X / Y 90º Perpendicular Hell
Just finished my MK2 and failed the autohome check. I needed to adjust the x / y frame alignment to get the probe centered. This was very very difficult. I needed to loosen ALL the bolts on the M10 threaded rods as the psu saddle acts as a another connection point between both frames. It took me 3 hours to get it right. Of course the two axis are no longer perpendicular and I am unable to get them at 90º again. Also, the X frame slid down and off the M10 bolts. Which forced me to start in the middle again. Then after all is said and down, the Y rails are no longer parallel and the X and Y fell out of 90º.
I am rather frustrated. I am actually thinking about abandoning the project at this point but before I do, I wanted to asked if there was a special technique for 90º aligning the X with the Y without stomping on all the other calibration points? It seems like everytime I fix one calibration issue, I create another one. I have been at this all day fussing with the M10 bolts. I think I could have built another MK2 at this point.
Please help.
Thank you
Jordan
Re: X / Y 90º Perpendicular Hell
I just assembled MK2 and also was fighting with Y-axis, to be parallelly with X. The calibration was successful, but with comment that axis are not perfectly perpendicular and also the front point was little bit to forward.
So I disconnected and tried to play with M10 nuts. It was not getting better, when playing one nut by one.
Finally what helped me was to loosen them all on the Y axis, loosen them a lot to create some space (meaning just those M10). Also those holding the frame (be carefull, prevent it falling down). I looked from the top finding the parallel with the lines on the bed. When it was good, starting by hand to tighten the nuts to keep the position and finally with the wrench. Then make sure that the distance between the frame and the back side printed part is still 100mm. Adjust it if necessary, but moving the frame same way on both sides M10 should not destroy the leveling.
And maybe before playing with the Y-axis M10 nuts, check the distance between both Y-axis rods. Distance on the front should be same as distance on the back (about 17 cm taken from the middle rod, but could be different for you). If the distance is different front/back, loosen the M8 nuts to make it.
This made me the "perfect" calibration next time.
One more comment. First time I set the position of the PINDA probe as described. But it was too high for me, the probe does not react to the bed from this high and nozzle pushes the bed. I have to go a little bit lower with the PINDA. As a check, PINDA red led gooes off when probe is near enough to bed (or any metal object).
Do not loose you faith 🙂
Sorry if the expressions are not as in manual, I made with czech version.
Miloš.
Re: X / Y 90º Perpendicular Hell
I spent another hour on it last night and got the probe a little closer to the the center of the circle. Part of it was still a bit out of the circle, and the x rods were not perfectly parallel with the bed lines, but I attempted to calibrate anyway. Everything seemed to be going ok but during the far right back calibration point the nozzle touched the bed. 😡
So I pushed the the corners down on the Y frame, tightened the back right mount point (heated bed), and made the probe a little lower. Calibration failed. "Check manual"
Made the probe just a half a turn higher, ran the calibration and it passed. The nozzle didn't touch the bed at all. Did some fine tuning of first layer with a live Z height adjustment but chickened out before the filament line got perfect. I was soo afraid of damaging the bed. Plus I am very less than confident the bed isn't higher in random places.
So I printed the tree frog and it came out pretty good!
But you can see that the first layer needs some love...
So what I am going to do now is perfectly perpendicular the X and Y, adjust the M8 threaded rods to get the two Y smooth rods parallel, readjust the belts, and the pulleys, And ensure all 4 corners are down and level. Then I am going to recalibrate, and go around and manually check (by moving the steppers via the lcd) the clearance between the hot end and the bed. Then I will turn the first layer height.
Some things I wish I had were:
• Recommended distance between Y smooth rods
• Recommended distance between all printed parts on Y frame (inside and out)
• Something more than just an visual alignment of the probe to the wire holder, I see some folks use a dime to check the distance
• Allowable distance tolerances between parts
• Easier way to fine tune the perpendicularness of the X to Y.. like a little gap screw under the frame I can turn to move it a max of 1 mm?
Re: X / Y 90º Perpendicular Hell
See this post: http://shop.prusa3d.com/forum/improvements-f14/mk2-alignment-sticks-t1579-s20.html#p18438
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: X / Y 90º Perpendicular Hell
This is EXACTLY what I was looking for!
Thank you!
Re: X / Y 90º Perpendicular Hell
Wow! That should have been somewhere in the manual - that came with my kit and on the online instructions too.
The big weakness with this Prusa i3 is indeed that without a jig, it is extremely difficult to get it square. For $10 more, print me a jig that I can slot the whole base unit and vertical frame into.
As soon as I get my printer to the point where it works, I'll draw something up for that very purpose. Right now, I have been suffering. There are some key "gotchas" in the construction. For example, if the 10mm rods are too deep into the vertical frame slots, the cap screws that secure the bed to the frame will bind on the frame! Of course, I didn't see that and during calibration the nozzle went down on the bed and messed up the plastic coating on the bed. This is because when the PINDA probe cannot find the calibration point, the software appears to lower the head down further in an attempt to try and locate it (by being closer to the bed). Unfortunately, at this point in the calibration the software doesn't know where the Z axis end point is with respect to the bed, so it will happily lower the nozzle all the way down thus destroying the coating (PEI coating I think it is).
I'm still hopeful that it will turn out alright. Actually, I just got a message that, "X/Y axes are perpendicular. Congratulations!"
Incidentally, I didn't see anything anywhere about the PINDA LED until this message - but you have to be looking down at it to see the red LED.
Now, I have to figure out what to do with the damaged bed....
Chris
Re: X / Y 90º Perpendicular Hell
For $10 more, print me a jig that I can slot the whole base unit and vertical frame into.
I would pay an extra 50 for that... honestly. And what gives! How can that schematic not be in the instructions!!! I think it took me around 20 hours to build my printer... about 12 of them was on the Y frame fussing with the M10 bolts. And it still isn't right! I am going to take this diagram and my extra large calibers and go around the whole Y frame again. I am also going to loosen and retighten all the mounts for the bed, and the redo the Y belt.
Chris, how badly is your bed damaged? Can you post a picture?
Re: X / Y 90º Perpendicular Hell
Update:
So I took that diagram and went around with some large calipers and checked and fixed every single length on the Y frame. The X and Y where perfectly parallel, no adjustments needed. The very first XYZ calibration passed. I only needed to tune the first layer z by -.400mu.
Again, how is a diagram like that not included in the assembly instructions?
Can we at least pin that post? Moderator?