Anet A8 Improved Y-belt Tensioner

by freemark Jul 22, 2016
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This is the one. There are many Y belt tensioner which use the 4 square holes of the front plate. It doesnot work properly because the screw is not in line with the pullies.
This one is design to have everything in line: pulley, tension screws and belt attachment. It is mechanicly perfect and improves greatly the prints.
I use it with the belt attachment 1433295 thickness 10 mm.

This is the best upgrade ever! I was struggling to find the reason for my poor quality prints. I tried calibrating my printer several times with zero improvement in my prints. But then I noticed the y belt was loose so I decided to install this tensioner to easily adjust the belt and see what would happen. For my surprise my prints now became perfect! Thank you so much for posting it! See the before and after:

Wow, that's a pretty big difference. I'm glad it worked for you.

Is it possible to add a CAD file to the files? I would like to make an topological optimised y tensioner from this one.

It was designed in Tinkercad, they don't provide CAD files to export.

Do you happen to have the dimensions of the tensioner?

There's no way to extract a dimensional drawing in Tinkercad, so your best bet would be to print one and take whatever measurements you need.

Great design but the indent for the nuts are slightly too big. So when you try and tension the nut just spins round.

Thank you for this thing! Thumbs up to you!

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This thing is working perfectly to provide adequate tension! Making a big difference. Thank you! Using the screw pad you referenced too!

rather easy to print and finally I have a tight y-belt!
But I did exchange the heat-bed holder to a more stable one and unfortunately this tensioner is too high and blocks travel now :(
so this is just an intermediate step for me to help print one of the more complex prints which will use all 4 holes in the acrylic front.

Yeah, I just left my review. I love this tensioner, but my upgraded Y carriage just came in the mail and it looks like I'm in the same boat as you. This one is going to interfere with Y axis travel now. :( Time to find a different tensioner. Which one did you end up using to work with new new Y carriage?

this is great ! thank you

I LOVE this model, and really need it as I think my stock Anet A8 Y front idler is slightly "off" so the belt rubs the edge of the idler.

It printed quite unsuccessfully. I decided it might be due to the excessive shrink-curling of cheap ($12/KG on sale) filament, so reprinted it with good HatchBox black.

It printed perfectly!

The kind reply from Freemark was when I'd only shown the failed red one and was trying to figure why.

I can't explain how that happened, but you may be right about the different PLA's. You might want to try this remix, where they added supports between the upright pieces: https://www.thingiverse.com/thing:2812604

Y Tensioner Belt Anet A8 (alone)
by P3DAlex

I found the tensioner to be a great addition. I have a request though for a modification if you would please as I do not have the knowledge yet to make my own or modify others work. I bought new toothed pulleys and the new idler is too large for the detent you made on the original. WOuld you be so kind as to enlarge the area to fit a 188 mm diameter pulley with a 5 mm axle? Thank you so very much!

I might work on this at some point, but it's very difficult to accurately redesign something based only on a text description. You might try looking through the remixes to see if someone has done it already.


Thank you so much for sharing your design, helped big-time for this fresh noob in the world of 3DE Printing with my first 3D Printer !

i couldnt print any circular shapes without this and your X-belt tensioner too !

i am very grateful, keep up the most-excellent work !!

You're welcome, I'm glad they worked for you

the print quality is terrible but its helped in such a MASSIVE way that its enabled me to print a higher quality version lol

i used a cut-piece of an old credit/debit-card to prevent the acrylic from getting scratched by the screws :)

once again, well done my good Sir & thanks you so much :))


Will a 16 teeth GT2 pulley fit in this design?

Thanks a lot!

I'll answer my own question with a yes!

Just printed it and the GT2 pulley slides right in!

Thank you for uploading your wonderful design. I would like it print it but on the first try my printer knocked down one of the pillar at 80% completion. So now I'm wondering if you could upload the 2 pieces separately as I already have the flat screw plate and would not like to print it again. Thanks!!

To late, but i did a remix.


Y Tensioner Belt Anet A8 (alone)
by P3DAlex

Thank you for posting this essential. Not an easy belt to draw hand tight and better!! I have certainly taken probably a record 8 hrs so far to get this to remain in the vertical mode. For some reason I forgot to insert the Brim within Cura. Sure you guys can have a laugh, I am new. But the small legs that make the "U" get knocked over as the radius structure joins up. So disappointing. I am sure I have more and bigger to come, but I am trying to get the upgrades done and iron out the deficiencies of the Anet A8 and keep it busy.
I really ought to connect an hour meter to this thing as it is going to circle the globe so-to-speak :-)

Did it come out ok with the brim?

works as designed,

Thank you for making and sharing.

Beautiful part, printed perfectly the first try (even with my crappy X tension issues) and worked exactly as intended and my bed moves much more smoothly now.

in what orientation did you print this, is there a way to reduce support material used?

I printed it upright just as it's shown in the stl file image above. Supports are not necessary, just use a brim large enough to encompass the entire larger piece.

Cheers Mate :)

Resolution and infill?

Res .2mm and 25% infill should work fine.

so does this let you adjust the tightness or is it just the stock one with a different shape?

It's purpose is to adjust the belt tension.

Hi, did you loose any travel with this ??

Thank you for the info..

Comments deleted.

What bolts and screws did you personally use in this project?

Two M4 x 18mm, each with 2 nuts. The pulley was mounted with the original screw that came with the printer.