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ssill2
(@ssill2)
Noble Member
not holding out hope on PVA

I've not had good success with PVA.

I was just watching the interface layers go down for the first print and I'm thinking I might have to have less bridging. PVA doesn't bridge well in my experience.  I've never tried to print so much supported material lol.

But maybe I'll try it again with less distance between the supports.

Posted : 02/08/2021 10:59 pm
ssill2
(@ssill2)
Noble Member
Meh

First attempt it great. Running another with improved settings .  I don’t think I purged enough because there’s some contamination of the pla with pva 

Posted : 03/08/2021 12:11 am
ssackett
(@ssackett)
Active Member
Topic starter answered:
Renovating the mmu2

I have just found out about the different varieties of PTFE tubing used with the MMU2 (1.85mm ID inside the extruder and 2 to 3mm from the buffer and a special tube between MMU and extruder), also that there is a special heat brake for the hot end.  I have all that stuff on order and will see if it helps any.  Also I am adding Festo Pneumatic connectors to the input of the MMU.  Seems like Prusa should do a better job documenting things like this.  They must have noticed by now how much trouble people are have getting the MMU to work. 

Posted : 03/08/2021 2:13 am
ssill2
(@ssill2)
Noble Member
Let me know how it goes.

I’m 2mm ID throughout and no issues now

oh and here’s latest with soluble.  Not bad but it could be better.

Posted : 03/08/2021 2:21 am
ssackett
(@ssackett)
Active Member
Topic starter answered:
PTFE tube length

Do you know what length the PTFE tube in the hot end should be?  I have been trimming it to be as long as possible, but it occurs to me that because the tube swells and softens when heated that this might cause it do deform and create a restriction because it has no room to expand.  The other side of the argument is that if the tube is shorter, that it might result in creating a cavity above the heat break that accumulates melted plastic which hardens into a plug when cooled.  So what do you think? 

Posted : 03/08/2021 6:35 pm
ssill2
(@ssill2)
Noble Member
I don't

I've only used the the ones that came with the assembled hot end.  Hang on, I do have a spare assembled hot end for the MK3S+  I can measure.

Here we go

Posted : 03/08/2021 6:49 pm
ssackett
(@ssackett)
Active Member
Topic starter answered:
Chamfer?

Thanks.  From the picture it looks like there's an outside chamfer on one end and an inside chamfer on the other, is this correct and which end is up?

Posted : 03/08/2021 7:26 pm
ssill2
(@ssill2)
Noble Member
correct

rounded(exterior  chamfer)  end goes down. 

Posted : 03/08/2021 7:29 pm
ssill2
(@ssill2)
Noble Member
Soluble success

Pva + pla.

Posted : 03/08/2021 11:55 pm
ssackett
(@ssackett)
Active Member
Topic starter answered:
Nice

What were your parameters and what is the length of the piece?

Posted : 04/08/2021 12:49 am
ssill2
(@ssill2)
Noble Member
Settings

It’s slightly shorter than the diagonal of the plate.  I sliced it with 2.4 prusaslicer.  I can attach .3mf tomorrow if you want 

Posted : 04/08/2021 12:59 am
ssill2
(@ssill2)
Noble Member
Still on plate

Posted : 04/08/2021 1:27 am
ssackett
(@ssackett)
Active Member
Topic starter answered:
File

Yes, I would like to have the 3mf, it will come in handy when I get my MMU running again.

Posted : 04/08/2021 1:36 am
ssill2
(@ssill2)
Noble Member
RE: as requested

Again this is done with PrusaSlicer 2.4.0 as built from master so don't try to open it on 2.3.3.

 

 
I'm about to print another one of these in ziro silver black to test BVOH.
Posted : 04/08/2021 2:31 pm
ssackett
(@ssackett)
Active Member
Topic starter answered:
3MF received

Thanks for the file, please send the BVOH file also once you have success.   BTW: Do you know of any documents that explain what the buttons on the MMU do in reality.  I have never been able to use them successfully in the manner Prusa documents.

Posted : 04/08/2021 3:55 pm
ssill2
(@ssill2)
Noble Member
same file

The file you have should work, just change filament 5 to be verbatim bvoh.

I also change the layer height for this print to .15 from .2.  otherwise the same settings as the PVA one.

The best practical explanation of all the MMU buttons is here

MMU theory of operation

 

Posted : 04/08/2021 3:59 pm
ssackett
(@ssackett)
Active Member
Topic starter answered:
Excellent, Excellent, Excellent

I'm in love again!  All of my questions were answered and some of my suspicions confirmed, I wish I had seen this two years ago it would have saved hours of confusion and many failed prints.

Posted : 04/08/2021 6:37 pm
ssill2
(@ssill2)
Noble Member
if you watch it enough

Stuff starts to make sense after you've watched the MMU in operation as much as I have lol.  but I'm truly excited to see this work for you.  It really is cool to see it work.

Posted : 04/08/2021 6:41 pm
ssill2
(@ssill2)
Noble Member
so far so good

on this bvoh + PLA(Ziro Silver Black)

Posted : 04/08/2021 7:28 pm
ssill2
(@ssill2)
Noble Member
another flawless mmu print

PLA + BVOH.  I'm almost feeling like trying the Aquasys 120 again and see if I have any luck with it.

Posted : 04/08/2021 10:48 pm
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