Sudden Inconsistent initial Z-height and ringing on prints
Without any clear reason I've been able to figure out, my printer has suddenly started printing with very inconsistent first-layer z-heights and a lot of ringing problems in prints. I've tried running the printer's self-test which said things seemed OK. I also ran its built-in belt test and got X/Y values of 265,277 respectively which is within the recommended values but I'm unsure of how much that test can be trusted.
I haven't moved my printer or made any other changes to its configuration since this started. It started without any clear reason after turning it on a day ago. What things should I check to troubleshoot this? I'm guessing it's a belt tension issue, but I've found the new browser-based test to be inconsistent and the printer's built-in tester shows no problem based on my limited understanding.
Best Answer by danherbert:
For anyone else encountering a similar problem, after chasing down a number of different possibilities I figured out that my issue was filament feeding tension. I was feeding my spool out of a filament dryer where the spool wasn't spinning smoothly enough.
Filament would come out relatively easily when I pulled manually so I discounted that idea without testing it at first. Eventually I eliminated other hypotheses and came back to filament feeding tension and tested on a simpler filament roller with smoother bearings and my prints went back to normal.
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?
Retighten the belt until it just begins to make a low musical note when plucked...
If the printer works, 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.
Let us know how you get on.
Cheerio,
RE: Sudden Inconsistent initial Z-height and ringing on prints
For anyone else encountering a similar problem, after chasing down a number of different possibilities I figured out that my issue was filament feeding tension. I was feeding my spool out of a filament dryer where the spool wasn't spinning smoothly enough.
Filament would come out relatively easily when I pulled manually so I discounted that idea without testing it at first. Eventually I eliminated other hypotheses and came back to filament feeding tension and tested on a simpler filament roller with smoother bearings and my prints went back to normal.