X Axis Belt and Tension  

RE: X Axis Belt and Tension

It seems passing the Self Test was a fluke. I'm failing the Belt Test, with an x length error.

RE: X Axis Belt and Tension

if you can print one of these https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus

i had a problem with belt to slack and number was 246 but was getting layer shifts on the x axis , used this and it sorted the problem, in my post a couple down dan said just to ignore the numbers 

i adjusted the  belt to just under the max marker then ran the self test and it past 

RE: X Axis Belt and Tension

Does anyone know how to obtain g-codes or even stl files for the tension meter, that could be used with PLA or ABS? I don't have Prusa PETG filament, but I'd like to print the tension meter...

Thank you!

RE: X Axis Belt and Tension

Not sure, Prusa specify PETG for this as that what is was calibrated with.

You could try someone near you and see if they would print you one.

https://www.prusaprinters.org/world

RE: X Axis Belt and Tension

@clarmrrsn

Thank you for your response!

RE: X Axis Belt and Tension

@oleg

Any PETG will do.

RE: X Axis Belt and Tension

@bambi

My, newly assembled i3 did fail to on the X-axis. The reason was that the nylon cable cover from the extruder was too tight around the wires. This made the cable too stiff and too short. So the x-axis could not reach the right side of the bed fully and returned an error.

I did loosen the cover, made the cable longer by unwinding it. This solved the x-axis problem 

RE: X Axis Belt and Tension

@diem

It seems the bearing position somehow got shifted some when I was messing with the belts. It was affecting the plate and cable placement which might have been causing the x-length problem. I've moved it back into the correct position and replaced the belt for good measure. It seems to be working fine now.

RE: X Axis Belt and Tensio

I know this is an older thread.....

I have a MK3 upgraded....

Q:   the Belt Test (calibration category),  the X & Y tension, it is supposed to be above 200 reading...  Has anyone figured out what these numbers refer to ?

I determined the higher the number the looser the tension, so 0=no movement (in theory) and 255 (assuming this is the high number) would be loose belt.
My X = 200  Y=245,  seems the 245 on the Y moves freely, maybe a bit loose, but probably is fine since I do not know what the 245 really means.
The X axis seems a bit tight as I have been getting right side layer shift on some taller models, and crashes.

X gantry moves freely side to side, gets a bit tight as it reaches the far right end point, but my other 3 MK2 units also feel a bit tight on the right, so I have to conclude this is just the design.  And when I say tight, not stuck, just not as free as the majority of the center movement...

I tried to print a basic cube for testing, size was 5" x  5" x 5",  it failed about 87% finished, kept crashing on the X axis movement.
Using PLA 215 nozzle 55 Bed  Speed 80mms Using Simplify3D for my slicer... I know use Prusa slicer, but Ihave used Simplify3D for 8 years so I just reach for
it when needed....

I am a bit concerned about the crashing, seems to have gotten worse the last month.
I have cleaned all the Rods, no obstacles or wires getting caught.  I have worked on all of my 5 Prusa machines for years, so my familiar factor with build and 
teardown is good.   
Just this Belt Tension and Crashing is getting old....  Not having the detailed info on how the belt tension is determined is frustration.
Saying the number should be 200 or greater... well    ???
I assume the 200 number is calculated from the stepper motor current draw during movement to determine this number.  But again not sure.

Also I have taken the stepper motor off the X belt and moved the extruder assembly from left to right and the movement tension is pretty much as expected
free from side to side, not binding as it reaches the side end points, so I assume the rods are parallel and clean.
I also do NOT use the supplied LM8UU ball bearings with any of my printers, I use a ball free bearing(mfg escapes me at the moment) but these are far superior
And are about 3x the price / bearing $20ea.   SO:   the bearings are good as I had also inspected these when I disassembled for thr MK3s upgrade.
Putting the clean rod verticle, the bearing freely slide top to bottom.... no not loose, just really good bearings....

I think I will replace the X/Y  BELTS with a new ones, as it has been 4+yrs and I use the printed most every day....

BUT... I am happy to hear any thoughts on this belt tension 'number' and why >200 is good and ????  what is TOO LOOSE ??? 255 ????

Thanks folks

Chuck

The belt tension figure is a measure of the resistance felt by the stepper when moving the axis. On a correctly set up machine this does equate, roughly, to belt tension.

But other things can affect mechanical resistance.

First, with the power off, move the axis by hand; is it smooth? Does the resistance stay the same over the whole range?

Clean and lubricate the smooth rods, check they are not damaged/scratched. Check the idler pulley is not clogged, out of line, or damaged (loosen the belt and try turning it with your fingertip, is it smooth?)

With the belt loose try turning the stepper motor by hand; is it smooth?

Use the link provied by @bigtodski for a meter to help you retension.

Cheerio,

RE: X Axis Belt and Tension

Thanks Diem    as I stated in my initial post, I did all the items you mentioned..

Replaced the belt today, best I could get was a belt tension = 200   any larger (looser) the belt droops....  so decided to just ignore the belt test number and tighten the be lt matching the Y belt tension ( pinch test)  and leave it at that..;

I am suspecting a stepper motor issue (unlikely) or the uP board/firmware....

Either way I have a 8 hour test print going, we'll see how it turns out, 3 hrs in and all is good...

Use the tool linked to by @bigtodski upthread.

Cheerio,