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jacinto.c
(@jacinto-c)
New Member
Problem cut filament

Hi ,

I have some problems with multimaterial for the first print. I installed everything and looks like is working fine. The problem is when try to change the filament. The MMU try to cut the filament and then change to second filament. But the blades doesn't cut and is a problem. The cut is aligned and is fine but the blades in the package (2 blades) 1 used 1 in the installation are very bad. I tried to cut filament with the second blade and is imposible. What is the solution for this?

Posted : 02/11/2018 2:35 pm
Neal
 Neal
(@neal)
Reputable Member
Re: Problem cut filament

As with so many other features lately...turn it off or don't use it...seems to be the answer.

Neal

Posted : 02/11/2018 4:43 pm
Shmuel
(@shmuel)
Active Member
Re: Problem cut filament

I have the same problem. The blade donät cut the filament. And if "switch off this feature" the only solution the I have to think to send it back, because I have other problems with the MMU 2.0

Posted : 03/11/2018 10:56 pm
AbeFM
(@abefm)
Re: Problem cut filament

If you get anyone at PR to care about your problems, let me know.

1) Pull the blade off. That fixed my issue for weeks.
2) Get different firmware that uses the blade.

I've done both, both work. Don't expect a response from Prusa.

I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.

Posted : 05/11/2018 8:35 pm
Shmuel
(@shmuel)
Active Member
Re: Problem cut filament

ok will ask the PR

I have the newest firmware on mz MMU 2.0

But I thought, that I need the blade, if the printer change the color. 😯

Posted : 05/11/2018 8:54 pm
PJR
 PJR
(@pjr)
Moderator
Re: Problem cut filament

The blade is a PITA and if you are running stock firmwares, best to remove it as it can cause jams.

The only reason it is present is to be a work-around for other problems (stringing). It basically cures a symptom and does not solve the actual problem.

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…

Posted : 06/11/2018 12:19 am
AbeFM
(@abefm)
Re: Problem cut filament


The only reason it is present is to be a work-around for other problems (stringing). It basically cures a symptom and does not solve the actual problem.

bingo - it's a patch for something that needs to be working right in the first place. I'd rather take off the bullet proof vest and just stop getting shot at. 🙂 originally I was fantasizing about a cutter that left great tips - but then you'd still end up with grams of filament that you cut off for no reason.

For a while, on stock firmware, I did as you suggested, and ran without a blade. I had great luck with that and would go back if the motion control improves.

I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.

Posted : 06/11/2018 7:52 pm
PJR
 PJR
(@pjr)
Moderator
Re: Problem cut filament


...and would go back if the motion control improves.

[controversial]
But that's the thing. Stock MMU firmware does work (for me). All this nonsense about re-homing and crash sensing, when in fact most Mk3 users are printing with crash detection turned off and do not re-home at all during a print. And yet the print turns out just fine.

Why should there be a need for crash detection and re-homing on the MMU? Only if there is a hardware issue which needs to be corrected. So again, why cure a symptom when the best solution is to solve the problem.

Yes, I know that some of the MMU2 firmware code is "noddy", but it does work for the vast majority of users.
[/controversial]

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…

Posted : 06/11/2018 10:57 pm
AbeFM
(@abefm)
Re: Problem cut filament

I would REALLY like to have a sense of how well it works for how many people. "I saw a bunch of posts that said...." is not a percentage, and it generally over-counts the ones that work.

I never got an explanation or anything to try to fix my ridiculous homing, and I've asked A LOT. I would certainly try things were they presented as options.

I think there's a few hard to detect things ('hidden variables'), so replacing a piece of PTFE helps, but it was really the realignment that took place which fixed it.

That is why it is so UNGODLY frustrating we can't get real interactive conversations about stuff - to see what's an issue and what's a freak occurrence.

The filament retraction seemed to be a huge issue. The matching the motor speeds was a big one.

What I MEAN by motion control is coming up in a repeatable state (EVERY reset should leave EVERY part of the system in a known state) and some useful things like making it possible to continue a print once you have fixed an issue - getting coordination between mk3 and MMU. Allowing you to load or unload the print head. Obviously setting the stall currents up, not over-retracting filament (which then skips the drum), not overheating the motors which softens the inner drum and gets it to slip on the stepper, etc. All firmware fixes, I think.

If you get a jam and have to reset (because the drum isn't aligned or there's a jam) you can get as far as pre-loading the MMU with clean filament, but all you can do is tell the printer to "change filament" and watch in helpless horror as ten lines of missing or wrong filament are extruded.

Frankly, since there's no data gathering from the public, I wish they'd kept the device, GOT IT WORKING, and then shipped me something good. It is cool there's upgraded hardware to print and firmware to flash from the community, but then everyone's got a different version and we can't talk to each other. It's a cool idea if you a professor, but not so good if you're selling a standard product.

All that said, it would be awesome if we could figure out why some work and some don't.

I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.

Posted : 07/11/2018 12:46 am
jason.k24
(@jason-k24)
Eminent Member
Re: Problem cut filament

My blade actually hit my machine last night when the selector was scrolling during a reboot and the blade popped out the side. I just completely removed it.

It has done nothing the entire time its been installed and theres no way it will ever cut filament with the way its installed. And even if it did i dont see how the cut filament would properly fall out anywhere vs just getting stuck in the FINDA area before the next color is selected. Just a worthless option IMO.

With that being said my machine in general is working great...even single color prints some how seem better with the MMU controlling it.

Posted : 07/11/2018 3:21 pm
Shmuel
(@shmuel)
Active Member
Re: Problem cut filament

As I can see, tha distance between the opening from where the filament is coming until the blade is bigger than the diameter of the filament.
From mz understaning, the distance should be almost zero, that ît can cut.

Posted : 10/11/2018 6:43 pm
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