Must have SO3 Upgrade

So recently I was working on a project and had a belt break. Although it destroyed the project, it gave me an opportunity to reach out to look for some upgrades. Thanks to the good folks here for all their help!

Although I have heard of people going with a 9 mm belt upgrade, that just was not enough for me. I went for a 10 mm belt. Boy was I happy I did. I purchased the belts and pulley from Amazon. These fit the SO3 perfectly. It was plug and play!** No other modifications needed. I replaced both x & y belts with these 10 mm belts. I have heard that it will not fit the Z axis. I have not had the opportunity to try the Z, but will in the near future. I will report my findings here when I do.

Overall This was a great cheap upgrade. Cuts are cleaner, and over all the machine is stronger. Belts last longer and less belt stretch over time. I highly recommend this upgrade to all SO3 owners. I would encourage Carbide3D to make this a standard for any new SO3 purchasers. Hope this helps, Keep on cutting yo!


FWIW, people started doing this sort of thing back in the SO2 days.

I went w/ SDP/SI though: and suspect (hope?) better quality > 11.11% wider.

9mm wide belts at least are standard as of Jan. 2016:

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Thanks for putting this information together and sharing it,really looking forward to your Z findings :slight_smile:

Just out of curiosity, what did you use to clamp down the belt ends, since wider clamps aren’t included in the Amazon kit??

The stock clamping systems will accommodate wider belts — I used them on my 9mm upgrade.

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Will is correct. I just used the stock clamps for this. It works just fine for 9mm or 10mm.

Is there any specific improvement gained from fattening these belts? I mean, sure, bigger seems better, but is there any measurable increase in any specific parameter like tension consistency, lifespan, or anything?

We have the specs for 6mm here: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable

And the following note:

TL;DR for this page: The GT2 belts that come with the machine are very accurate if properly tensioned and the only other belts you should consider to handle more force are either the same 2M GT2 in wider width (+55% modulus @9mm wide) or 3M GT2 for maximum stiffness at the expense of precision (+325% modulus @15mm wide, 4X-5X backlash).

So, to restate: A belt upgrade might increase the maximum stiffness, which is not particularly necessary, at the expense of increased backlash?

Is there any specific indicator that someone might need the machine to handle more force? Just wondering, especially since the post title notes this is “must have,” thanks

If you stick with the 9mm belts there is no increased backlash. I think that’s the sweet spot.

Going to 15mm belts with more backlash seems like overkill to me.

Sweet spot for what, though? What is the gain?

The belts are stiffer and can be tensioned more. Wider belts have more contact area on the pulleys so they are less likely to slip/jump teeth.

I do agree with your doubts that this is a “must have” update, but it’s not expensive to do.

Just a quick warning / PSA from Carbide- we don’t recommend tensioning the 9mm any more than you would tension the 6mm. Even the 6mm can withstand more than enough force to bend a motor shaft. Don’t ask how we know that…