Toolchange reliability  

RE:

I did a factory reset. During the parking place calibration I found one of the parking places were loose! Turned all had started to loosen.

continued to calibrate and now I get a fail on the 5th extruders sensor calibration.

So after two months of brilliant printing my XL is now a bit of a mess.

RE: Toolchange reliability

FWIW… the problem was the side filament sensor. The stupid little ball was stuck in the on position.

Theres a LOT that can go wrong on this machine!

RE: Toolchange reliability

Posted by: @tobycwood

FWIW… the problem was the side filament sensor. The stupid little ball was stuck in the on position.

Theres a LOT that can go wrong on this machine!

I have been bypassing the side filament sensor for a while now. I have a new sensor that I ordered and will mod it after the first of the year. I think it is to stiff and will do magnets in the new one instead of springs. Still thinking about how to handle that ballbearing.

RE: Toolchange reliability

Please post your upgrade! The whole sprung ball bearing sensor design is kinda lame.

RE:

Is this a metal ball? For the MMU there are some mods using a magnet to prevent the filament sensor ball from getting stuck in the on position. Maybe that is an option here too? Or maybe things are too different in the XL, if it using a spring in stock. 

RE:

because of the design of the tool docks using 1 bolt and the machining on the CNC dock not being right to properly lock into the channel there can be lots of movement

and if you don't tighten the bolt well the machine will vibrate them loose over time or they can suddenly pop into a different position and that causes the tool change to fail.

i'm using a bubble leveler now when checking my docks i try to keep them all level side to side and front to back. you can put a leveler on the machined surface to get a reading. next i have not done it yet but i'm thinking to add thread lock(removable) to the bolts that hold the docks to the channel bracket.

i will highly recommend a high quality very long 2.5MM allen screw driver which will allow you to crank down on those bolts. however be careful you can strip out the inserted bracket if really cranking on it.

i found the docks loosening over time and not having a 3 point type of securement a big issue. just adds to the frustration of the XL   

RE: Toolchange reliability

Yeah..l I agree. One bolt is not enough, but the design did not leave them much room for more. The overall printer should have been a bit wider to allow for this.

Im also thinking of a light thread locking material. 
The reset forced me into a full calibration. A major pita, but it also made me look carefully across all aspects of the system and I found the items that needed help.

RE: Toolchange reliability

Interesting,  yesterday I noticed a slight sound that happened during tool changes while I was doing some test prints.   as you guys have said it seemed like something loosened up.   I reran the dock calibration, and everything was fine.   it's something I'll definitely keep an eye on also.

RE:

check to see how level your docks are. if you have a bubble leveler place it on the machined surfaces of the docks, check side to side deflection and front to back.

you can also try to wiggle it with your hands, if it moves with your hand then its gotten loose again.

if one dock is pushed forward or backward enough it can cause the locking pins to not fully close and it might lead to tool error. you can also use a straight edge across all the tools and see how defected they are from each other.

when the docks are level the tool changes are quiet. when something is out of wack you start hearing snapping sounds because the locking pins are fighting to pull the tool off the magnets on the dock.

when the docks are all pretty level then all the 3d printed pieces (the ones you have to loosen when you run dock calibration) will all be parallel with he machined edges. that tells you they are pretty straight if you see a dock where the 3d printed pieces are hanging over the side or look crooked then that dock should be straightened and dock calibration redone.

RE: Toolchange reliability

yeah, I'll check mine in a bit.  the docks are one of the few things I had to assemble, since I bought mine fully-assembled, and I was pretty sure to to tighten but I'm going to check them again.  I'll also check the level and if they wobble at all.   For me what loosened was the docking pins.   I hope the docks themselves haven't loosened since it means I'll have to lift the enclosure off to tighten.

RE: Toolchange reliability

i bought my machine the same way.

i had a set of hardened machine tool Allen screw drivers with long tool ends and i used that in place of the cheap 2.5mm wrench from prusa so i could crank on those bolts.

RE: Toolchange reliability

Yeah I recall following the directions and it said something to the effect of "very tight" which I took to heart.   Most places they say "don't over-tighten"  but that one place they were sure to say to make them very tight. haha, I feel like we are just another round of beta testing haha.

RE: Toolchange reliability

I just tried to jiggle the docks, they are solid in place.   I didn't put a level on them but they are solid.  I'm definitely going to be listening the next time I print to see if anything sounds off.  I think in my case it was just not having tightened the docking pins enough on one of the extruders.

RE: Toolchange reliability

you can also place a straight edge and see if any of the docks is very out of spec from the others. just pop off the nexttruders and place them each on the bed on top of some cardboard so you can access the docks directly.

RE: Toolchange reliability

so now that I'm doing more with extruders 4 and 5 I'm definitely noticing that when it docks E1 and moves all the way to E5 it sounds like it touches of the ones in the middle.   today I'm going to take the back pane off the enclosure and try some tightening and reseating.

RE: Toolchange reliability

I thought this video was interesting.

RE: Toolchange reliability

Interesting!   I'm going to look in to that today.    thanks!

Posted by: @mme

I thought this video was interesting.

RE: Toolchange reliability

I just completely reseated all my docks and redid calibration.   The pcb's on my extruders where the tool interlock happens don't have the kind of play his did.  They are torked on there pretty solid.  I don't have the banding issues he did in the vid.  so I'm not going to install that bumper since, right now, I don't think it's needed, but I'll keep an eye out.  I had to modify the enclosure joint pieces slightly since I think they were interfering with the dock parts.  I'll do some prints and see how this all works.  Thanks again for posting that vid I think it will be helpful for others having issues.

RE: Toolchange reliability

Interesting vid. Unfortunately the solution they came up with is a bandaid and it does not really solve the actual problem of dock calibration. A problem that Prusa would actually see for themselves if they had shipped with the extruders installed and had performed an actual full system test before shipping.

Getting back to the OP…

After recalibration all was well and perfect again, until it wasn’t! The next morning when trying to pickup  tool#2 the machine simply rebooted itself. It worked fine on all the other tools but when I try to pickup #2 it simply crashed. Looking closer, the pins were no longer aligning to the sliding locking bars and the system detected the stepper stalls. Why it just reboots is obviously a fw bug. The dock is solid. No movement at all.  Currently looking at realigning. The only thing that’s varying are the ambient temperatures.