Belt Tension Device? (BTD)
The forum is littered with the woes of correct belt tension ...
I still struggle a bit with the right tension. The description in the Build manual (pressing the belts together with two fingers / not slipping over gears / no slack) and the readouts for 240 +-40 really don't seem to match. I'm afraid I'd just break stuff when I aim for 240... But i really don't know. 😥
Would it not be possible to design a simple mechanical system to tension the belts? I'm thinking of some printed mechanism plus some standard weights (standard weights, or maybe coins? as an alternate) that would apply a force to squeeze the belts together and read out a distance between the belts.
Let's call it a "BTD" (Belt Tension Device)
Yes, I realize there are standard tools for this ... but I'm thinking cost ... and the system would not work without a good number of folks participating and providing calibration points.
The weight of Coins in various currencies would need to be measured against standard weights, so we could compare.
We could calibrate BTD values against Prusa's "dimensionless" readouts.
We could also get a sense of the range of BTD readouts that "work" for folks ...
And, of course, the maker who designs the "winning" device ears 1400 "Prusa Points" (my invention ... good for a free ?? from Prusa??)
-- Clint Goss
Re: Belt Tension Device? (BTD)
When it is just about measuring belt tension, I really wish more people would adopt the frequency method. It is easy, precise, fast, and super cheap, if you have a smartphone already. See https://shop.prusa3d.com/forum/others-archive--f66/use-free-span-frequency-hz-to-check-and-set-belt-t-t12576-s10.html#p73398 .
Re: Belt Tension Device? (BTD)
When it is just about measuring belt tension, I really wish more people would adopt the frequency method. It is easy, precise, fast, and super cheap, if you have a smartphone already. See https://shop.prusa3d.com/forum/others-archive--f66/use-free-span-frequency-hz-to-check-and-set-belt-t-t12576-s10.html#p73398 .
I tried that when truing wheels but in the end found I prefer the Jobst Brandt tensiometer when I build wheels, ooh an idea for Thingiverse. For the Prusa, I've fiddled with belt tension quite a bit and at least as it currently stands find that as long as the belt has a little tension on it, e.g. the "pinch test", there's little or no discernible difference in print quality between a heavily tensioned belt and an almost slack belt. All of this might change once the firmware is dialed in though.
Re: Belt Tension Device? (BTD)
https://www.thingiverse.com/thing:2230598
But there is no reference. If someone with perfect tensioned belt can test it and give us a scale/value we can optimize it.
Thomas
Re: Belt Tension Device? (BTD)
Here's how I set my belt tension.
1. Put the belt on. Is it sagging? You are good. If it's "straight" you are WRONG.
2. Feed the belt 1 tooth into the holding teeth, 1 tooth at a time. (2mm) Until the belt is straight, with NO sag.
3. Do a test print. Is the belt staying "straight" (a bit of twisting is OK)
If the belt "jumps around" at all, try increasing the tension by another 1 tooth (2mm)
🙂
Basically, just keeping the belt 'straight' and 'not jumping around' is a properly tensioned belt.
Experience:
I like printing big things fairly fast, and small things slow. I don't like ghosting on my big things, and I don't like ANY sign of it being 3D printed on my small things. The printer must be perfect to perform both of these. 🙂
Hi, I'm Sean. I used to work on CNC machines.
I try to not make mistakes, but the decision is YOURS.
Please feel free to donate to my filament/maintance fund.