X Belt on a TAZ

Brand new unit. The belt continues to slip off the non drive end. How can I adjust this?


mine did the same thing a few times.

I ended up loosening the x motor, and sliding it all the way up…still happened, so i loosened up the set screws for the drive pulley and slid it towards the motor as far as I could, it has stayed on since, but I was contemplating flipping it around to keep the belt pushed over even more.

I also messed with the belt tension some by re-clamping on the smooth rods (they dud not seem straight). If it is too tight, the bearing mount will flex and the belt can slip off.

Well, having a new printer that basically was functioning correctly… I did the cheesy thing… I loosened the nut on the back of the bolt the holds the bearings that are on the non-drive side of the belt. I loosened the bolt about 3 turns and because I didn’t have enough clearance to pull the bolt without major disassembly, I took a flat washer and cut it the about 3/4 moon, enough that I could slide it on the bolt between the printed part and the other washer. I made sure the split was on the side opposite the motor so that any torque would cause the bolt to pull into the belt tension. Put it all back together and now the belt is riding exactly in the middle of both bearings. Half on one, half on the other… For now at lease, we’ll call this a fix.


Thanks all,

thought about doing the same thing

Sorry it took me awhile to respond to this. I saw it, thought up a decent response, and …oh look a bunny!

As of right now there is no “easy” fix to the belt sliding off. We have started checking every printer that goes out the door to make sure the belt does stay on, but that does not fix things for you. Really the only way to get the belts to stay on is to trial and error tweaking. Now this will take time and some skill, if you are not sure how to do it or you are confused, please let us know we are here to help.

    1. Make sure the printer is off and unplugged.
  1. After each tweak, slowly move the x carriage back and forth to see if things are better or worse.
  2. Things that you can change to try and get the belt to stay on
  • a) small pulley position on the x motor shaft. However be mindful that if the pulley is too far down it will make the belt rub on the belt clamp screw on the back of the x carriage.

b)Loosing or tightening the belt slightly. If you over tighten the belt you can “bend” some parts and they will crack. Now they will most likely still be functional, but you want to avoid the hassle of having to try and replace those parts.

c). Changing the clamp position of the belts. Sometimes loosening the clamps and moving the belts around a bit and trying clamping at slight angles will get the belt to stay on.
4. Advanced steps. These can require a fair amount of disassembly and while the belt might stay on afterwards it can sometimes mess up the calibration of the machine which can take a lot of work to get back to being good.

  • a) As aadamson suggested you can try adding shims/washers between the bearings and plastic x-idler so that the bearing are further out. The max is around 3 washers. The hard part for this method is that the z nut spring is a bit in the way and it is hard to undo the bolt to get the washers on. So if you still have your shipping clamps around you can put them on the z smooth rods to keep everything level. Then carefully you can remove the screw holding the z nut spring on that is blocking the bolt . You should be able to easily get access to the bearing bolt so you can experiment. If your clamps were tight when you put the z nut spring back on, it “should” not mess up your z height calibration.

b) You can try tightening the bearing bolt. If it is loose it might be angled slightly allowing the belt to slip off. However like adding shims the bearing bolt is not easy to access and it still might require taking off the z nut spring to get it tighter.

c) You could try losing the bolt and shiming only one side of the bolt so it is angled the other way. This one I have not tested yet in theory it should work however I am not sure how long it would last and if the shim would pop out after a few prints.

d)The way the belts are manufactured/cut they might have a curve to them so you could try flipping the belt around and seeing if that helps.

As you can see it none of this is “easy” we are looking into maybe changing parts, but we don’t have anything that would be simple to replace that would fix all problems… yet. We will let you know when we do find something. Hopefully you can get it working in the mean time be tweaking somethings so you can get to printing.