Dealing with FINDA Not Triggering on MMU3 - on a filament NOT used in the print
When I first setup my MMU3, I ran into an issue that took several days to track down and resolve. It turned out I had a burr inside the hole one of the bearings for the idler was supposed to fit in. That's my own print, I'm not blaming anyone, just documenting what happened. With the bearing not all the way in, that left the idler almost aligned. It looked aligned - until I used a flashlight and watched the MMU changing filaments. When I saw that misalignment, I fixed the issue in about half an hour and things were working great.
Now I'm running into this:
I started another thread about using a single material mode with the MMU3 and a Mk3.5 a few minutes ago, but this is another issue.
I currently have black PETG in slot 1, white PETG in slot 2, and slots 3-5 are PLA. For my current work, I am using ONLY the PETG in slots 1 and 2. I was trying to use PrusaSlicer to work in a single material mode, so I could print ONLY with the white PETG in slot 2. I'm not sure I did that. (And, as I said, that's another topic on another post.) I'm printing 2 objects, both using the same filament (again, the one in slot 2). I don't see why there would be any need, in the entire print, for a tool change or for unloading or loading new filaments. But, what's even more confusing is that when I hit "RETRY," it is trying to load in slot 5!
It looks to me like I have two problems here:
- Why is it, in a 2 object print, when I've used PrusaSlicer (V. 2.8.0) and specified that both objects use the filament in slot 2, my printer is trying to use the filament in slot 5? (Related: If I've specified ONLY one filament for both objects, why is the printer trying to load or eject any filament at all in the middle of a print?)
- I've looked over the error page for this error. I'll be working through that (I'm noting that this isn't a problem for other slots - only for this one), but are there any suggestions from those who have dealt with this about what to check first and any suggestions beyond those on the error page?
RE: Dealing with FINDA Not Triggering on MMU3 - on a filament NOT used in the print
I don't think this is a resolution, since it's so finicky, but I've found a temporary fix - whether the filaments in slots 4 and 5 load properly has become extremely alignment dependent! If the tubes going into the MMU aren't aligned just right, then those two won't load. (And, yes, I've pulled the filaments out and cut the ends off at slants again, and made sure there are no divots or dents in the filament from the pulleys grinding against them. I've also opened up the MMU and cleaned the pulleys, blew out any debris, and so on.) This is a new development. It wasn't an issue a week ago and it is now.
I have a temporary solution, but I'd like to know what I'm doing or what changed that suddenly makes a perfect tube alignment so important. My best guess is that this is a high humidity climate, so if a filament has been out for a while, even in the tubes, that maybe the humidity is effecting it and that may change how it feeds into the tight area where the idler bearings push against the pulleys. I'd love to hear more if anyone has run into this or what I should do, other than re-aligning the tubes, to create a permanent solution.
This is how it's been set up since I finished installing it:
The PTFE tubes feeding into the MMU have been in this position since I stared using it. Then, while working on it, I took the MMU3 off the frame and set it to the side, where I could see what was going on more easily and so I could clean it out. Testing with the MMU to the side worked fine for loading all filaments. I put it back on, re-tested, and it wouldn't work for 4 & 5. After a few experiments, I found it was positional. Those filaments loaded fine with the MMU to the side, but would not load with it on the printer.
I've had to make an adjustment and both the trouble filaments loaded fine:
For now, this is my solution:
That's with duct tape holding it in place. There's a bit of pull on it from the tubes feeding out of the cartridge/buffer, so one of the first things I'll be printing while it's like this is a bracket to hold the tubes in place. I've found this is quite sensitive to whatever angle or position it's in, so I think I'm going to make a bracket that makes it easy for me to change the position easily if needed. Maybe even something like some kind of simple pegboard design that goes on the plywood and a bracket that plugs into it, so I can change the alignment if needed.
RE: Dealing with FINDA Not Triggering on MMU3 - on a filament NOT used in the print
I get this error the filament gets stuck upstream of the MMU, or it is loading an empty lane of the MMU. I can't explain why it is moving over to lane 5 unless it's doing one of the unexplained remapping FEATURES they added to confuse us all. I seem to remember some talk about lane 5 begin the default path for some feature. I know that is a completely useless comment, but maybe it will invoke a response from someone else who has the answer.
The single mode is so FUN to use that I avoid the frustration completely.
If printing using a 0.4 nozzle, I use the standard MMU profile and just select the filament channel I want.
If printing with any other size nozzle, or if printing more than one object, I preload the filament to the nozzle, and then slice with a standard non-mmu profile. Unlike the single mode, this methods works every time.
I haven't yet taken to time to create my own larger nozzle profiles for using the MMU, but I plan to.
RE: Dealing with FINDA Not Triggering on MMU3 - on a filament NOT used in the print
"After a few experiments, I found it was positional. Those filaments loaded fine with the MMU to the side, but would not load with it on the printer."
The MMU3 eliminated a joint and put the PTFE all the way in. I found it still needs a little longer straight distance to Push the filament in consistently. I used this MMU3 PTFE tube guide. I even doubled the length by scaling Z 200%. There can be a lot of twist in the filament, especially when it gets near the end of a roll.
RE: Dealing with FINDA Not Triggering on MMU3 - on a filament NOT used in the print
I get this error the filament gets stuck upstream of the MMU, or it is loading an empty lane of the MMU. I can't explain why it is moving over to lane 5 unless it's doing one of the unexplained remapping FEATURES they added to confuse us all. I seem to remember some talk about lane 5 begin the default path for some feature. I know that is a completely useless comment, but maybe it will invoke a response from someone else who has the answer.
Not useless - that at least gives me some idea of what's going on and why it might be going to slot 5 when I'm only using slot 2 - and it lets me know it's probably doing a real "thing," and that I'm not crazy thinking that's what's happening. That's a big help to me, mentally!
The single mode is so FUN to use that I avoid the frustration completely.
I saw your post on that in my other thread - I'll reply to that there.
If printing using a 0.4 nozzle, I use the standard MMU profile and just select the filament channel I want.
I would think if I'm using just one filament, that there would be no need to change channels or tools. (I'm using the standard 0.4 nozzle that came with my printer.) That's why it's been so puzzling or confusing to me that it's having problems with something in slot 5. Also worth noting that I'm printing out 2 "T" shaped objects to use to test the fit in square aluminum tubes. The error is about halfway up the objects, so that's another puzzler. I would think, if it were checking other filaments at some point, that'd be at the start or the end, and not in the middle of the print.
"After a few experiments, I found it was positional. Those filaments loaded fine with the MMU to the side, but would not load with it on the printer."
The MMU3 eliminated a joint and put the PTFE all the way in. I found it still needs a little longer straight distance to Push the filament in consistently. I used this MMU3 PTFE tube guide. I even doubled the length by scaling Z 200%. There can be a lot of twist in the filament, especially when it gets near the end of a roll.
Thank you! That not only confirms my findings (always welcome, since, like I mentioned above, it can help just to know it's a real issue and not something I'm causing or messing up on, or just misunderstanding), but it gives me a good solution. So, yes, it is that touchy about the alignment and, yes, there is a fix for it. I'll be printing two versions of this, one normal length, and, like you, one with Z at 200% to make it longer. It's good to know that even if it is an issue, there's a solution!
RE: Dealing with FINDA Not Triggering on MMU3 - on a filament NOT used in the print
The MMU3 eliminated a joint and put the PTFE all the way in. I found it still needs a little longer straight distance to Push the filament in consistently. I used this MMU3 PTFE tube guide. I even doubled the length by scaling Z 200%. There can be a lot of twist in the filament, especially when it gets near the end of a roll.
I downloaded the STL file. I made a 2nd and, instead of just changing the Z axis to 200%, I checked the total length and it's 26mm. I loaded it into Blender (my 3D editor) and extruded the end by 25 mm, so it's basically double length, without changing the ends to make it harder to snap the tubes in. I printed both the original and the longer one and tried the longer one. It helped, some. It didn't work in my preferred printer position, but did work close to that. I snapped the original length one on to the tubes right after it and that helped - still took a bit of jiggling to make it work.
I'm printing out a test part for my current project, but when that's done, now that I have a 1x length and 2X length, I'm going to print out a 3X and 4X as well and check to see if the 3X works. (I think the 4X will make it hard to fit in because it'll use enough tubing it'll make the curves from the buffer cassette a bit tough to do.
RE: Dealing with FINDA Not Triggering on MMU3 - on a filament NOT used in the print
I'm going to provide updates until I feel 100% sure I have a 100% solution.
I printed out longer guides, the 3x and 4x I referred to in the last post:
I put my fingers in there for scale. I created these longer guides in Blender by just stretching the featureless middle part by 25mm for each longer version. I would have liked to have gone with the 4x version, but it looks to me like the distance in between the two ends is so long it's going to be easy for the tubes to flex more than I'd want in that long straight area, so I went with the 3x. It worked with simple tests.
I'd like to do a 4x version with another clip in the middle, like the one on the end, so the filaments are held in place for that long stretch of space. I don't know when I'll have time to do it. (But if the 3x doesn't work, you can bet I'll find time in a hurry to do the 4x with an extra guide!) I suspect the 4x one would eliminate this problem entirely IF it had another pinch point in the middle, or maybe 2 more of them, each 1/3 of the way along.
If the 3x that I'm using works, I won't be adding another post to this thread to address that.