Cant calibrate I3 Prusa Plus
Hello, having a hard time trying to calibrate I3 Prusa Plus.
I contacted/emailed Prusa but didnt get a reply....maybe they were thinking another idiot who couldnt check forums and made a crazy build...
Purchased recently, instructions were great tried to calibrate the heatbed/glass combo but noticed that im running around in circles after hours and hours and just wanted to know if im missing something. My first 3d printer.
My concern is that ive tried to make a meticulous build, i work as an engineer on aircraft structures so i thought i understood the build process.
-I have leveled the y-axis and checked multiple times prior to putting on pads (guess i can always check again)
-leveled the x-axis
-check glass and seems flat
So now i have it at a point where the left and right sides are similar in z-height but the rear two need to be slightly higher than the front.....looking on the forums this seems to be okay.
However when i raise the rear i always get to a point that the front left z-offset pops up. I'll get to a point where i feel i am close and making last adjustment when the front left pops up.
What concerns me is that this doesnt appear to be too common online, which makes me a little sad thinking i have tried to make a square build.
It appears maybe to me:
-front left hole is to oversize and too loose.
From reading online looks like i could mix and match fasteners and swap them and maybe loosen them a little from the heat bed to allow them to pivot more freely. I have also read about maybe as part of mixing and matching fasteners to screw in fasteners to the z-offset support holes in heatbed holder to slightly oversize them all. Not sure as these holes also located the bed so i dont want to make it too sloppy or im sure parts will suffer. A better design would have some bed locating pins separate to the z-offsets so opening up the hole diameter doesnt mean the bed can move around.
Also thought about maybe using some goop or plumbers tape or something to take up the slack until that gives out 90% through a 20hr print :S
Again this makes me nervous that i would assume other people would be more heavy handed and tighten their heatbed holes more than me and still the forum is not full of people that cant calibrate (ive maybe seen two entries)
Also saw in thingiverse a design for a z-offset knob 'tie-down' holder, so guess this seems to be an issue.....but id need to be able to print first to get one of these out. Or get long M4 bolts and ziptie the end coming out of the heatbed holder to give just enough friction. but not sure if ive found the actual cause and this is a bandaid.
So wondering if ive missed something or got a kit where a few things just got slightly out of tolerance and im just screwed. Trying not to let it get me down but dont wanna get to point where it takes me more time to calibrate than building the thing - as my time is at a premium right now.
have i missed something.
help...
Re: Cant calibrate I3 Prusa Plus
Hi George
I think what you are saying is that when you get close to calibrating, you are finding that two diagonally opposite adjusters are OK and the other two are high?
If so, then this is typical of a twisted Y chassis, although you have said that yours is square. I would really recommend that you remove the felt pads from the corners and check again.
Also, you might want to loosen the 4 locknuts under the heated bed, heat the bed to 50 degrees and re-tighten the nuts; this will ensure that the adjusting bolts are fitted properly into the Y chassis holes.
There is also a possibility that the heated bed is more warped than usual; use the edge of a steel rule across its diagonals to see if it is level; if necessary, you can flex it a tad (when warm - not hot...) to straighten it a bit (the heater does not need to be perfectly flat; the glass will compensate somewhat).
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Cant calibrate I3 Prusa Plus
What i meant was that the left and right side seem fine prior to calibration. However the rear two need to be raised more than the front two.
As i raise the rear two it seems to get to a point where the front left pops up.
This is like potato chipping effect. Im guessing that the rear two and front right have reasonable hole tolerance and enough friction but the front left doesnt and just slips out and goes along for the ride.
guess i can check y-axis again, but again saying the left and right seem okay but when raise the rear the front left pops up.
Re: Cant calibrate I3 Prusa Plus
lock nuts where tightened after heatbed was at temp.....but keep suggestions coming...i need them!
Re: Cant calibrate I3 Prusa Plus
the left and right seem okay but when raise the rear the front left pops up.
So the front right and rear left are in position and the opposite two see-saw. Frame twisted. Or the other items I listed.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Cant calibrate I3 Prusa Plus
Okay i guess i can check y-axis again.
But as i was saying prior to calibration with the z-offset moved about the same amount 2-3mm there is no see-saw, or when there is no gap between lock-nuts there is no seesaw. but once i start raising the back past about 50% more than the front....then yes the front left moves up and down but the back right does not move.
Re: Cant calibrate I3 Prusa Plus
its the front left that always moves up/down whether the y-axis is pulled all the way forward or pushed all the way back.
Re: Cant calibrate I3 Prusa Plus
Okay will check y-axis again and check measurements before i loosen the bolts.
Just have a hard time believing that after all the measurements during the build that im out of range so far that the general slop in the machine cant account for it, (while seems 98% of people have no issues).........as im going to have some small amount of warp no matter what.
So will update....in hopefully better mood.
Re: Cant calibrate I3 Prusa Plus
Also how do i contact Prusa cuz i asked them the question for more insight but i didnt get a reply....assumed i get a reply something like "thats unfortunate...here are some forum links" or "we found that such and such might work better"...but nothing which is a surprise as many online reviews state that they replied fast.!!!!!!
Re: Cant calibrate I3 Prusa Plus
george
Hi,
the problem is really in twisted Y axis. or that Frame is not square to Y axis.
If you dont want to adjust it and just start printing , take zip-ties and fasten heatbed to Y axis. Then make that 4 point calibration and that in all points the height is exactly same.
Something like this (zip ties in corners)
Re: Cant calibrate I3 Prusa Plus
Okay i'll try aligning it again, taking off felt pads and checking it again. Let you know.
I thought to ziptie the stubborn corner but again its not a pure solution.
I was hoping to set this up quick and have it in my closet when i wanted to play with it or needed it to fix something as i have too many other hobbies but starting to get the idea that 'bootstrapping' this stuff is the norm and its gonna suck me in until i have no life and possibly not something i should depend on if i need something urgent 🙄
Re: Cant calibrate I3 Prusa Plus
George
For what its worth I was printing with this printer in little over 4 hours after starting the build. I had read the instructions several times to ensure I completely understood what was required.
Like many other users, I had no issues with the build, instructions and printer. However, I did start the build by making the assumption and working on the premise that I was a complete and utter idiot. I refuse to comply with the "again, again" brigade and my methodology appears to help in many things, including this build.
Yes, I have had issues since, but they have been resolved quickly and easily by using the KISS strategy.
I too have many hobbies yet I have been able to keep my printers busy almost 24/7 for over a year.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Cant calibrate I3 Prusa Plus
I know i hear you..... it must be something wrong with me....
I read reviews, read pdfs before purchasing, on phone on computer, read manual a few times before starting build, and preflight guide and youtube videos....
As has been discussed prob a build up of a few tolerances came into play and i'll adjust it and eventually get it to work...
But please work on autolevel in next version, or 3 point level, separate plate positions locator compared to z-offset adjuster.
Its a personal thing...im kinda at that age now when mommy isnt cooking my food and washing my laundry and daddy is off at work.....with family, work and hobbies as i mentioned its frustrating to get nowhere after a couple of hours...when schedule is usually down to a couple of minutes on things.
Re: Cant calibrate I3 Prusa Plus
George
I totally understand your frustration. When I received my first printer (a Chinese clone) it had a bad solder connection on the motherboard for the E motor connection. It took over a week to resolve that.
Personally, as well as having 2 kids and a full time job, I play around with electronics (Arduino/Pic etc) and have to help the wife out with her exhibitions/museum/farm/models. But I still have time to keep the printer going...
I bought the printer initially so that I could print buildings for the model railways. So far not one of my prints has made it onto a railway...
This printer is a great printer for the money. And support is usually excellent also, but bare in mind that buying a kit, the support is officially limited to this forum. However, you will always get a response if you use the "live chat" facility on the shop pages.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Cant calibrate I3 Prusa Plus
George
I had a similar issue with my genuine Prusa I3 build. I have a level base. But one end the back left would not seat on the Y bed. I tried loosening the lock nuts and heated up the bed and then tightend as suggested. Now the front right does not seat properly 😆 This is a poor design for levelling the heatbed. Most clones of the Prusa I3 use spring loaded bed adjusters that do not rely on gravity. I wonder why 😉 In fact most 3D printers of cartesian design use spring loaded adjusters to level the build plate.
KISS is good if it isn't stupid.
As Peter says, live chat on the Prusa shop site will get you answers direct from Prusa.
Nigel
Life is keeping interested and excited by knowledge and new things.
Re: Cant calibrate I3 Prusa Plus
All wells that ends well..
So went home tonight ready to figure this out. Threw away felt pads and resquared y-axis, actually it was pretty square but when the prob was with the attachment to the x-axis holder frame, front right was a little higher by half a mm...(or maybe my table is bad :)).
I checked the heatbed and it looked okay and mostly flat. After doing all this i also heated the bed and then tightened the bolts at the z-offset again.
I also turned the z-offset so the bed would be almost at its lowest position at all four points.
Then i started the calibration again. This time things were much better, but then just near the end the front left came up slightly again! Not near as much as before but it did come up slightly. This time as i hoped i could play with it to get the calibration done, while before i was really out of bed and couldnt do anything.
So this time i moved the clips holding the glass closer to the middle and slightly away from the corners. Not quite sure if the glass was bent slightly or the heatbed was warped but at that level i may never know. And with this adjustment i was able to calibrate and just finished printing the PRUSA PLA logo and looks great.
I also took more care turning the knobs and turning more than one at a time at the start to help prevent overshoot and causing it to take longer to calibrate.
So now i guess its onto the slicer software. Its a brave new world 
(not saying felt pads are useless as i felt the vibes during the print but i'll try to find something else in the future if i need support
Re: Cant calibrate I3 Prusa Plus
George
Best to use anti-vibration feet. They lift the corners anyway, so the pads are quite useless.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Cant calibrate I3 Prusa Plus
Yeah im in the groove now....wish i could delete some rants in previous posts but thats life, guess was a long day yesterday!
Re: Cant calibrate I3 Prusa Plus
George
Best to use anti-vibration feet. They lift the corners anyway, so the pads are quite useless.
Peter
I used the anti-vibration feet for a long time but have taken them off. I was getting some weird z-banding and couldn't chase it down. Removed the feet and the banding was gone. I'll suffer through the additional noise to get a better print!
Re: Cant calibrate I3 Prusa Plus
yeah i feel that anti-vibration feet without some kind of damping just moves the mode to another frequency or another direction and any damping is prob accidental to some designs as i doubt an analysis has been done on many of these feet and like you mentioned you can get 'cross-talk' vibration across different axis depending on the setup.
Im having trouble finding a place for the printer in the house and at the moment have settled on leaving it on the dryer in the garage on about 1in thick rubber type mat. Dryer gets used about once a week, but vibration amplitudes seem lower than when printer is in operation. So see how that affects the calibration. I know i had to recalibrate each time i picked the thing up so time will tell how that setup works! Of more concern is the colder temps outside!