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Belt Tensioner , do you recommend ?

Posted by scubi 
Belt Tensioner , do you recommend ?
December 05, 2017 02:21AM
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
Re: Belt Tensioner , do you recommend ?
December 05, 2017 04:09AM
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.
Re: Belt Tensioner , do you recommend ?
December 05, 2017 04:33AM
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 04:35AM by the_digital_dentist.

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Re: Belt Tensioner , do you recommend ?
December 05, 2017 10:11AM
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.
Re: Belt Tensioner , do you recommend ?
December 05, 2017 02:55PM
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.
Re: Belt Tensioner , do you recommend ?
December 08, 2017 04:59PM
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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Re: Belt Tensioner , do you recommend ?
December 09, 2017 12:04PM
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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Re: Belt Tensioner , do you recommend ?
December 10, 2017 12:50AM
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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Re: Belt Tensioner , do you recommend ?
December 10, 2017 01:39AM
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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Re: Belt Tensioner , do you recommend ?
December 10, 2017 02:43AM
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 02:46AM by MKSA.

"You failed to maintain your weapon, son" (Harry Brown )
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