looking back, I should have bought the 9 mm pulley’s and idler’s from the start even though I’m running the 5 mm belts.

How many belt did you buy Phil 2 or 3?

Phil, Do you notice much difference in the quality of the 15xx belts vs the ones you got from ebay ?

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Is the flat pattern for these possibly available? I will need these for my new belts as well.

Aside from Phil’s nice end clips, how are people attaching the larger belts? i’m stuck on this step in my upgrade currently.

I read somewhere that a guy just used a file and widened the existing clips. I’m doing mine this week and that how I planned to do it.

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I’ll try that, but I was looking at it yesterday and my belts are practically the width of the clip. there may not really be any material left by the time you make it wide enough for the belt. I’ll give it a try though.

The clips themselves are 12 mm wide. The slots from Inventables are 7 mm wide, which leaves 2.5 mm on each side. For 9 mm belts, you’d need to file at least 1 mm on each side to fit the width. Not sure if you’d need to expand them if you’re using a different pitch or not, the holes are 2.75 mm wide.

These are per the drawing. It’s also powder coated finish which may change those values. I’m assuming the dimensions are pre-coating so the coating takes away some of the available space.

I’m definitely going to upgrade belts!!
Tried finding length on the belts you posted a link to Phil, but can’t find one. What length is the belt?

The ones from Royal Supply are 1500mm. the Ebay belts are by the foot.


Thanks! I’ll be ordering my stuff next week hopefully.

If you have access to a 3D printer these clips work very well. I have been using them since I went to the 9mm belts.

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I did that with mine and they are still holding strong. I used a dremel with a thin grinding tool to enlarge each clip. I also routed the belts a little differently than normal but it’s still teeth on teeth underneath the front of the clip. The photo shows them securing 9mm 2GT belts but I have since upgraded the belts to 3GT and it still works.

Hey @PhilJohnson… it looks like you kept the same spacers on the wider smooth pulleys, which I think brings them just slightly out of alignment with the tensioners. I doubt it would matter though… have you seen any adverse effects? Apologies if you commented on this already and I missed it.

Thanks, question was about the smooth pulleys though, not the geared ones.

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True, fair point. Thanks!

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