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ENDER 3 Belt tensioner

by MakeChetti Jul 2, 2018
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wont this deform with PLA overtime? cause the belts to loosen?

Hello, need support?

Those who are complaining about the screw with threads on which M5 bolt is fixed, snapping. Put it in the boiling water and turn off the gas, let it stay there till water reaches the room temepture. Print that screw part with 100% cubic pattern infill. Thank me later :)

  • Posted with 3D Geeks Thingiverse Browser App

hello! since many have printed at 100% and have no problems with the screw fitting, for those like me having problems and will need to upsize the nut, or some other type of scale, why wold be the problem and what could I test and calibrate to solve this problem?
I already test the flow with the cube test and i'm getting correct mesurement... it is not the flow... what else could be?

A couple of tips for those printing these. As Zerocorebeta has said print in the horizontal position. 4 Bottom layers, 4 top, and 4 perimeters. Print at max height for your nozzle and run the material hotter than you normally would. These two things increase layer adhesion, which is key to a high stress part like this one. PETG or ABS are better than PLA for this also.

All people who are having problem with it breaking are printing in wrong orientation. Print it horizontally, use supports and viola even at 15% infill, it doesn't break, no matter how tight you make it.

  • Posted with 3D Geeks Thingiverse Browser App

I unscrewed the original bearing, works like a charm with the tensioner (with spare M5x25 and M5 T-nut)

Just made one of these for the X axis but the screw part (one with the threads) split in half before even finishing the first print.

It broke clean off where the bolt goes through, on both sides. Luckily there was still enough belt tension so the ongoing print went fine.

Maybe I tightened it too much? I don't know.

0.4 nozzle 0.2 layer height 100% infill 200c nozzle temp with AMZ3D black PLA.

It will print fine without supports if your Esteps are calibrated (in fact supports suck on this because the threads are so hard to clean off)

Printing another one at 210c now let's see if I'll get any better adhesion...

Ok, I'm having the worst lock with this design. I printed the tension pulley at 100% infill, but they still broke either at where the screw tightens or off of the base. I don't believe it's overtightened, but I really think there is a flaw or it needs to be metal.

I'm having the same issue, see above. Maybe we should anneal / heat treat the parts before starting to use them.

Heat your oven to 60 degrees, convection fan on, heating element off, put the part in and wait an hour. Much like metal alloy heat treatment. The polymers in the plastic slowly start reflowing and they rearrange themselves in a much stronger way.

Google will show you how

One thing I’ve found out with making parts in pla is you can’t just use any old leftover pla to make them. Some colours and brands are just way too brittle (copper for one). If you’ve leftover pla+ it tends to work best. Since I use steel tips I tend to have to do them at 230° as well.

Just printed this out. This is probably obvious to most, but it wasn't to me and i felt pretty dumb. The bearing bushing needs to go in the bearing on the original tensioner. I ran it on a print without the original bearing before i realized that has to happen. I actually had to redesign the bearing bushing with a slightly larger inner diameter to get my m5 through. Otherwise its a great print, excited to see how it holds up and if it makes an improvement.

I have printed all the necessaries (in PLA), however I am reluctant to install this because I imagine bearing-bushing would very quickly wear away to nothing as the bed moves back and forth during prints. Has this been an issue for you?

Did not work for me. Printed 3 separate times and every time, the body would snap. Printed on an ender 3 with .16 layer height at 60mm/s.

Thread is not work. Any ideas how to print it? I used 0.12 layer high.

Screw it in tight then unscrew it then screw it in tighter and unscrew.. keep going until the threads loosen up, might take a couple of minutes.

I tried this method until I destroyed one part...

Hello, first of all, thanks for the design :)

I have a doubt, I printed all the pieces for X tensor and everything went well. I just put desarmed the original piece, took the bearing and put over the "bearing bushing". That was fine too, the problem is, once I tried to put this in the middle of the tensioner puller, I saw that the original bearing it's smaller than the gap inside the puller. I mean, you can see in the image. The bearing, together with the bearing bushin, are to small for puting inside the tensioner puller.

My printer is the ender 3, and I just bought it one week ago.


Btw, I didn't put the screew until I find a fix for this ;)

Edit: I almost forgot, There is a gap in the back part of the support, I don't know if it's there for any razon or by mistake. I added another photo.

I dont understand how people are making the nut, there are two lobs on the thread as shown in picture

There are non blobs in the files. The matter is your mesh software that don't read properly the Stl files. Many software do this, many time Blender too (not in this case as you can see in the photos attached), this because Stl files are non create to modify (even if many software can read it, but many times is oly possible to do some generic modifies as to Scale ecc.. but not structural) but for the slicer. Try to open direclty with you slicer (Cura in the photo), and all is working well,

Printed this in PLA originally. After about 1.5 months of being on the printer, the y axis tensioner delaminated in the middle of a print right where the bolt goes through. I am currently reprinting everything in PETG as it worked great before it broke so I am hoping it will hold up longer with being made out of PETG.

I am not able to fit this. I tried on the X gantry, but the hole does not line up no matter how much I pull the bearing towards the right. The X tension case is is flush against the X gantry in the slot and the tensioner is slotted in as far as it goes. This is on a standard Ender 3 (bought 2 months ago)

Has anyone ever tried these self-printed screws here? whether these are stable enough?

A Second Question..
I would like to buy optional Bearings... Witch Bearings Creality originaly uses for the Ender 3 Pro?
608z oder 688zz oder others?

Sorry a third Question too..
Can i use this for an Ender 3 Pro?

NUT JOB | Nut, Bolt, Washer and Threaded Rod Factory

Beautiful design. Thank you for sharing!

Everything came out great on first print. 50% Gyroid infill, Speed 50mm. Perfect fit, did not have to scale any parts. The nut threaded easily on the bolt right off the build plate. Feels sturdy, not sure how people are breaking these when putting them on. Hatchbox black PLA. I should have printed these a lot sooner as its way easier to dial in the belts.

If you don't have an M5 x 25 mm, you can (temporarily) use an Alan key as the axis for the bearing. It doesn't provide any clamping force on the tensioner assembly, but with enough tension in the belt it seems pretty stable.

Video is recorded in French but still a wonderful example of how to install this mod. Helped me a lot!


Vis sure is handy...one thing that is not entirely clear though.....do I really need to find 2 x m5 x 25mm screws and nuts....or can you use the one's you take off/ what is already there?

I'm so sorry for the noob question but I'm guessing I have to print two pullers and nuts correct?

Sorry, I answered my own question. Yes, two pullers, nuts and bearing part.

would it be possible to get the drawing file for this? I'd like to modify it a bit in fusion360 and I'm not skilled or patient enough to do it from the STL lol. thanks

better to switch support on to avoid printing it for the 4th time....2 down and now printing for the 3rd time

The original x tensioner positions the bearing a bit lower than center of the extrusion keeping the belt from rubbing on the v bearings. i noticed that with this one my belt rubs a bit so i shimmed the tensioner to angle it down and drop the bearing lower. i was wondering if anyone knows of a remix or if this could be changed to lower the bearing a bit. or maybe im just missing something

Hi I just wanted to say thanks for the great work, I printed this in standard PLA on 210 for better layer adhesion and so far it hasn't snapped neither it showed any signs of actually snapping :). This helped me a lot, especially with the X-axis which was not that easy to properly tighten, so once again thanks and keep up the good work! :)

Do I need the bearing/bushing or not? I'm confused

I tested 5 mods and for mi , this is the best one, as @naymo said, scale all nuts at 101,5 %. I think is missing two holes (on front side) to screw the tensioner at the X axis. Works fine for me with pla premium formfutura (vacuum bag opened 2 years ago), 205ºc, bed 60, infill 50 (and the ender 3 profile in cura (latest version), draft mod. Incredible quality for a stock printer. Good job !!!!

printed the x axis tensioner with the nut @ 101.5% scale and its dam near perfect, solid too. Its that good of a print i may not need to use it just at the moment on my printer.

I printed it out with PLA+ at 215, bed 70, 3 walls, 40% infill. I did have to sand the outside and file the inside of the bearing holder to allow the bearings to easily slide on and the center bolt to slide through. I was high hope of this print, however when tightening it to the proper tightness the center piece of the x belt tightener snapped. This may be due to the filament I used, may reprint in PETG.

What filament brand and color did you use in this picture?

What filament brand and color did you use in this picture?

Nut won't slice with Slic3r because it's full of errors. I hope the original nut will work...

So i tried printing this with my realtive new Ender 3. I have Problems with the Puller nut, it doesn't fit the tension pulle - too tight. Broke some of it while trying to screw this together. Fitting of the other parts seems ok as far as i can tell. Any idea what i could do? Simply make the nut ~1% or so bigger (scale up)?

Same here, extremely tight, can't get it on. It feel like the pitch of the threads are different. Fixed it by printing the nut at 103% scale.

For the Y tensioner case, do we need to have supports for them?

Hi, there i just installed the y tensioner for my ender 3 and it seems to work. The bushing was ultra ultra tight tho, so i just grinded it down a bit and used a drill to widen the inner diameter. now it fits very easily and tensioning worked very well. I hope it lasted.
I printed it with 0.1 mm layer height and 2mm shell diameter. it will be quite robust this way. Its a bit overkill i guess but wall number makes a big difference for stiffness.

The x tension installation was pretty tough, since everyting is pretty close to the aluminium rails. it finaly works but i dont recommend for that part, i had to remove some material with a rotary grinder to get everything in place.

Works in Ender 3 Pro?

No this does not, at least not with the version I got in the mail 12/13. The Y-axis bearings are smaller than the X-axis. Out of the box, they ride on an unthreaded portion of a M4 bolt. So no, the two M5 bolts called out will not work. Also, the Y-axis aluminum extrude is double wide and the print is for a single.

This is a good design in theory, but as you can see below people are having issues with it. In my personal opinion, hand tightening is a pretty good option to avoid wearing the belt too fast or deflecting the motor.

Any chance to have an Ender 3 version for the Y axes in the near future?

Comments deleted.

One tip I can share is do not try and put the threaded ring on without the threaded piece in the outer sleeve. When the threaded inserts are in the outer sleeves, they are supported much better and will have less chance of breaking while you try to screw on the ring left right a few times to get the threads worked in. also good idea to have the screws in with the bushings as well so the threaded tabs do not move too much.

Comments deleted.

Maybe an installation guide and needed parts list ? You assume everyone checked or used the remixed version of the design and just need to tweak stuff. I didnt know that I needed a bearing to install this thing. Printed and not doing anything with it. Please provide some information to your work. THank you!

You use the bearing off of your printer.

Comments deleted.

Nice work but very weak about 5 threads in ...snapped when putting together, printed in PETG

Mine usually break too.
I think I've been setting too low infill for that.

Well, im sorry your print snapped, mine never did, in PLA at least. What are your settings? maybe it snapped because the way you printed it, i never had one snap so I wouldnt say it is weak.

Can I use the screws from the standard Ender 3 assembly?

Mine came with some spare m5x25 screws which is what you need for this.

no, the stock ones are too big for this design.

i have a problem importing bearing_bushing in simplify3D....

Why not design it to utilize the original bearings and nuts/bolts? Bearings are going to be way less friction than having a piece of PLA/PETG/whatever rotating about the threads of a bolt.

I think if you take the time to actually look at the design you will find that it uses the stock bearings and the bolt is downsized for size and integrity purposes. but hey! you can always design your own or remix it if you don't find something already made that suits you ;)

It's not clear that this thing uses the stock bearings, considering that they are not mentioned in the description nor shown anywhere in the pictures. I actually printed the entire thing out already (multiple times...since the tolerances suck and the puller nut needs 102% in the X and Y), so I'd say that's a pretty good look at the design! You can always take better pictures next time to show how it all fits together ;)

feel free to design your own if you are not happy with the free design here. tolerances worked great for my printer settings, i cant vouch for everyone else's printer as they may all differ on calibration. but sure it is easier to complain so i understand. this is based on an very popular design: Quote "This is a remix of the well known belt tensioner from fooyabt that was accommodated to fit the X and Y axis for the new ENDER 3."
So common sense is to look at the original design, just as i had to do to remix this and put it all in one nice little package for ender 3 owners.

Look, just take better pictures of your design. It's not that hard and takes like 5 minutes. That's way more to the point than everybody independently having to go find the original design, diff it with your work, and figure out what you changed.

I see a lot of comments on here regarding problems with the thread tolerances. Your design may work well on your printer with your slicer configuration and filament, but a non-trivial number of people are having issues. Fair enough if you just want to tell them "works for me," but since so many people are going to be eating up print time and filament on this thing, you might want to look into it.

it keeps printing out too brittle

Hey, could you post your settings and pictures of the parts printed pls

that is 100% your printer settings, could you post them here and pictures of the parts please

had to re-print it, it broke after a few prints

After installing the tensioner on the Y-axis, the belt now rubs against one of the rails and drifts to one side or the other. Any tips or tricks on how to keep the belts from rubbing on the frame?

cant figure out how to get it on


It does require a bit of tinkering and fitting, would be hard to explain through words but I will try. Which part are you having difficulty with?

how do i get the screws in? if you could attach a video of assembling it with the belt, that would be great

The designer of this thing is not interested in documenting his design, so I don't think you'll be seeing better pictures, let alone a video.

So ungrateful! Not once have you ever said thanks for his time and effort. He doesn't owe us anything and what he does is for free using his own time. Please learn how to use Fusion 360 then create your own.

i'm new to 3d printing and don't know any other way to get my x belt tighter. i don't know how to put this on the printer

can't figure out the Y-axis bracket? I have a new version of the Ender 3 and the Y-Axis bar is a double wide/tall bar. Do you have another version?

Also the X-Axis bracket has a small lib on the inside face that causes the bracket to sit cock-eyed and makes the belt ride to one side (see pic) . Is it just my machine ?


On the X-axis, the 'lip' should fit on one of the sides. If it doesn't fit on one orientation, switch it around. It is supposed to fit on one side. Check out Hamud's photo. It fits really well on my Ender3 (September 2018 version). Not sure if there's any difference with Ender3 pro X-axis though.

Yours is the Ender 3 Pro, it has a 4040 profile instead of the 2020 which is in the standard version.

On my X-axis seems normal, see photo below.

Printed all parts for the X axis at 100%, aside from some spots on the surface that needed shaving, the fit of the tensioner on the extrusion and the nut on the threads was spot on.

Still have to get the screws to install it.

Thank you very much.

Edit: the bushing for the bearing has a diameter too large, had to scale it down to 7.90 in Y and X.

I dont get it, how is the X Tensioner attached to the Frame? The M5 Bolt is to hold the pulley correct? How do you mount this to the axis? T-Nuts?

When you tighten the belt the threaded part gets pulled outward while the tensioner body gets pushed against the extrusion. Thats how it stays in place.

I tried to print these. Came out mostly fine. Re-printed the nuts at 101 or 102% in X and Y so the thread better.

When I mounted the X-Tensioner and gave the belt some tension, the tensioner puller broke. Not sure if this is just due to printing at the wrong temperature or layer adhesion in general or because the filament is just not suitable for something like this. Recommendations are welcome.

Printed the X tensioner , but the nut turns only a few turn, then stops. :( The threads are looking ok. can you make a little bigger nut?

I printed the Y tensioner earlier and had to print the nut at 103% and tension puller at 99% to get perfect fit on my ender 3.

In the meantime I forced to turn nut left-right few times and now it seem to be working correctly.

Hello mate thanks for the amazing design. My question is, is it possible to make another version where the turning knob is bigger in diameter to get more grip when tighten the belt ?

I suppose you could, I don't how how good will it look, is not like you need a lot of force to get the right tension.

How about this mate, a tool to go over the knob to spin it easier, then you can remove that tool..since the knob has those groves so its easier to have another bigger and tighten just a tad.

X axis tensioner works well with Creality CR-10. Thanks.

Are the bearing and bolt supposed to be a tight fit? I had to use a plier and a ratchet wrench to screw the bolt into the bearing. I followed the instructions, printed the bearing (and all other parts) and bought M5 x 25 mm nut and bolt. Other than that, it works great. I had to take it out because it's messing up my prints.

It could vary by printer but mine was a tight fit but did not require tools, just bare hands. Regarding your prints being messed up, i couldnt tell you why, it didnt affect my prints once i set the tension

The ID of the bushing is a little tight (had to scrape and force 5mm bolt through back and forth) Not a big deal, but a drill bit will save some fiddling. X housing is a bit loose but tension holds it in place anyway. If I ever had to print these again I WOULD NOT USE BRIMS. had to carve and scrape that closest layer off! No fault of the design, just some advice for the next guy! Love the design and these things look sick and function well!

Comments deleted.

Is there a method for determining what the ideal belt tension is?

The tighter the better since this results in fewer tolerances causing more accurate print results.

Tighter is NEVER better. Over tightening the belt will result is excessive strain on the stepper motor, bearings and the belt itself. Stepper will have to work harder, draw more amps and run hotter, belt will stretch and wear out prematurely as will the bearings.

Tighten the belt and try to move the axis. Notice it takes more force the tighter the belt gets.

Guitar string tight is what I've heard recommended

For both tensioner mods I have to remove the original roller bearing and remount it on the bushing and thread it through with a new M5x25 right?

Yes, you shouldnt have to thread it through the bishing but yeah, thats the idea, you only reuse the bearings

Oh, so we reuse the original bearing? I placed the belt ON the printed bushing itself. No wonder why my Ender 3 wasn't printing that well. X_X

Thanks so much for this, a great design !

You are welcome

I printed these 0.2mm layer height, 20% infill, 3 line shell with PLA. Looked great! However, first print after installing, both tensioner pullers on X and Y broke on one side where the two arms split from the base. I printed them in the default orientation as depicted in the posted images. Anyone else have any issues?

I'm having the same issue. Printed with PETG and the arms snap off every time.

That is odd, i have printed dozens of these and not one broke, the ones i use now are 2 preimeters. Im thinking that it could be layer adhesion. Could you post pics of the broken parte?

I'll post some pics later this evening. I'll experiment with layer speed and printing temperature to see if I can get better layer bonding. Might not have my setting dialed in correctly for my filament.

It was actually worse than I thought. haha If it works fine for you it must be my print settings. I'll report back if I get it figured out.

omg, im sure that is not the file, that looks like there was not enough material on that layer to make good adhesion. give it another try and see what happens.

After printing off a bunch of these Print Temperature Calibration Spindles (https://www.thingiverse.com/thing:35088) I discovered I have been printing with a nozzle temperature 30°C cooler than the strongest print temperature I found experimentally for this particular filament.

Reprinted with this new temperature (and upped the infill for good measure) and it has went through two 3hr+ prints without issue.

Thanks for a reason to figure out how to get stronger prints ;)

Print Temperature Calibration Piece

I'm looking for a better way to adjust the belt tension on the ender 3, with this upgrade is there the possibility that with long prints that the tensioner may loosen and let the belt slack?

No, it will not loosen as the tension willl prevent any movement on the nut

Anybody having issues with the nut? Sli3er is reporting 1236 errors on the nut STL

I'm having issues with it as well. Slic3r won't work for it and Cura looks just horrible.

Didn't count the errors, however it seems they even prevent the model from showing up on the buildplate after slicing...

Just printed off the y axis tensioner. Works perfect, much better than the stock tensioner.

Can you provide some guidance on installation please?

im not sure exactly what you need to know. You will need to insert the bushing in the bearings then assemble the puller and housing using the required m5 bolt, the housing is designed to fit into the extrusion V slots.

That'll do it! Thanks!