MMU upgrade suggestions  

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merrill.a
(@merrill-a)
Trusted Member

How about using a curved blade in the cutter since I have heard of the blade cutting one way but catching on the back stroke. A curved blade would cut both ways.

Saw some YouTube on a problem of a thin wall on the carriage where it uses 2 screws to lock on to the motor shaft. I took the Prusa carriage file and thickened the wall between the screw head and the square nut. Then used a 3mmx10mm button head screw(s) for tightening. This increases the space between the square nut and the screw head by over a mm. I can post the mod if anyone interested. 

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Posted : 08/09/2020 8:41 pm
Karl Herbert
(@karl-herbert)
Famed Member
Posted by: @merrill-a

How about using a curved blade in the cutter since I have heard of the blade cutting one way but catching on the back stroke. A curved blade would cut both ways.

Saw some YouTube on a problem of a thin wall on the carriage where it uses 2 screws to lock on to the motor shaft. I took the Prusa carriage file and thickened the wall between the screw head and the square nut. Then used a 3mmx10mm button head screw(s) for tightening. This increases the space between the square nut and the screw head by over a mm. I can post the mod if anyone interested. 

I installed a double blade at the selector of the MMU2, which cuts in both directions.
But I would be interested in your solution. Could you upload data, photos or a link?
Thanks!

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 08/09/2020 8:58 pm
merrill.a
(@merrill-a)
Trusted Member

Two items answers:

Still looking for a curved blade but may have to modify one of my tool cutter blades (not Prusa).

I used the term "carriage" in my second comment. Should have been "idler".

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Posted : 09/09/2020 5:28 pm
merrill.a
(@merrill-a)
Trusted Member

In response to what I can post: I have an STL file of the modified Idler that I can post. The screws I used are 3x10mm BUTTON heads.

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Posted : 09/09/2020 5:30 pm
Karl Herbert
(@karl-herbert)
Famed Member

@merrill-a

2 Prusa blades similar to this: https://www.amazon.de/gp/product/B000TK4HTQ/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 09/09/2020 7:37 pm
merrill.a
(@merrill-a)
Trusted Member

The link goes to the same one edge blade used by PRUSA. I had thought of taking one and trying to sharpen it on the second side. I will do some research here in the states on Amazon USA. Thanks for the suggestion.

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Posted : 09/09/2020 10:04 pm
merrill.a
(@merrill-a)
Trusted Member

These blades come so you can break off one at a time or two, etc. . Thought I could break off one and put it in normally and then break off another and reverse it but that will not work unless I modify the whole assembly. Is there a mod to do this? The picture looks like a modified assembly.

This post was modified 1 month ago by merrill.a
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Posted : 20/09/2020 8:13 pm
Karl Herbert
(@karl-herbert)
Famed Member

@merrill-a

Yes, this is a modified version built after this model: https://grabcad.com/library/mmu2-mmu2s-multi-material-unit-v2-3-1

You must print the selector, the blade holder and the front PTFE holder according to this model. Please read the instructions there.

 
Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 20/09/2020 10:01 pm
merrill.a
(@merrill-a)
Trusted Member

Thanks, downloaded the files and will review. I did a MOD of the E-2 selector to give clean-out access to the filimant area under the ball and also to use two box cutter blades  (similar to the picture). The only problem I found was that the blades tended to slip/drop down even with a tight cap pressing down on them. I used some Bordens glue stick to hold them in place and that seems to work. Will be interested in the solution used in the mod you listed.

Again, thanks and will update as necessary.

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Posted : 22/09/2020 10:57 pm
merrill.a
(@merrill-a)
Trusted Member

After downloading the stl files I really have more questions than answers. Are there any instructions on assembly as the parts seem to have modifications that need clearification. Example is the screws that lock the idler to the motor shaft.

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Posted : 23/09/2020 2:26 am
Karl Herbert
(@karl-herbert)
Famed Member

@merrill-a

No, unfortunately there are no instructions for the assembly. But this works similar to the Prusa instructions, only some parts have been modified. On the Idler stepper a steel insert was used, because it has often happened that the original construction loosened the connection when too much heat was applied.
What also changed on the selector is that a magnet (10x6x2) was inserted near the steel ball. The blades can be glued together, but they hold their position even without glue. That also depends on how accurately and precise the parts are printed.

Translated with www.DeepL.com/Translator (free version)

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 23/09/2020 8:07 am
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