Josef talks about Multiextrusion and more

Prusa i3 printer discussion...the official one from Josef Prusa
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Blizz
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Re: Josef talks about Multiextrusion and more

Post by Blizz » May 29th, 2017, 4:55 pm

I can confirm the bag of Haribo, received the kit today. Bit scared about the tons of components :)

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Meduza
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Re: Josef talks about Multiextrusion and more

Post by Meduza » May 29th, 2017, 8:02 pm

LePaul wrote:I guess I like his open-ness about what he is working on.

Versus selling a printer, when you know you are releasing a new one the next day (i.e. Ultimaker) :)

I think when you help your customers understand what you are working on, that helps build excitement.
Prusa has the luxury of having a huge pile of demand and backorders, and they still only do direct sales... Also remember that they have only shown work on upgrades, not on any new printer.

Ultimaker is in another place, if they would be telling the public that they were to release a new printer in six months or so that would replace a current model, they would effectively be killing 70% of the sales or so of the current model during the next few months for all of their resellers around the world...

I believe something in between would be nice, a bit more openness without sacrificing business.

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ivan.akapulko
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Re: Josef talks about Multiextrusion and more

Post by ivan.akapulko » May 30th, 2017, 4:26 pm

LePaul wrote:I guess I like his open-ness about what he is working on.

Versus selling a printer, when you know you are releasing a new one the next day (i.e. Ultimaker) :)

I think when you help your customers understand what you are working on, that helps build excitement.
It looks strange, becose i remember many people on umforum, who buy UM2+ just in couple days before anounce UM3. They was really unhappy. Why not to propose to customer wait couple days or pay difference in price and send a brand new printer? Sure, all cases was solved by helpdesk after. But why do unnecessary work, if it could have been prevented by simply asking a person to take a timeout for a couple of days before buying.

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Re: Josef talks about Multiextrusion and more

Post by LePaul » May 30th, 2017, 4:52 pm

Oh don't get me started. I missed out on the UM2 by two weeks. And no returns on UMO kit. I was not impressed.

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Re: Josef talks about Multiextrusion and more

Post by ivan.akapulko » May 30th, 2017, 4:55 pm

Looks like not all cases was solved. Sorry if I stepped on a sore spot, man.

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Re: Josef talks about Multiextrusion and more

Post by LePaul » May 30th, 2017, 5:18 pm

No worries. I eventually got one :-P

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Blizz
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Re: Josef talks about Multiextrusion and more

Post by Blizz » August 6th, 2017, 4:00 am

So yesterday I installed the MM upgrade.
I have to say, I'm somewhat disappointed.

The printed part quality for the extruder housing was pretty poor in my kit. The part seems to have released from the bed during printing and was somewhat deformed but they still decided to ship it. I can't securely tighten the pinda because of it, and the multiplexer screw is way to hard to get in. Not really something I'm used to from Prusa. After checking the actual channels for the filament and deeming those OK, I decided to use the piece, planning on printing a replacement ASAP.

First really annoying issue: the holes for the square nuts that hold the extruder idlers spring-fitted screws are at the bottom. So if something happens and you have to remove the screws to get to the filament, the nuts will fall out. It's not just a matter of taping the holes shut, they actually need to sit about 1mm farther in the hole. Basically you'll have to put the printer on its side to get them re-fitted (if you manage to find them after they fall out).

Also the extruders are so close together that it's nearly impossible to get into the housing of the 2 in the middle without having to move them further apart (which means cutting the zip ties and messing up the cables).

I've actually had to re-open all 4 extruders because they were all grinding filament. Turns out you do have to make sure that there is plenty of pressure on the springs so that it will correctly guide the filament into the bowden. If not, the filament will miss the hole and get squashed.
Positive note: Every extruder actually has 2 grubs geared together, so the filament is gripped the entire way around. Very good system.

After that: Printing... Turns out I can't.
Apparently - I've searched but haven't found anything - there isn't a special system in place to load filaments so the printer knows how far in the bowden every one sits. Loading is done by feeding the filament in the extruder (with it turning at a slow pace), then pressing the button and then the speed will increase and it will fast feed it into the bowden tube. Obviously it's impossible to press that button at exactly the same filament load, so they won't all sit the same distance in the bowden.

The multiplexer itself has no logics, it's just a 4-to-1 channel. This means that "first come, first serve" is applicable. In my case, the 2nd filament managed to get a little further in, into the top of the extruder. This effectively blocked the first filament (which the print started with) from entering the hotend. After the extruder started skipping I had to unmount the multiplexer to see what was going on.

All other attempts so far have been pretty similar.
I can't help but think that this will remain a huge problem, since there's no functionality in the firmware that indicates that at any given time it knows which extruder is "loaded". When you use the firmware to change the active extruder, it does nothing apart from selecting the new one to receive commands. No retracting, no loading.

It's safe to say that at this point, I'm pretty sick of the entire thing and am seriously considering to "downgrade" back to a simple MK2S.
Either that or someone will come and tell me how stupid I am and how simple everything is with some guide on how to correctly load filament.
For now anyway, the printer is going back to the attic as I don't want to see it anymore.

Couple pictures for your viewing pleasure:
collage.jpg

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Re: Josef talks about Multiextrusion and more

Post by LePaul » August 6th, 2017, 12:26 pm

Wow that's too bad that mod has been such a hassle

I would really expect better from Prusa

I would still love to try out one of those Prusa printers but I can tell you, the CR-10 is half the price and can do so many things better.

It's kind of interesting, a year ago his $700 printer was all the rage for it's amazing print quality. A year later, we have the CR-10 for $400 doing the same but vastly bigger volume. I wonder what the coming year will bring!

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Re: Josef talks about Multiextrusion and more

Post by nilrog » August 9th, 2017, 6:18 am

Blizz wrote:
August 6th, 2017, 4:00 am
Positive note: Every extruder actually has 2 grubs geared together, so the filament is gripped the entire way around. Very good system.
Yup, those Bondtech gears do know how to handle your filament...just like you need to handle a girl :lol:

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Re: Josef talks about Multiextrusion and more

Post by LePaul » December 7th, 2017, 11:41 am

Did you see this?


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