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Anet A8 Improved X-belt Tensioner

by freemark Jul 22, 2016
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Hi, M4 nuts are to big and M3 just spin round in the hex hole am I doing something wrong here ?

Look at the readme.txt file where all is explained.

This tensioner causes my x-axis to get stuck at some point. It may not bind the z-axis, but it may bind the x-axis due to the offset weight of the extruder motor.

I'm not sure exactly what you're trying to describe, but the only way I can imagine the tensioner binding the x-axis is if you tightened the belt too much.

that two bolts are M4 x 40? Thanks

I used M4 x 30, but you could go longer if you want

Printing another after 1 year as it has sagged in the middle. PLA. Good tensioner.

Thanks. You might not have had enough infill, I used 25%

Thanks! Making a big difference being able to get enough tension!

my anet a8 set its self on fire so this is for every one replace the crimps on the psu with high temp crimps and put on a mosfet and new psu if you can

what do i need to install this?

Everything is explained in the readme.txt file

Can you make this to fit a gt2 toothed idler? Or does anyone know of one that will?

I don't have a toothed idler to take measurements or test it, but look through the remixes, I seem to remember somebody already made one.

I found it. Thank you for the reply. https://www.thingiverse.com/thing:2043719

Anet A8 X-belt Toothed Idler Tensioner
by butchja

How long should be the belt plz?

The belt needs to be approx 10cm longer. See the readme.txt file for details about making and installing this tensioner.


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 Y-belt tensioner too !

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


Need to buy a new belt. What belt length should I buy? (don't have my printer close by to check)

If you do not already have a an answer...buy 2 or more metres.... avoid the rubber only type - they soon stretch. having more metres in spares, saves unexpected belt problems holding you back or waiting for a slow delivery.

very well....this thing is perfect for a good tension belt x anet a8. make .after read the .txt for installation. thank's very much ^_^

print 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!

My Axis rods extend out the right side by nearly 1.5cm. I keep reading to tap them with a hammer. I did and i seems like the bottom out and i don't want to hit them too hard. Any thoughts?

Also, what % infill do you print this at?

Check that the rods are the right length, mine are 440mm. Also, measure the depth of the hole in the left block then push the rod in and mark where it stops and compare that to the depth. I wouldn't hit it with a hammer, but it it's not going in all the way try something to apply steady pressure like a large vise or a woodworking clamp. For infill, 25% should work ok.

Fitted at the same time as steel belts.

thank you for making and sharing

For those who struggle finding M4 screw, you can make the nut holes bigger using Google Sketchup. I modified mine to fit M6 screw bought at Home Depot, which have the nut size of 7.8mm. I also modified the two prongs so they can fit in perfectly with the slider. Anyway, thanks for the original

Comments deleted.

This project was very helpful to this 'newbie'. Thanks!

Comments deleted.

What can I do to make this work? my x-axis rods stick out past the frame by about 1 cm

Use a hammer and give them a little tap. Those fittings are tight. Believe!

How wide is the gap for the idler? I recently bought some toothed idlers for 6mm wide belts, but as they're 11mm total width the gap in the x axis mount is too narrow, so I'm looking for an x tensioner like this that has room to fit them..

Hi and thx for you design
I printed it and would like to try it out, but unfortunetaly it doesnt fit.
the two rods don't fit through the slit in my x carriage.
since i wanted to print another x carriage as a spare part anyway:
could you please link an x carriage that works with this design?
that could help others with that problem too.
thanks for your kind help in advance
greetings from germany

What is the recommended fill density for this part if I print in PLA?

Hi, Great design, very stable and works perfectly. Thanks for providing it for us to use.
Carry on with the helpful designs.

This is a solid solution to the issue of belt tensioning.
I've tried others, but they are all so weak.
This takes the belt outside the frame using the existing bearing and allows a good strong hold on the belt tension.

The only slight downside is that it requires a slightly longer belt, but you should all have some spare in your parts box!

Many thanks for this design.

Yes, I agree. Love the design and results. Unfortionately I had already cut my belt prior and not enough left over. My solution was 2 large zip ties on each side to make up the difference.

Hi freemark! I like this design but how does heating the 4mm nut make it stay into the hex slot of the print? I'm new to all this so thanks

The slot is slightly too small. Heating the nut softens the plastic so it gives when you push it into the slot, then when it cools the plastic conforms tightly around the nut.

Thanks mate it worked beautifully! The nut went in alot easier than I thought.

You're welcome, glad it worked for you.

Comments deleted.

hey, i, super stoked to print this but before i do i was wondering if my belt would be long enough. Its already stretched and cut for my original setup? Did you need to get a new belt?

The belt will need to be about 4 in (10cm) longer, there's more info in the readme file. I did get a new belt, but because it was thinner and more flexible than the stock one. Having the extra length for this tensioner was a bonus. While you're at it, you might want to print a better belt attachment, like one of these: http://www.thingiverse.com/thing:1433295, http://www.thingiverse.com/thing:1685768 or http://www.thingiverse.com/thing:2016779

belt attachment part for Anet A8
by Simhopp
Anet A8 prusa-i3 X-belt holder
by Sjouke
X Belt holder part for Anet A8 and Prusa I3 only for GT2 Belt 1.3-1.4mm
by kiss1

How much does this improve print quality? I have already assembled the printer and have been printing for a while. Does the belt stretch and need periodic tensioning to keep the quality the same?

Yes, the belt will stretch over time. You get the best print quality when the belt tension is set correctly, not too loose or too tight, and this tensioner makes it much easier to adjust. Also, with the original configuration, tightening the x-belt will squeeze the z-axis rails toward each other which may cause binding. This tensioner eliminates that problem by putting the tension on the ends of the x-axis rods instead of the right z-axis bearing block. You can google for details on setting the correct belt tension.

In the second picture the part is shown with some bolts and some nuts. Does anyone know the exact ones shown there?

Look at the readme.txt file, it explains everything.

How did you get the M4 Nuts in there? The Holes are too small :(

4 ANSI Screw nuts fit in perfectly...

The instructions are in the Readme file. Thread the nut onto the screw, and hold the screw with pliers. Heat it up for a few seconds with a cigarette lighter, then carefully press the nut into the hole and let it cool. This embeds the nut so it doesn't fall out.

Why do you copy toolsons X-belt tensioner almost 100 percent and claim it to be yours???
Thumbs down!! At least add it as a remix!! Shame on you

Sorry but you are absolutely wrong, this is 100% my idea and I designed it from scratch. I have no idea who toolson is, but if he/she made a similar tensioner it's only by coincidence. Shame on you for making unfounded accusations !!!!

Anyway, this design is too complex and doesn't make the belt tension adjustment easy. Two screws to turn and you can't use a scale to measure the tension.

lol. It's not even similar, it is just the same.

P3steel 2.x - X-axis complete
by toolson

Now that you provided a link, I looked at the stl files and they are most definitely NOT the same, they are similar. But that doesn't matter because my design was done without any previous knowledge of the one you are referencing. I do not appreciate you coming here trolling and making false accusations, so please go away.

Who cares ? The idea is the same and not much to "invent" here. Problem solved more than a century ago when belts were made of leather :)

MKSA, just letting you know that I'm ignoring your comments since you don't have anything useful to say. Please take your trolling elsewhere.

thanks for being so helpful

Too much JUNK in this world and naive people buying it !
You resort to personal attack instead of proving you are right.
Call it "trolling", not my problem. If you can't accept criticism, you are one step below ignorance.

stfu, who cares? he's helping people. Its a good thing the world automatically purges itself of people like you. Go crawl up someones arse and die fool!!!

Is it ABS? If so, are the 3d model parameters already adjusted so as to consider post-print shrinkage? Or do you have to adjust the model scale before printing as per your plastic properties?

It's PLA, so you don't have to worry about shrinkage or dimensional stability. No scale adjustment is needed as along as your printer is calibrated. You will need to do a little post processing, see the readme file for details.

How do you install it?

You remove the existing Bearing and belt, Re-seat the bearing inside the slot of the tensioner might need to get a longer belt 1 meter is good thread the 2 screws in with bolts on opposite side (these tension the belt) and do your belt up again and tension it up.