Wonky x-axis
Lot of trouble with x-axis stuff the last few days.
As posted by another owner, my printer loses the location of X home. Only time it finds home properly is when I manually move the carriage all the way to the left, whether with power on or off, before giving the Auto Home command. When the printer manages to complete a print properly, it does not go home, but relocates higher and closer to the left. If I then give the Auto Home command, it moves to the proper Y and Z locations, but does not change X, so is way to the right of what should be X home. If the print fails, which has become very common lately, whatever the X location is when it completes Stop Print, that's the new X Home Location.
Think I also have problems with Z, but there it's with losing the Live Z adjustment. Or when I finish with my favorite calibration gcode, and the carriage moves all the way to the top, when I try to Auto Home or just start a new print, without changing X at all, the printer drives the nozzle all the way down into the table, shoving the table down noticeably, then issuing a failure message, something like "Z leveling forced." I can't drive the carriage down from that high position using the Move Z command because the printer will not accept negative values of Z. I'm hazy now on exactly how I've recovered from this situation. Think what I've done is either to allow the head to drive down and tilt the edge of the table, from which I can Z up, or I shut it off part way down, then manually move the carriage all the way to the left and hit Auto Home.
I suspected problems with X belt tension, so did some work on it. I wasn't able to pass the Self Test, failing a couple of times on the Print Fan, then it started working again, at which point the printer failed the X axis test. Belt tension now reads 204. It's been higher and lower. The carriage is noticeably harder to move than the table (Y axis), which does not seem right, but I do not remember that it was ever as easy to move as the table. Manually moving the carriage (hot end), I do not find any particular hard spots, just general resistance. I had been using Stealth Mode for a couple of months, having more success with that change, but decided yesterday to try a simple print (like the PRUSA tag) on Normal Mode, and the printer very quickly put up a Crash Detected message and halted.
I do not know how a crash is detected, but I have hypotheses. Maybe someone here has detailed knowledge of such, and of stepper motors. I hypothesize that the printer calls crash when it detects resistance to movement. So how does it detect that resistance? Could be current, some kind of way, but I don't know. I understand that stepper motors receive current pulses, one for each step. I hypothesize that the printer assumes a step was taken when a pulse was issued, and adjusts it XYZ locations accordingly, without actually knowing whether anything moved. So I'm assuming that pulses issued determine presumed position, high current draw is somehow detected and indicates a crash, and if crash detection is turned off either directly or by Stealth Mode, the printer loses the actual XYZ location but doesn't know it.
Whatever, I still need to fix these problems. I'm thinking I'll remove the X belt to see if the carriage then moves freely. If it does not, then maybe I have problems in the bearings. If it does, then I have problems in the belt.
I can't help wondering if some of my problems are either in the EINSY system, or in (a possibly messed up installation of) driver software.
Long post, I know. Thanks for working your way through it! Any suggestions?
Mike
Re: Wonky x-axis
contact prusa online chat system 24/7 support
log into your account on one of the prusa store pages and in the bottom right corner you will see the Chat system box click in it enter your Invoice number for you Prusa and start the chat system they do an excellent job and will take good care of you.
Re: Wonky x-axis
I've been having the same problems with the X-axis. When I checked the tension under Support/belt stats, is said the tension was 212. FAR too tight. I've loosened the motor mount screws, and the tensioning screw, but every time I check, it still says 212.
Any way to get the number to update, and give me the current tension?
Re: Wonky x-axis
Well, I found the X/Y belt adjustment guide, and it says the numbers are updated during the self-test. X-axis is up to 227, but the belt seems awfully loose.
Still adjusting.
Re: Wonky x-axis
The numbers reported by Selftest are not a reliable way of knowing belt tension. If you get low numbers, check alignment and bearing drag. The axis should move freely and smoothly when pushed side to side. If it doesn't move easily, there is a mechanical issue you need to fix.
The belts require making deflection measurements to "know" what the tension is. Move the X-axis to the left, and Y-Axis to the back, apply a 2 lb force to the lower belt: you should see about 3/8" deflection. If 2 lbs lifts the belt so it touches the upper belt, it's a bit loose.
Re: Wonky x-axis
The numbers reported by Selftest are not a reliable way of knowing belt tension. If you get low numbers, check alignment and bearing drag. The axis should move freely and smoothly when pushed side to side. If it doesn't move easily, there is a mechanical issue you need to fix.
The belts require making deflection measurements to "know" what the tension is. Move the X-axis to the left, and Y-Axis to the back, apply a 2 lb force to the lower belt: you should see about 3/8" deflection. If 2 lbs lifts the belt so it touches the upper belt, it's a bit loose.
An inexpensive scale as used in fishing or even for weighing luggage is an excellent way to measure the weight of pull you are applying
https://smile.amazon.com/MANGO-SPOT-Electronic-Killogram-Batteries/dp/B00B301MPI/ref=sr_1_32?crid=QEWFZNFT9BMO&keywords=trigger+pull+gauge&qid=1551471137&s=gateway&sprefix=trigger%2Caps%2C162&sr=8-32
Re: Wonky x-axis
The accuracy of a 110 lb scale at 2 lbs is a consideration. Most scales are spec'd as +/-10% of full scale. At 110 lbs that's 11 lbs. Linearity is almost never spec'd, and accuracy at lower ends of a scale is questionable: what reads as 2 pounds may be 5 pounds. The 22 lb range on the digital above looks better. Though I'd try to find a scale that has a 10 pound range, tops. Trigger pull scales are better candidates, but they cost a bit more.
Re: Wonky x-axis
The accuracy of a 110 lb scale at 2 lbs is a consideration. Most scales are spec'd as +/-10% of full scale. At 110 lbs that's 11 lbs. Linearity is almost never spec'd, and accuracy at lower ends of a scale is questionable: what reads as 2 pounds may be 5 pounds. The 22 lb range on the digital above looks better. Though I'd try to find a scale that has a 10 pound range, tops. Trigger pull scales are better candidates, but they cost a bit more.
Agree 100% and I use a Lyman trigger scale but this looked to be the best of the under $10 scales I could see on offer... an old fashioned fishermans spring balance of the 10lb size would also work but might be hard to find
it would be easy to test by hooking it to the package of meat you got from the butcher/market as those scales that print the lables are quite accurate.