Anet A6/A8 upgrade: Y-Belt tensioner

by Photograaf16, published

Anet A6/A8 upgrade: Y-Belt tensioner by Photograaf16 Dec 11, 2016

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UPDATE 31-12-2016: Some people had problems with the Frame_L and Frame_R so I have update these files. they are a little bit stronger now. If you have problems with the size, you can contact me and i will make a smaller version for it :D

I have made this upgrade for my Anet Anet A6 and A8 3D printers to get the X-Belt to make it easy tighten it up.

Two friends of my asked me to make one and I wanted to make one myself so that's why I created this tensioner.

You will need to use this tensioner all parts 1 time(Frame_L and Frame_R are the same!). Also, you will need in total 5 M3 screws and bolts(1x ~30mm and 4x ~10mm).

A great youtuber maked a video about this model:

Please feel free If you like this model and you want to support my work that I am making, you can donate me if you want with paypal: https://www.paypal.me/JordanHogetoorn

Print Settings


Anet A6


Doesn't Matter


Doesn't Matter





How I Designed This

I designed it in Fusion360, I first measured all dimensions and begin to draw it on the PC with Fusion360.

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Does this work for the newest version of the Anet A8? Ordered in August/September.

Ii have some issues, when i tight the belts, pulley goes down a little and whole mounting is not stiff, i can move it almost in any directions, that causing some problem with proper belt alignement and what is more important when i tight it more it is more hard to move the heated bed, after loosen belt bead move smoothly. I was hoping that it will be more smooth than rough after installing this upgrade, what to do ? please help :(

Aug 19, 2017 - Modified Aug 19, 2017

thank's very much ! perfect for my anet a8
make in 0.15 with 20% infill

x belt and y belt upgrade with a FFF Improved for my printer, gives a great result .... no grooving on printing: perfect!

Anet A8 2017 frame?

Aug 21, 2017 - Modified Aug 21, 2017
benoit12 - in reply to chaos_jockey

Yes, it sails slightly the front face when the strap is stretched ! But it holds ... maybe I have to print a front face in case it breaks?


Aug 13, 2017 - Modified Aug 13, 2017

Hi, I printed the new versions, but they don't fit my anet a8, I had to sand them quite a bit down, and now it's still a tight fit.

Any solutions to this already?

The screw works like a charm by the way. Great design!

I printed the newer version but the screw and the back plate don't fit. The screw seems larger in diameter than the back plate. Any suggestions?

I got 88% to work guessing at it but i'd try 89% if I made a new one

Works perfectly on my anet a6

I printed the newer v2 level of this tensioner and it fitted and worked like a charm on my freshly build Anet a6 acryllic printer. Thanks.

I have printed this but im not sure it my a6 or the stl file, cos the bolt and back plate the thread wasnt even round

How can that fit into the back plate?

Comments deleted.

Great design, however i did have to file the parts that go into the squares on the front acrylic piece. It could've been my printer that printed it weird.

Hey there! I'm trying to get this to print correctly, but I'm having problems. The screw will go into the plate initially, but when the bottom of the screw reaches the bottom of the plate, it will not turn any further. I tried increasing the layer height to 0.06mm, but I'm still having issues getting them to fit. I'm trying to use fine grit sand paper to get them to fit, but it isn't working too well. Any thoughts?


Also I printed mine on an anet A8 with duel mosfets, inductive prox leveling and ABS. Temps were 250 and 90. First layer thickness was .3. Used Aussie Instant Freeze hairspray as an adhesive on top of Duck Clean Release blue painters tape.

Worked great for me. Took a file to clean the ends up. Took like 10 seconds, Also had to change the orientation on the slicer so the widest was starting on the bed. So basically flip everything 90 degrees. I printed everything in one print. Awesome job!!

This does not work with a 2017 acrylic frame. The thingy frame arms are too thick & far apart. Filing them down weakens them to the point where they break under tension. Resizing frames does not work.

But I used these instead: https://www.thingiverse.com/thing:2051259 and rezized the bolt and plate from this thingy to 90% and 91% respectively (drill out screw holes to fit)

Anet A6 New 2017 Y-Belt tensioner holder resized

Ah nice, thanks!

Just to clarify, Bolt resized to 90% and the plate resized to 91%?

Thanks for this!

May 22, 2017 - Modified May 22, 2017

I made a complimentary piece of hardware that works perfectly with this tensioner. It's a frame brace that locks the back and front cross braces from curling in. It's made with threaded rod. Best of all you don't have to secure the printer down to a table for it to work. Check out the YouTube video. https://youtu.be/KgpeB1dEOTA

Tried this in PLA, ABS and PETG and every time it's too tight. Both PETG and ABS snapped the thin points where the nuts go just trying to insert it into the A8 frame. PLA snapped them when I tried to tighten the big "bolt" to tension the belt. I think a solid design with smaller holes on the top of the 4 posts would work better so I can just thread a screw into the PETG without the nut.

The tolerances were way too tight on this. Took some real elbow grease to get the screw wound into the back plate and I had to go over the four posts with a dremel to get them to fit the front plate holes. Best to drag this into a CAD program and adjust to your machine's measurements. Not something for someone to just print up and expect to fit. You're going to need to either adjust the model before printing or file down the printed part (not an acceptable option if you want a part that works smoothly).
Other than the poor fit, it does work well once it's been adjusted and a great mod for the A8.

Hi Photograaf16 - I'll take you up on your offer for a smaller version. Mine printed out about 1mm too large on the Z axis of the four posts but should be no more than 7mm and I'd err on the side of caution and go 6.8mm. In fact, would you mind much if we mod the design just a touch? Instead of using a captive nut I'd prefer to tap the screw into the plastic and do away with the nut. It avoids what could be a weak spot where the nut sits, especially with the narrower bit around the nut. Tapping 12mm should more than compensate for the absence of the nut.

The rest of the design is brilliant and printed out nicely. I need to break-in the tension bolt a bit but that's normal for a printed nut and bolt and I had the same with the printed wingnuts I'm using on my stock spool holder.

Now I have to put my Y idler back together so I can print the new part. It's part of the fun.

Does this work with the "newer" Version of the a8?

When looking other y-tighteners, some people say its not working with the newest version because of the belt toouching The frame or something...

Does anybody have experience with this?

Hi Anox - I've just printed mine and while I can't say it will work, I've lined it up and it looks like it shouldn't rub on the underside of the hotbed. Comparing the printed version and the Perspex version, the idler wheel is just about at the same position on the Z axis. Photograaf16 did a good job on this design (although per my post and like so many others, I'm struggling to get the idler brackets to fit through the Perspex).

If I get bored this evening I'll reveng the idler brackets in OpenSCAD and post my code (after testing).

Well, I printed out a replacement for the idler bracket and installed the tensioner. It works great but I'm somewhat disappointed because it's tipped because of the tension, even though the idler bracket is a reasonably tight fit. It would be really easy to over-tighten and break the Perspex so a measure of caution is due. I've ran a test print but it looks like I've damaged my controller board. Maybe too much radial stress on the Y axis fried a MOSFET? I'll troubleshoot later today.

Working on my Anet A6. But it was very tight, had to file off a lot :)
Still great upgrade! Thank you for sharing Photograaf16!

My advice? Dont print this in ABS... I found out the hard way :( The shafts that go through the front of the frame are way too tight so had to sand them down, but were still tight. Then ended up snapping every stress point cos of ABS being too weak for any sort of pressure...

Cool design though so may reprint in PLA

doesn't work in PLA either. it was still too tight and I had to sand down a little. I also tried it in PETG and still too tight. Every time the thin parts where the nuts go snap.

I just can't get it to work!
The thin part where the nut comes always breaks under tension. Already printed this part 6 times but on all tries it broke trying to insert it into the frame or when this went good, when there was pressure of the belt... does not work because it is too tiny.
Printed with PLA at 0.2mm

Just made one with my Anet A8, the screw threaded into the plate perfectly (very tight fit but does not bind). The L and R brackets needed to be filed down quite a bit for them to fit, and I also filed the holes in the frame just a tiny bit, but it wasn't that much work and now it's a perfect fit. I would say use thick walls for the brackets, but it doesn't really matter since the nut has to fit, limiting the thickness anyway. I haven't actually done any calibration boxes with my printer yet.

Amazing! tight fit but a little persuasion made it work! Thanks!

It was a super tight fit for me but I was able to get it to go eventually and now it works great.

The thread of the screw is too wide or the thread-hole is too small. Basically, I was able to screw the screw into the thread, but only with a pipe pliers. :D

Possible that there is no problem with PLA, but I print with PETG and there is no big heat distortion. So I have printed the screw with a scale of 98% in cura, now it fits perfectly.

could be that you have binding in the x or y axes. use calipers or something to measure the dimension of your print to see if you have an issue

Same issue with PLA - haven't tried scaling it down, I busted out a craft knife and whittled the thread-hole a bit.

Cant seem to get v2 to print. Walls by nut inserts keep snapping on install. Printed in all directions. Still no success

Printed perfect and no work required. My zonestar p802 has stripped throat threads(extruder actually moves around a bit) and I have to push down on bed in certain spots to get that first layer down but it's calibrated - so I agree with the calibration suggestions.

Be carefull this works to good. I have overthigten my belt. :(
My recomendation print a calibration cube before and and after installing this.

I like this design. But have you ever thought about adding a pulley on the bearings? I have tried this one: http://www.thingiverse.com/thing:2099608 but the space for the bearings is a tiny bit too small.

Idler pulley with tooth for Anet a2 (a6,a8)

the hole in the back plate is too small. how might i correct this?

For folks who are concerned about their calibration. I too am new to 3D printing so I made my wall thickness more than usual, 1.6mm. This allowed me to do a little sanding when i was done and that helped it so that it slides just perfect. I am still trying to get better with calibration as I hope others are as well, but this is a good little cheat to help along the way. Great design Photograaf16, thank you for sharing.

Mar 9, 2017 - Modified Mar 9, 2017

hey man do i need to print that bolt a certian way?? shoult i print them exactly the way the extract in to cura? sorry im brand new to this 3d printing

Originally I printed it as extracted, on it's side. The supports inserted by cura stuck to the threads and caused problems. It could have been cleaned up but it was so much simpler to print a new one with the bolt head oriented toward the bed. I have to say that I'm impressed. It works very smoothly.

Mar 7, 2017 - Modified Mar 7, 2017

This is one of the best upgrades for my Anet A8, so much difference in the belt tension and really easy to adjust, I printed in Matchbox orange PETG, very good looking and functional, the only thing that I do was sand it a little and they fit perfectly fine, great design Thanks!

Printer Setting Matchbox Orange PETG S3D:
0.2 mm layer height
35% infill
240 Hot End
60 Bed
3 layers for top and button
40 mm/s velocity
No support or brim required

I wanted to post a comment here because of the discussion of a lot of people having issues with the bolt fitting or the legs fitting. I had what I thought was a great quality print, but it wasnt. It wasnt calibrated. I had prints where the 20mm cube would read 20.2 or larger. However, I calibrated my extruder; set the correct number of steps in firmware and measured my filament over the span of about 1m (10 measurements, then average) That made all the difference. Z is now at 20.00. X 20.03 Y 20.02. Just from extruder calibration nothing about adjusting xy steps at all. Once I had that and reprinted, it was like a different material was used. It looked different and everything went together very smoothly.

For those arguing that the part is too big, Please validate how you're able to make that claim. If your extruder is not calibrated and your slicer doesnt know the correct amount of plastic in the extruder, then it may over or under extrude. Over extrusion leads to squishing which will lead to an unusably enlarged part. So, please validate how you are able to make the claim that the part is too big. Did you measure the part in a CAD program vs what you have measured on your printer? Or are you basing the measurements off of the printed part, which may or may not be dimensionally accurate due to calibration issues?

THANKS! i am happy to hear that someone see what i mean! Thanks :D

No problem. As a n00b myself, I thought I was getting good prints and good print quality. But when I printed this part out it wouldnt fit together. I sanded, cut, and all that but it just wouldnt fit. Then I saw some of Tom's videos about calibration and how important it is. I got things setup to calibrate accurately as I could and it was a night and day difference. After I was calibrated and reprinted, everything went together rather nicely. The legs are perfect, the plate and bolt fit nicely. Sometimes you're lucky and get good prints out of the box. Other times you wont. You'll also need to calibrate often; filament is not consistent in size and when you're talking about a .1mm difference in size; it really does make a difference.

Yes, Please share the link to "Tom's videos" :)
That would be awesome!

Hi, can you share the calibration video? I am very interested to learn about it. Thanks

I think he's talking about this guy;
I'm going to check it out now, I see he has at least 2 calibration videos :)

i just printed this, but the thing is, the "legs" are a bit too far apart for the square holes in the acrylic frame :/ the parts fit perfectly between them, but they dont fit in my A8. could this be an issue of scale? (i didnt scale it) my settings are 195/55 PLA .2mm layer height, .4mm nozzle
Thanks in advance.

Feb 5, 2017 - Modified Feb 5, 2017

Could you tell me which is the difference between the nominal diameter of the hole and the diameter of the shaft (Dh-ds) when you designed it? I think it is known as Clearance. It would be very useful to know it, because the screw fits perfect for me. Thank you!

whats the part name? then i can look for you :D

Sorry, I was meaning the nominal diameter of the screw hole from the part named ‘Back_Plate’ and the nominal diameter of the screw named ‘Adjustment_Screw’. I guess that to fit properly the diameter of the screw is smaller than the hole.

The are the same size but with a small clearance, Fusion 360 has a fuction called "Thread" and I use that function to make this screw and plate. the clearance is 0.464mm and that should be perfect strong. yes you have to have some power to get it trought it for the first time but this should be good.

here is a picture for the people dont believe me that it has clearens:

Perfect, that's what I was looking for! Thanks! ;D

Why this happens - https://postimg.org/image/9jigj9gup/ ? I print 2 parts (Frame_L & Frame_R) normally, but when i print bolt it do this.

What are your setting? PLA/ABS?

it should be printing without any problems... i could only help you when you post your setting.
If you use the settings that are in the print settings section it will print nice and good.

hmm, the bolt threaded perfectly but the legs were a little too far apart and when i pushed them in it cracked the acrylic frame.

If you use a Front brace like i made also this dont happend. i am sorry to say that but so far i know you the only one that goes this wrong.

i took the acrylic plate off to make sure it worked first oops but its my fault i should been more careful. I originally thought it was just the square leg being a tight fit i was thinking that in order for the part to function it needs to be able to slide through all the way so i forced it. Looking at it after i can see that the legs are about a mm too wide above and below both holes so the further i forced it through the more stress it put on the acrylic. Luckily the crack was was fixable, actually it was a small chunk of acrylic that snapped off one of the bottom holes, glue seems to be holding and the front brace supports it.

Since no one else has this problem I'm not sure whats wrong maybe my printer is printing objects larger then there supposed to be or maybe my frame holes are closer, I've heard theirs been minor changes like that to these printers over time and i just got mine a couple weeks ago. Anyways i like the design enough that i plan to measure and resize to fit my printer but before i do that i'm curious if maybe this is actually whats intended? and my problem is that i forced it too far, further then it should need to go in order to tighten the belt? That would make sense it does ensure a tight sturdy fit so there's no movement of the parts but i'm not sure it could really go much further then where yours is though without being at risk.

I have the same problem. It is too big to fit so I started sanding the print as well as the acrylic. Slowly it seems to work but I am not happy with it.

Why? if your printer is good calibrated then you should not have any problems. hope you liked it after you have sand it :D

The problem is that my printer is already calibrated as far as I could get it^^ (The sides of a 20 mm calibration cube are now ~ 20,3 mm wide, which is as good as I could get it). This small difference shouldn´t effect the fit of the parts.

I just printed the V2 and they fit the holes left to right, but won't fit otherwise. I think the legs are too far apart, and maybe they are too wide also.

PEOPLE, CALIBRATE YOUR PRINTERS. sorry i say that but why the most of the people that print this dont have any problems.

Feb 4, 2017 - Modified Feb 4, 2017
Lono - in reply to Photograaf16

its not a calibration issue, the part is too big. I measured the part with calipers and my print is accurate but i also measured the holes and the part is about half a mm too big on both sides. The legs on this part from top to bottom are sized at 28mm the size of the holes are 27.25mm. Originally i was sanding it to make it fit but the further i pushed it into the holes the more stress it put on the acrylic plate until it cracked.

I resized the part based on my measurements but i haven't tested it yet, If it fits correctly ill upload a remix.

Oke, but why this not happend with a lot of other people?

well that's what threw me off originally and why i wasn't more careful about fitting it.

I think its either one of two things. even though its a little too big there's some flex and i was able to push it through the holes about 25% of the way without too much issue. So I'm guessing people are able to get there belts tight without needed to go past 25%. In the picture you uploaded that looks about as far as i was able to go before it got too tight. I also looked at other files and in one of the remix's of this design they even recommend printing it at 98% scale because of the tight fit.

Or maybe there's some variance to the acrylic plates, maybe your plate holes are at 28mm. i got my printer recently so it could be that newer ones have slightly smaller holes.

I'm in the same boat as you. Upload that remix, please!

Looks like he changed it so no remix's are allowed...I've never really uploaded anything yet so i'm not sure how it works but I don't really want to brake the rules.

Worked great for me, bolt threaded right in with no filing or size adjustment needed. Thank you!

Jan 21, 2017 - Modified Jan 21, 2017

The screw was very difficult is not good size
This part is better size for me http://www.thingiverse.com/thing:2051259

Anet A6 New 2017 Y-Belt tensioner holder resized

I just finished and installed it. The screw does need to be slightly reduced in size. I took a flat file to mine and made it work though.

I had the same issue than Rob2, screw was a bit difficult to tight, my solution is to use soap and force step by step.
Now it works well.
I agree the better solution would be to reduce at 97% but I unfortunalty I didn't ready this post before printing

Just thought I should share my experience.

When I printed the bolt it was too big and wouldn't thread through. So I re-printed it at 97% scale and now it fits perfectly.

It might just be me but in case anyone else has the same problem, try 97% ;)

Have you calibrate your printer? Many of us dont have a problem with printing this. :D

is a frame brace necessary before i install this?

I think you don't need one but i really recommend to use one. i made some:

Anet A8: http://www.thingiverse.com/thing:1994168
Anet A6: http://www.thingiverse.com/thing:1919213

Anet A8 upgrade: Front&Back Stabilizer-Bracket's
Anet A6 upgrade: Front&Back Stabilizer-Bracket's

Nice design! I really like the printable tensioning screw.

However, I had some trouble with the nut attachments. They seem very hard to print and very brittle, so they easily break when trying to tension the belt properly. I'm going to keep using http://www.thingiverse.com/thing:1492411 for now, and maybe I'll try to print this again or make a remix without the 4 extra screws when I have time.

Belt tensioning modification for Anet A8
by Simhopp

I have update this :D check Frame_L V2.stl and Frame_R V2.stl

Thanks, these look much more rigid! I've just finished printing http://www.thingiverse.com/thing:2006595 however, which is really similar to your improved holder, so I'll try that first (don't have the right screws at the moment, though, so it'll take a while).

Anet A6/A8 upgrade: Y-Belt tensioner improved holder

Isn't this for the Y-belt? It looks like it is for the bed.

You're right. I will change it. Thanks