To see this working, head to your live site.

Edited: Feb 05

Filament stripping at Chameleon gears

I have been working to get my 3D Chameleon working for a few weeks now and have been able to work out all the issues exept one.

After 4-8 color changes a filament will fail to unload. Checking the filament there is a big notch where the chameleon gear grinded away at it.

I thought it was due to loading too far during load, so I tuned that so it doesn't grind the filament at all but feeds consistently still. Probably undershooting load time by a hair.

It kept happening so then I thought the filament must be getting stuck either in the extruder or PTFE opening. I checked the filament and it can easily pass through and is not trapped in the gears when this failure occurs. So I don't think it's a tip shape or unload issue.

I tried a few different slider tensions, but no difference was noticed for this issue. Currently using the default tension, +.25 spacing, for all of them.

It seems to happen sooner with some filaments than others.

My loads and unloads are perfect at this point, but I can't seem to figure this one out.

Any ideas why this might be happening and how to find the culprit?

Edit, more info: This is on my Creality K1 Max. I see the extruder lock arm move a bit (indicating the filament is in the gears) at the same time as hearing the motors stop, so I think my load time is spot on. I have been checking the filament after each unload to see if there is a spot gradually wearing down, but never notice anything. Then out of the blue it just happens. Perhaps when unloading? UPDATE: It seems that the default tip shaping was the issue. For whatever reason it was not consistent and occasionally gave a wide tip that got caught in the PTFE when unloading. I redid my tip-shaping code, and now it is both more conistent and faster.

M83

G92 E0;
G0 E-25 F2000 ; retract a bit, adjust this to tune waste
G90

G0 X295 Y150 F4000 ; move to aux fan COOL DOWN
M106 S255 ; part fan 100%
M106 P2 S255 ; aux fan 100%

M109 S190
G0 24 F1500 ; TIP SHAPING WARM
G0 E-5 F500 ;
G0 E5 F1500 ;
G0 E-2 F500 ;
G0 E2 F1500 ;
G0 E-24 F500 ;

G90
M106 S0 ; part fan off
M106 P2 S0 ; aux fan off
G0 X284 Y293 F4000 ; MOVE TO BUTTON
M109 S200
G92 E0
G0 E-60 F500 ; RETRACT
G92 E0
M107 ;
G91; relative mode
M104 S[temperature];

7 comments

7 Comments

las_vegas

Feb 05

I had this occur when the filament wasn't fully unloaded from the extruder before the Chameleon tried to retract it. Check the Extruder to Hotend measurement.

Edited

Alan

Feb 05

Replying to

yeah I wondered about that too, so my retract move before unload is extra long. defnitely outside the extruder gears by the time it starts pulling it back to the splitter.

I actually think I found the culprit, tip shaping inconsistency. It will make a perfect tip 90% of the time, then out of the blue will make a swollen tip that gets stuck a bit.

I completely re-did the tip shaping, and now I haven't had it chew up my filament at unload (still testing). This tip shaping code seems to be more consistent, and way faster too since it doesn't cool to 150.

I added the tip shaping code as an edit to this post

Edited

Bill

Feb 04

There must be something else happening. It's very unlikely the tension is too high at those settings and distances... in fact, at +.25, thats .5mm farther away on each filament... so 1.0mm extra distance between them. My guess is it might be too far away... which is causing a slip that is grinding it down. If the teeth are firmly gripping the filament, and it's moving, then it won't grind it at all... if anything, it'll push out the PTFE tubes if there is back pressure. Is this a fully assembled unit, or did you print the parts?

Bill

Feb 04

Replying to

When you repring the B and C parts, you should always reprint the A parts in the same orientation. If there are differences in the printer, filament or orientation, that will lead to tolerance differences between the lengths of the parts. I recommend reprinting them as a set to make sure that doesn't happen.

At last print new A parts using the same orientation on the build plate as your previous B/C prints and using the same filament.

One way to check is to look at the old B/C parts and compare their length to the new B/C parts. If they're not identical to .05 mm, then you'll have issues. The distance between the selector and the extruder motor placement within the system is critical. You can see it sometimes if you put it on T1 or T3 and look straight down at the extruder motor... if the distance between the bearings for T0 and T2 are not equal, that's a symptom of their lengths being off.

Bill

Alan

Feb 04

Replying to

I will reprint the whole thing together in the same orientation this evening. I tried the +1.5 tension sliders today and was able to get 10 color changes through a 2 color benchy before it stripped the filament, further than before. IDK if that gives any clues as to what is going on. Also, what are the appropriate F values for the extruder during load?

Edited

Alan

Feb 21

Replying to

Hey Bill, I am getting closer! I have had one successful 2-color print with 0 intervention, then started having chewed filament again....

I think I have found a possible culprit and wanted to run it by you. I see in the profile you have on Printables that the extruder load and unload speeds are F500. Am I correct in thinking this should be the same speed as the Chameleon feeds? 1"/s is exactly F1524, so should I be using this value or F500? I was able to get less chewing up of filament, but now I am thinking it is not handing off properly despite the speeds and feeds being right. Is it possible that the Chameleon is starting to unload slightly before the extruder starts moving? If so, how would I remedy this? Here is my unload and load sections:

G0 Y3 F2000 
G0 E-80 F1524 ; UNLOAD
G4 P17500
G0 Y-3
G4 P400

G0 Y3 F2000 ; 
G4 P17750 ;
G0 E80 F1524 ; LOAD
G0 Y-3 F2400;
G4 P400

edit: I just reprinted A,B and C parts on a different printer, assembled it with the tensioners that came with the Chameleon. Now T1 unloads when T2 loads, and vice versa. T1 gets stuck when unloading still and results in failures... I am starting to get to my limit. I have been working on this for over a month, literally min 6 hours a day and have wasted kilos of filament. The threaded hole where I mounted the Chameleon is completely stripped from constantly removing and rebuilding the whole thing. I have to put a nut on the inside just to keep in secure now. I really hate giving up on things, but this is starting to wear on me. Having thoughts like "should have just got an A1 combo"

Edited