Steel core belts

Just a Quick Question does anyone here know where i can purchase steel core belts for my shapeoko 3

I got them at the link in this thread: Steel-Core Belt Upgrade

They’re shipping with current machines, and in the current Maintenance Kits.

1 Like

So, that seems to be a switch.

Does this include the Z Belt as well in the Maint. Kit?
The open ended steel core belts are somewhat readily available (albeit usually from China) but the closed loop are a bit more difficult to source…

It’s my understanding that due to how they are manufactured it’s not possible to source the closed loop belts with steel cores.

1 Like

Nope, we looked into it around a month ago and were not able to get good quality closed loop belts with steel cores.

We are also regularly checking


You can however buy open ended 6mm steel core belt stock and make one of these. Or even upgrade to 9mm of you’re feeling chippy :grin:


Or upgrade to a ZPlus or HDZ…


Would upgrade to a plus if they would get them in


Does this mean if I received my machine in late December it will have the steel core belts?

Wish there was someplace I could buy one of those :wink:

The design was based off of readily available parts :wink:
Its easy, already prototyped and tested.

LEZHI 5pcs 2GT Timing Belt Aluminum Gear Clamp Mount Block Pack


I’m not near my machine to look and try to figure why yours is shaped as it is, but any concerns with ordering a set of those clamps, sandwiching 2 together with a bolt through and bob’s my uncle?

This looks like a great beginner’s aluminum project, but I’m not quite there yet.

Back in the SO1/2 days folks did belt clamps out of plastic, carbon fiber, and a variety of other materials — I don’t see a reason why even HDPE couldn’t be made to work for this.


Hi Matthew,

You also need to fix the “belt clamp” to the frame of the machine - that’s why @Vince.Fab has those tapped holes.

If you had access to a 3D printer, you could probably print up the back bit, or if your S3 is still functional, mill something up fairly easily.

1 Like

Ah, ok – looking again at @Vince.Fab 's image he does have it laid over where the fixed pulley used to be.

1 Like


I’ve about depleted my supply of steel belts. Been using them for about a year and a half. Will be switching to kevlar reinforced.

My experience has been the steel belts seem to become work hardened in the sections that are most used I.e. if you tend to work your projects in the same general area of your wasteboard. At first they appear to twist up a bit even though still quite tight. I’ve learned this is the time to replace them.

So, it’s nice to not have to deal with belt stretch and recalibration every few months. But, for me, I don’t get as much use out of steel belts. We’ll see how the kevlar belts work out.

One final note, I suspect there may be a range of quality from the various suppliers. I only sampled one.


There is a much smaller window for proper tension on the steel cores. Ive had very good luck running a little on the "loose"end of the scale.

Any twisting indicates partial core failure and they require a daily inspection. My belt life is at least 8 months per set and have been able to hold sub 0.005 tolerance without step adjustments.

Big crashes might have a part in belt life. This might be where the kevlar shines. Interested to hear your thoughts on them @griff and I’ll probably order some soon too.


Gates claims “The entire PowerGrip® GT®3 belt range is suited both for new drive designs as for performance upgrades on existing drives. It has two times the rating of competitive RPP® belts and its predecessors PowerGrip® GT® and HTD®, with the largest selection of belts and sprockets in the industry.” Has anyone tried/evaluated them (or even Gates brand GT2 belts)?