When to replace those X, Y belts?
Hi, I often have prints with random horizontal lines. Will replacing the X, Y belts reduce the chance of getting these unwanted lines? My machine is two years old.
Are the belts tensioned?
The way I've always understood it is that if you hold the respective motor shaft tightly with pliers, if you cannot see any 'slop' or 'play' when attempting to move the respective axis, you are good.
RE: When to replace those X, Y belts?
I always try to make them as close to the recommended values and within ranges as possible. What do you mean by 'slop' or 'play'?
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 is 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 is smooth?
Retighten the belt until it just begins to make a low musical note when plucked...
Make your next print this:
https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus
It MUST be printed in Prusament PETG or the spring tension will be wrong.
Cheerio,
By 'slop' or 'play' (possibly Stateside terms) I mean that when the motor shaft is held firmly in place, it should not be possible to move the corresponding axis manually at all.
They should behave as if they are fixed in place.
On the other hand, the belts should not be so tight that they prevent the axes from being moved manually when the motor shafts are not being held. The axes should move smoothly by hand.
TFM says to tighten the belts until they sound like a bass guitar string when plucked, which is not a very precise measurement.
However, my 'other' printer (Ultimaker S5) has several belts and for the shorter belts they (TFM) use the guitar string analogy as well. For the longer belts they use the 'no play' criteria.
There are also a few 3d printed belt tension gauges in the Prints section.
I think the proof is in the prints, however. If you can print a larger calibration cube with smooth vertical surfaces, the belts are not too loose or worn.
RE: see this article
https://prusacommunity.com/your-belt-status-and-you/
When to replace the belts? If they are not damaged, never.
RE: When to replace those X, Y belts?
I printed the tension meter and adjusted the X and Y belts separately so that the arrow points to around the middle of Min and Max. Then, cleaned and lubricated the X and Y rods. Next, I performed the belt test. After the belt test, I got X: 248, Y: 273.
With the power off, I moved the axis by hand. What is the definition of "smooth" here? Do you mean butter smooth? It was kind of smooth but I certainly felt the steps when moving the X and Y belts. I felt the steps more pronounced on the Y.
For both belts, they touches the inner edge of the respective silver-like pulley. Is there a problem with that?
Prusa Support told me that I don't need to do anything to the two vertical threaded rods. Certainly not to lubricated them or using IPA to clean them. Is that really true? Sometimes they told me things that are wrong.
Belts are good stuff
Harley Davidson has been using Gates belts for final drive since 1984. Replacement interval is never.
I used to sell Cygnet 12” optical jukeboxes the size of small Manhattan apartments, running Gates belts. Replacement interval was never. Frightening, ferocious machines.
My trike has a Gates belt final drive. Replacement interval is never.
if you think you have some funky chicken going on, it is not the belt.
Don’t trust forum advice.
RE: When to replace those X, Y belts?
With the power off, I moved the axis by hand. What is the definition of "smooth" here? Do you mean butter smooth? It was kind of smooth but I certainly felt the steps when moving the X and Y belts. I felt the steps more pronounced on the Y.
For both belts, they touches the inner edge of the respective silver-like pulley. Is there a problem with that?
Prusa Support told me that I don't need to do anything to the two vertical threaded rods. Certainly not to lubricated them or using IPA to clean them. Is that really true? Sometimes they told me things that are wrong.
If you can 'feel the steps', as in a point of resistance for each tooth of the belt, it's probably too tight.
When you say 'touch the edge of the respective silver-like pulley', if the belt is not centered, loosen the grub screw and move the pulley on the shaft until the belt rests between the flanges on the pulley.
As to not lubricating the Z axis, the Party Line is not to do it, and I interpret that two ways. First is that they (those nuts that fit on the threaded shafts) are expected to last for the life of the machine, as in 'replacement interval: never' (I like that saying), and second is that if any play develops, it's time to replace those nuts.
Last year with the old firmware, the aim was to tune the X Y belts to 275. Then, Prusa changed the firmware and I was told that newer firmware are not as strict as before so there is a larger range of acceptable values, if I recall correctly could be as low as 240. Since tuning the belts based on values still have horizontal lines appearing on the prints, I used the tension meter to tune the belts' tension. However, I still feel the "steps" which according to you is too tight. So, which method of turning the belts' tension is the best? When I first made the post, X was about 260s. Then, after using the tension meter to tune the belt to around the middle of Min and Max, I got 248. So I wonder which is the best way to tune the belts.
I don't know. My gut says that if you can feel the steps, there is at least some mechanical binding.
You might feel the magnets in the stepper motors as you turn them, that's OK.
For both belts, they touches the inner edge of the respective silver-like pulley. Is there a problem with that?
It's very difficult to prevent. As long as there's no significant wear to the belt don't worry.
Do you still get the same horizontal banding?
Cheerio,