Belt Tensioner , do you recommend ?

Hi

Guys I have a heated bed that's 400x400 running on two 20x20 Extrusions with wheels.

My question is I see some people add a Belt tensioner. ( The cloths peg type tensioner ). Would you recommend it.

The belt from the stepper motor to the bearing ( Nut Tension ) to tighten up the belt is pretty long. So wondering if you add the wire tensioner in the middle of the belt would be beneficial.

Thanks

Yes I always recommend a belt tensioner. - At least in my workshop temperatures can vary by about 10° - Temperature changes length of objects - so for me it is essential to have the clothes peg type tensioner - no fixed one.

Only drawback I know: You have to lower jerk and acceleration, else it would stretch and compress with every move.

Absolutely not. Never put those things on your printer's belts. Those springs make your belts do the exact opposite of what a belt should do. The belts have glass core- they don't expand any amount that matters when the temperature changes. Pull the belts tight and leave them at that.

Clothespin spring tensioners should be in the 3D printer error hall of shame, right along side 4 screw bed levelers and acrylic printer frames.

Edited 1 time(s). Last edit at 12/05/2017 07:35AM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I designed and use a simple belt tensioner [www.thingiverse.com]

Probably one of those clothes-peg springs would be just as good; I never thought of them at the time.

Clothes peg springs add backlash - - everytime the motor changes direction, it allows the spring to go slack before tightening again. It might not be much, but it's certainly more then the thermal expansion of the belt in different temperature ranges your printer throws at it. If thermal expansion is really an issue (it's not) then thermally shielding the belt somehow would be your first go to.

Yeah I'd go for some sort of fixed-tension tensioner with a screw or similar not a clothes peg spring.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Belt tensioners are useful if you can‘t be bothered to adjust tension correctly. They introduce elasticity where you don‘t want it.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

These springs are most of the time improperly mounted with their "arm" resting in the space between teeth.
To install, you need to pull hard or put them on a belt that is already somewhat under tension. In that later case, you need some good nozzle pliers if not steel fingers !
Anyway, you must be close to the mfg spec (about 12 N for GT2 6mm w). In that case, they somewhat work, looks like it doesn't introduce too much elasticity. I tried it on a prototype and didn't notice difference when I removed it and tensionned the proper way.
Of course, if too loose, don't expect good results.
Fact is, a proper system is not that complex to make and far easier when it comes to install and tension the belt.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

if you have a Prusa type printer. Then there are nice tensioners available.
I use the first one until now it works very good
[www.thingiverse.com]
[www.thingiverse.com]

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P3steel DXL, with Due/RADDS/Raps128 dual Wade's extruder

Quote
amigob
if you have a Prusa type printer. Then there are nice tensioners available.
I use the first one until now it works very good
[www.thingiverse.com]
[www.thingiverse.com]

Sorry, not nice, too complex and not easy to adjust.
Should be either at the idler pulley, motor, eventually integrated in the carriage where the belt is fixed, must be simple, keep the belt straight, be accessible and if possible adjustable with only one screw.
A few can be found in Thingiverse. Some kits have correct systems too.

Edited 2 time(s). Last edit at 12/10/2017 05:46AM by MKSA.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Thanks Guys for the advice, much appreciate. I decide not to use the spring method , just a bolt tensioner that pulls the belt tight & make sure it stays like that. Its been working fine and good results from my prints.