Belt tensioning modification for Anet A8

by Simhopp, published

Belt tensioning modification for Anet A8 by Simhopp Apr 14, 2016
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Belt tensioning modification for Anet A8, hesine, senhai, omni, m505 3d printer.

WARNING!!! this will stretch the belts! you need to upgrade them to fiberglass reinforced belt.
stretched belt will cause your print to be bigger in dimensions.

use M4 hex head screws and nuts for tensioning knobs.
which is readily available at Home Depot or Lowes.
25mm length bolt for y axis, 50mm for x axis.

x utilize thumb nut, y utilize thumb screw.

two M3 allen head bolts are to put the pressure on x axis rods, rather than on the z carriage which will put force on the z axis rods. adjust it so that there would be about 1mm gap between z carriage and the bridge part.

you may want to install my frame braces before putting too much tension on y belt,
or the acrylic frame can crack from pressure.


for x belt, the photo shows anti z wobble modification, but it is not needed for belt tensioning.

and I would also recommend replacing belt attachment parts with my design
the toothed ones are very easy to use.
don't know about the looped ones, haven't tried.

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Is that the Printer you're using? :-)
Looking good!

Many thanks in advance.
But my experience is that to me the tensor of the Y axis has gone very well.
But the tensioner of the X axis, what it does is to separate the two verticals to tension the belt. And this does not seem right to me. So I reassemble the original.
All the designs I see on the internet use this technique and for me that is a mistake, because you are bending the rods.

Perón for the bad translation from Spanish to English of google translator.

Muchas gracas ante todo.
Pero mi experiencia es que a mi el tensor del eje Y me ha ido muy bien.
Pero el tensor del eje X, lo que hace es separar las dos verticales para tensar la correa. Y esto no me parece adecuado. Por lo que he vuelto a montar el original.
todos los diseños que veo en internet utilizan esta técnica y para mi que es un error, porque estás doblando las varillas.

perón por la mala traducción del español al inglés de google traductor.

well design but unfortunately it dosen't work with the newer design of the Anet A8. The belt i slightly higher than the older versions due to that the belt is touching the frame at that bottom and makes it useless for me. But thanks anyway.

good work my friend. works like a charm

Printed works good Thank you

At least for the newer A8 models the Y-tensioning is too low. It wont be horizontal anymore and the y-belt will touch the frame of the printer.

Comments deleted.

Does the z wobble just sit directly under the motor mount and idler? Planning on installing them with your printed x motor mount and idler.

The stock pulley holder on mine curves up, does this make the pulley lower than it used to be or is my printer a little different than yours? Wouldn't this make the belt not level anymore?

I designed it to be as simple as possible, and it is not perfect.
but the original parts are not perfect either.

the important thing is that it works, and is good enough.

I had accidentally ordered Steel Reinforced belts, so I ordered Fiberglass Reinforced belts...would both work?
And I'm not quite sure how the tensioner would work.
And, I'd basically take everything that's in the original X-Axis mount and put it in the X axis tensioner? Looks like some bearings etc.

I'm printing these now and will print the belt attachment part, then the Y-axis holder.

Turns out there were supports printed that kind of threw me off with connecting the X axis parts together. I removed the supports and everything fit together in each other. I'm still printing the belt holders (decided to print 4 of them to see which worked for me) so I haven't attached them to my Anet Yet, but I still haven't gotten the new belts, so I probably won't until I get those.

Why would you buy another set of steel reinforced belts.
I don't think this is explicitly mentioned in the manual but the Anet A8 comes with STEEL REINFORCED BELTS already. (at least mine did)

I'm writing this here in Caps in hope that other people who are thinking about saving a few bucks don't make this mistake.

problem with steel reinforced belt is, that if you put significant tension on it,
the steel wires inside will break after few hours of work.

you would not know that right away, because the rubber part will not break, but you will see the stretched area where the steel wires have snapped.

Demasiado grande. No entra por los orificios del chasis.

Did you also changed your frame? I measured your belt tightener for the y-axis and it is 5 mm lower compared to the Y-axis motor shaft. This means that the belt isn´t horizontal anymore.

On the y tensioner what is that screw called

sorry didn't read the description

You mention replacing the belt with a reinforced belt. Where do you get this reinforced belt?

ebay or aliexpress

Hi do you have the stl file for the left hand z axis part. I printed this tentioner mod and the parts came out great. Way better than stock. Now I want to print the left one to colour match.

Wich Anti Wobble mod did you use?

Front/Back X Rod conversion for Anet A8 printer
by Simhopp

Could you please post the parts of the x idler tension system separately. I can't figure out how to print the individual sections.

Whats the yellow part under the x idler in your photo?
it has the metal lead screw socket (not sure what its called) attached to it instead of the x idler itself.

it's "anti z-wobble device"

isolates leadscrew from steel rod.

so that any x y movement of leadscrew becomes irrelevant.

ok... thanks for sharing ur designs btw.

I've printed this piece and really look forward to utilizing this upgrade to it's full potential but I still have the original belts that came with the machine. Would you happen to know what type of belts (i.e. style/size) came with the printer unit or a suggested link for purchasing the new steel reinforced ones?

Thank you very much for your time.

gt2 or 2gt and 6mm wide.

gt2 or 2gt means teeth are 2mm apart.

and steel reinforced belts are white in color.

Thanks a lot for your quick reply and many contributions!


Than you very much for your posts.

I have downloaded this one. Would you please be so kind and share the the material and the print parameters.


well, pla should work fine, and 30% infill should be enough, 1.2mm shell thickness should be adequate.

Thank you

Btw do have and suggestion regarding filament guide ?


Check out my thing based on your model, worked out fine with little effort. Thank's.

Robert KB3LNN

My Custom Prusa I3 - Inner Front Panel Support + 200 X 300 Bed
by kb3lnn
Comments deleted.

Sorry did I miss something? do not see any file for the front brace.

Robert KB3LNN

check the link in the description.

Thank you very much I am sure I can manage. I use Design Spark Mechanical.
I was blown away when I watched this short 9 min. video on it. This is the best and easy to learn CAD ever. Please watch this short video on the subject. Thank's for your time.
Have a great day!
Robert KB3LNN
Video for Design Spark Mechanical

well, sometimes it's easier to just build a new mesh from ground up, rather than trying to modify someone else's model.

so, if your printer is not identical to the one shown in the photo, it would give you less headache to create your own mesh.

In the first photo I see a black front brace , I was wondering if you had a STL file for that. I had got a printer frame kit and it is set up close to yours. Thank's and Have a good day.

Robert KB3LNN

yes, however, there are several printers with acrylic frame that looks similar to Anet, but not quite the same.

you will have to make extensive modification in such case. sketchup files are also provided.