Tension belt limitation?
i was trying to increase the tension on the X and the Y belts for my MK3S but it seems like there are limitations, the handbook says you should aim for between 240-300. The max i can get with Y is only like 258-268 and X is around 264-281, i have tried to tighten and looses the MAX possible to with X and Y Belts but cant seem to get out of that range i was trying to get the numbers near 290-295 so as to create less friction for the belts.
Do you guys have limitations on your belt, is this normal? or should i be able to go below 240 and/or higher then 300?
(page 75 of the user handbook).
RE: Tension belt limitation?
Wack it with your finger. If it feels like a guitar string - you are too taut and may do damage. Loosen it.
If it does not droop - you are fine. If it feels loose - and droops - tighten it.
I wish Prusa never published those numbers. It leads many to tighten too much.
Much more important is for the X and Y axes to move freely from side to side with the power off. If the axis binds - find out why and fix it.
RE: Tension belt limitation?
ya i was wondering too right now my numbers are X: 265 and Y:263 but the Y is loose compared to X not sure if that is normal?
also if i should just base the tension on how the 2 belts feel tighten/loosen them till they feel the same and disregard the numbers?
RE: Tension belt limitation?
Those numbers reflect drag on the motor. They are only roughly related to tension.
It is sort of subjective - if the belt does not feel too loose or too tight - it is fine.
You don't want the belt jumping pulley notches or bending the frame. Somewhere in the middle of that is good.
RE: Tension belt limitation?
based on the calcs in the doc how did you apply and measure the right tension?
RE: Tension belt limitation?
I've used a trigger pull scale - a bit crude - but effective. I've also made a custom balance beam that applies 250 grams pull to the belt.
Move extruder full left, and bed full back. Pull up midway on the lower belt of the two pairs with 200 grams, and you should see 12/64 deflection on the Y axis and 15/64 deflection on the X axis. This reflects about six pounds force static tension - about the spec limit for the motor bearings.
Increase the pull to 250 grams, and static tension is closer to 7.5 pounds, which may exceed the radial load bearing specs a bit, but belt will stretch and wear over time reducing the load the motor sees.
Minimum for the belt teeth to properly engage the drive gear is 2 lbf. As an aside, I've used much higher tension, as high as 25 lbf, but don't see any benefit to going over 6-8 lbf.
RE: Tension belt limitation?
A tension meter I kind of like is:
https://www.thingiverse.com/thing:2230598
RE: Tension belt limitation?
That meter has no calibration so it's 100% guesswork for what the actual belt tension is.
RE: Tension belt limitation?
It is used to equalize tension between your belts, which it does very well.
In my opinion, this is more useful than chasing specific numbers.
RE: Tension belt limitation?
If all you want is equal tension, then so does a clip on spring.
RE: Tension belt limitation?
I never liked this way to verify the tensions. Since it was introduced I think it caused more harm. People are trying to reach certain numbers and sometimes damaging their printer.
I would still recommend to use the old method ("playing the string"). And verifying the belt doesn't slip.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: Tension belt limitation?
I never liked this way to verify the tensions. Since it was introduced I think it caused more harm. People are trying to reach certain numbers and sometimes damaging their printer.
I would still recommend to use the old method ("playing the string"). And verifying the belt doesn't slip.
how do you generally verify that the belt doesn't slip?
currently i am having lot of Y crashes when i print a part orientated a certain way on the heat bed? other orientation dont seem to have as many crashes for the same part
i have tighten and loosed the Y-tesion but to no success also i have left space on both sides of the barrings also still cant get rid of the crashes, only conclusion is maby the filament is hyroscopic, maby change multiplyer rate, or slow speed down currently at 100%.
RE: Tension belt limitation?
By fixing the motor position (for example turn on the printer and move the axis from the menu). Then just grab either the extruder head or bed and try to move it by hand. Usually you can move the whole printer before the belt slips. You will be surprised how much force is needed for that.
I'm not using crash detection at all. But if you have issues with it then the most likely reasons are:
- Hardware issue - Like dirty/damaged bearings
- Operator issue - Curling filament
"other orientation dont seem to have as many crashes for the same part"
You shouldn't have any crashes at all. Crash means the motor experienced unusual high amount of resistance. Such a thing shouldn't happen during normal operation.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: Tension belt limitation?
depending on the motor and friction the tolerance to trigger the crash detection can be very small. filament peaks from retracts/Zlifts , part warping, infill unevenness can all cause "crashes"
RE: Tension belt limitation?
By fixing the motor position (for example turn on the printer and move the axis from the menu). Then just grab either the extruder head or bed and try to move it by hand. Usually you can move the whole printer before the belt slips. You will be surprised how much force is needed for that.
I'm not using crash detection at all. But if you have issues with it then the most likely reasons are:
- Hardware issue - Like dirty/damaged bearings
- Operator issue - Curling filament
"other orientation dont seem to have as many crashes for the same part"
You shouldn't have any crashes at all. Crash means the motor experienced unusual high amount of resistance. Such a thing shouldn't happen during normal operation.
I am using the Silver/Gray PLA it drips out of the nozzle even when the nozzle is at rest but heating up to PLA temp, but drops straight down, also i measured the filament diameter its 1.69 average, currently my extrude rate is at 1 i have been using the default settings that are in the prusa PLA profile i am assuming they are good enough.
Can PLA get Hydroponics fast and i have been using it for like 2 months or so when i assembled my kit have not dried it ever since, i print in the basement i have a humidity detector i got from ali-express, they usually range form 60-80% they have been closer to the higher range for the past few days.
thinking of doing then cube test and the filament diameter and changing the profile setting based on that see if that helps
RE: Tension belt limitation?
If you are having crashes: check the LCD status for the belt tension menu.
Ignore the term belt tension, think of the numbers as BEARING SMOOTHNESS, the higher the better.
200 == bad, bearings are likely crimped/crushed
250 == could be better
300 == good
Anywhere between 260 to 280 is pretty normal if you have lubricated bearings.
Filament moisture content won't cause crashes. Moisture causes all sorts of other problems, so needs to be controlled, but that is not why your printer is crashing.
RE: Tension belt limitation?
ya my are X:262 Y:254, if lets just say you have a higher filament diameter, in slicer then the actual average of the filament diameter and i am assuming this will shoot out more filament, can this cause crashes since it could extrude more filament and potently cause curles?
also is there a print i can run to find if a specific barring which could be messed up or not sticky enough etc... like for example print something in the corner of the bed and see as the bed goes back and forth if that causes crashes etc....
RE: Tension belt limitation?
If you are having crashes: check the LCD status for the belt tension menu.
Ignore the term belt tension, think of the numbers as BEARING SMOOTHNESS, the higher the better.
200 == bad, bearings are likely crimped/crushed
250 == could be better
300 == goodAnywhere between 260 to 280 is pretty normal if you have lubricated bearings.
Filament moisture content won't cause crashes. Moisture causes all sorts of other problems, so needs to be controlled, but that is not why your printer is crashing.
ya my are X:262 Y:254, if lets just say you have a higher filament diameter, in slicer then the actual average of the filament diameter and i am assuming this will shoot out more filament, can this cause crashes since it could extrude more filament and potently cause curles?
also is there a print i can run to find if a specific barring which could be messed up or not sticky enough etc... like for example print something in the corner of the bed and see as the bed goes back and forth if that causes crashes etc....
RE: Tension belt limitation?
I probably should readjust my belt tension, but for some reason my tension on the Belt can't seem to go above a certain limit. The X belt can't seem to go above 281 and Y can't go above 268.
How do I get my belt tension close to 300, I greased the rods when I initially got them should I add in more grease perhaps I didn't put enough or should I just consider getting new bearings and belt
What have you all done to get your belt tension close to 300.