If it’s loose, then it isn’t from a lack of effort is what I’m trying to say. I think it comes down to the (bad) design of the clip.
Any suggestions on improving it or should we just super glue the belt end and then take advantage of the longer length bolt (without bending motor shaft of course). 
Why is your use of that belt tension different than other’s use? Is it that the laser exposes the result of the backlash where the router/spindle masks the problem?
Or, is there still something else causing the problem?
That’s what I’d like to know too. We’re literally at a point where if there’s anyone close in TX willing to help, that would be awesome. 
Someone could make a killing selling belt tensioners.
Do you have a 3D printer?
Yes but it’s been down for awhile. I could pay someone to machine the parts if necessary though Neil.
I could widen these and send them to you, but I’m not convinced that your issue is belt tension.
Cool design! Do you have a photo of them installed? Whatever you’re willing to help with, all is great
I measured about 0.2mm of lost motion on X earlier, and that was after tightening the X stepper mount block, idler bearing bolts, and then belts again.
Would it be caused by no forces on it when using a laser. When using it with a spindle its got some pressure against the piece its cutting in to which maybe keeps a load on the belts.
You may be on to something there actually, my friend said the same thing.
Since the Y axis has two belts, maybe it’s not showing up there as easily, at least to my eyes.
If using a spindle and doing a rapid though and changing direction, backlash could still cause issues.
If there is backlash due to the pulley-belt interface, there’s not much you can do with the open belt drive on the Shapeokos. On the Y, it’s possible to have the pulleys pre-loaded in opposite directions to minimize the backlash. On the X, you’re stuck with one pulley.
Maybe better belts and pulleys? (I’m saying that without knowing what they use)
They’re Powge brand from Aliexpress. I can’t even seem to find something comparable here on a USA website.
Any help would be appreciated if there is indeed a USA source.
I’d still like to try a better tensioner!
I was looking at rack and pinions, and KHK has a tapered rack and pinion setup to where you can slide the pinion in or out to remove backlash.
The racks would clear underneath the gantry and X stepper mount block, but that is a whole other animal for machining an adapter plate to mount the racks perfectly to the Shapeoko extrusions. The ‘finest’ one they offer is 100mm of linear travel per rotation of the motor though, which seems a bit coarse (could be worked around with higher microsteps on the driver?). The idea has me curious at least.
https://www.khkgears.us/catalog/?cid=cp_tapered_pinions_ktscp
https://www.khkgears.us/catalog/?cid=cp_tapered_racks_strcpf-strcpfd
I had a similar issue on my Shapoko 3. The belt would slip through the clip a little bit. I ended up zip tying it so it would stay in place while I tensioned. I’m not sure if you can do that with those extra wide belts; however you could try unbending the clip so it was at more of a 95 degree angle instead of 90. That should give a bit more downward pressure keeping the belt engaged on itself. You could also try to find GT2 belt crimps. You’d lose a bit of travel, but it would let you know if that is truly the problem. If it is you could look into a better solution.
I’d try another belt/pulley combo first.
Maybe this?
PM me your address.
Came across this that may be of interest.
It appears that Gates GT3 (Not 3GT) is the new and better replacement for GT2, with the caveat of going to a 3mm pitch in order to preserve the 15mm belt width. I can get the pulleys with a 1/4 bore from Misumi supposedly.
GT3 will work in GT2 pulleys, but since the pitch is 3mm for 15mm wide belts, I would need to get new pulleys.
If I’m going to go that route, I should get a larger ø pulley in order to have more belt wrap.
It wouldn’t take much to add some “resistance” to your X motion for a test to see it some improvement occurs.
Have you calibrated your steps/mm on X? Your control board, 8 bit or 32 bit?
Yes indeed
So 8 bit or 32 bit? I ask because, I have seen other motion machines that move fast, such as your machine struggle with 8 bit electronics, like what is standard in most control boards. This is especially noticeable on curves.
Not sure this applies here but…I ziptie mine prior to final tightening to ensure the belt teeth remain engaged.
