What is the best spool holder alternative?  

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david.f42
(@david-f42)
Honorable Member

The problem I'm having with the Prusa I3 MK3 spool holder that came with the kit is that if I use gcode to raise the print head more than a couple inches, the spool can become partially unwound (or maybe "unlooped" or unravel would be the right word). Is there a spool holder where that doesn't happen?

Posted : 10/06/2018 8:55 am
joan.t
(@joantabb)
Veteran Member Moderator

Hi David,

you could adapt this idea
for my MMU, the filament reels are on a shelf,
there are 100mm stubs if PTFE coming thru the shelf in line with the spool holder where the filament runs off the spool,

the filament is then taken via ptfe tube to the extruder,

thete is no reason why this could not be done to the mk3 extruder...

benefits, spool holder not on top of frame, and raising the extruder will not spill filament off roll

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 10/06/2018 9:26 am
ram64
(@ram64)
Eminent Member

I am using the Spannerhands Spool Holder and it works well so far. It takes a while to print all the parts and you need some extra things (screws, threaded rod, bearings, PTFE tube and a pneumatic coupler). The main reason I stuck with it is the fact that it's enclosed and you can put some desiccant inside it to keep your filament dry, therefore no need to pack it up back in a dry box if I don't use it for some time. Here are some photos of mine, ignore the print quality, the issue was the poor filament used (tried to smooth the surface by sanding it but gave up as it would have taken too much time).

...
Posted : 10/06/2018 10:24 am
david.f42
(@david-f42)
Honorable Member

I'm not entirely sure, but maybe this thingiverse thing will do it:

https://www.thingiverse.com/make:494591
It appears to claim that it maintains tension. Looks like maybe it does.

I suppose this filament guide might also help: https://www.thingiverse.com/thing:1940114

Posted : 10/06/2018 3:32 pm
thomas.s37
(@thomas-s37)
Eminent Member

Hi David,

the one you linked from thingiverse is pretty good. It was under the first items I printed with the MK3 to replace the Prusa one. When you print it in PLA however make sure not to drop it to the floor 🙂 the screw does break easily. I tried.... . Otherwise it runs with my printer for 5 month already.

The attachment mechanic from the spool holder too is better than Prusas. (I.e. easier to attach and unattach)

Still you asked for loosing tension/unwinding:
- the spool holder is defininatly better than the prusa one in regards that only as much filament as needed is unwound.
- however the spool holder does not wind the filament again if you move the extruder to the top, if you do think it does. The filament will still get a bit more loose on the spool.

Best regards,
Thomas

Posted : 11/06/2018 12:00 am
david.f42
(@david-f42)
Honorable Member


- however the spool holder does not wind the filament again if you move the extruder to the top, if you do think it does.

Oh no! I don't mind the filament being loose, but if it slips off (kinda uncoils, if you know what I mean) from the spool when the print head is raised high, then that's a deal breaker. Does it?

Posted : 11/06/2018 4:32 am
Steve_AU
(@stephen-p14)
Trusted Member

+1 on the filament guide above, I've been using these (tush++):

https://www.thingiverse.com/thing:2451368

Does require 4x 608 bearings per set, but they are cheap.

My printer is in an enclosure (so it sits above with a hole through te top to feed the filament through). If the filament is sitting behind, you need to raise it up to the same height as the top of the printer.

Posted : 11/06/2018 12:32 pm
Bigdogbro1
(@bigdogbro1)
Estimable Member

This works the best for me.

https://www.thingiverse.com/thing:2855594

MK3 Kit, Designed, built 4x4 CNC Plasma Cutting Table, Motorcycles Bigdogbro's Adventures
http://www.youtube.com/channel/UC5djrxBeeOKB9_6rHnn6G8A...
Posted : 11/06/2018 2:16 pm
thomas.s37
(@thomas-s37)
Eminent Member



- however the spool holder does not wind the filament again if you move the extruder to the top, if you do think it does.

Oh no! I don't mind the filament being loose, but if it slips off (kinda uncoils, if you know what I mean) from the spool when the print head is raised high, then that's a deal breaker. Does it?

Well, I am still not sure if I understand you correctly. The filament will a bit get loose and get a bit uncoiled because the spool holder does not move backwards since no force is applied in this direction. It did not slip from the spool. And I had no problem with the filament getting a bit more loose because next print it will get tighty wrapped again :). I think you have to try.

Regarding stephen.p14's suggestion, I personally couldn't work with these simple ones because they did fall appart into their 2 pieces when I assembled them. So you might need the grid support which is in stephen.p14's link as without it just did not - in my case - have the strength to stay assembled.

There is still one better holder from my point of view, which is this one:
https://www.thingiverse.com/thing:2809118
The benefit to the one above is:
- that you wll not have to reposition one of the spool holder arms due to a smaller or wider filament spool. Since the has a two ful barells.
- fewer parts to print and to assemble (general better construction from my PoV)

The drawback at the moment is, and that is why I am not using it at the moment - even so I have printed it - is that the fixture to the Prusa3D frame lets the filament spool sit too far behind the frame. This causes the filament, when the filament spool radius is getting smaller over use time, to hit/scratch on the frame which I do not think is good. However! I am working on that solution today by designing an alternative first part. I will link the addon here if you are interested once it works.

Posted : 11/06/2018 6:28 pm
david.f42
(@david-f42)
Honorable Member


It did not slip from the spool.

Ah, good, that's all I care about. Slipping off the spool is what I'm trying to avoid, and why I don't like the Prusa spool holder that came with the kit.


I will link the addon here if you are interested once it works.

I'm interested!

Posted : 11/06/2018 6:36 pm
thomas.s37
(@thomas-s37)
Eminent Member

Here you go!
Print everything from here:
https://www.thingiverse.com/thing:2809118
except the attachments to the MK3 frame.

Replace them by the version as found in the attached .zip file.

See the photos attached.

I basically combined the - better - snap on mechanic of https://www.thingiverse.com/make:494591 with the https://www.thingiverse.com/thing:2809118 . And repositioned where the spool is in order to have the filament always in front of the frame.

Have fun!

(If you are a perfectionist: You might notice that the "ball bearing circle cutout / the large empty circle" from my addon does not exactly match with the one of https://www.thingiverse.com/thing:2809118 . It looks a bit odd if you notice it 🙂 . I missed during design that the circle is not in line by some mm with the other circles. DAMN! However can't fix this now. And since it works not that much desire to rework it :).

If you fix it, the construction data is here: https://cad.onshape.com/documents/d9bf0e49ca3f756fee31c2ee/w/9be8f3bbcf87d8e62ab7875b/e/23fd5a9e110be5d9e257bcb7
)

Regarding printout, I did use the following settings in Prusa Control:
Prusa PETG
0.2mm layer height (FAST)
0.4mm nozzle
30% infill (DENSE)
Support None, Brim Off.

Took about 2hours to print in silent mode.
About 6m of filament according to the software.

Keep in mind too that the general https://www.thingiverse.com/thing:2809118 is made from tight fit parts. You might need a file to get the parts together.

Posted : 12/06/2018 12:48 am
david.f42
(@david-f42)
Honorable Member

Thomas,

I gather the entire thing literally just snaps together? No glue, screws, or bolts?

I'm printing it now using a PLA+. I may solvent weld it just to be sure....

Not sure if it will be needed, but I'm printing this filament guide anyway just in case: https://www.thingiverse.com/thing:1940114

Posted : 12/06/2018 3:52 am
thomas.s37
(@thomas-s37)
Eminent Member

Hi David,

yes no screws,glue, bolts. It just fits into each other and holds by friction / pressure. Depending on your quality of printouts (dimension accuracy you might need to work a bit on the surfaces so they do actually fit into each other if they do not in the first place. I really had trouble with the rectangular bridging element but eventually it did fit in - and I assume I will never be able to separate these pieces again 🙂 ).

The holding by friction/pressure however is too a reason - from my side of view - for the use of PET. Since PET is a bit flexible while PLA is hard/brittle and might break when pushing the parts together. So if you do the PLA version I would like to know how it turned out. I recommend PETG.

Regarding the filament guide. I did never need it, further if the filament would get on its corners it would introduce another bend and somehow I don't know what issue the guide solves. But just my opinion.

Best regards,
Thomas

Posted : 12/06/2018 6:48 pm
david.f42
(@david-f42)
Honorable Member


...So if you do the PLA version I would like to know how it turned out. I recommend PETG.

Yes, I did print it in PLA+, but you are right: too brittle. I broke off one of the axils trying to fit the bearing on. In retrospect, if something is snap together, it is just asking to be done in PETG. So, I'm re-printing it in PETG now.

Posted : 12/06/2018 7:20 pm
thomas.f17
(@thomas-f17)
Eminent Member

I haven't needed the 'Under-bearing' type of spool holder since I'm not too unhappy with Prusa's Mk3 spool holder but I feel it needs support from the other side of the spool, especially when heavy reels are used. There are a few designs out there but I didn't see one that kept the best features of the existing holder so I came up with this https://www.thingiverse.com/thing:3247999 .

This two part design is simple and fits the standard spool holder, which is not modified in any way.

The shape of the support arm is taken straight from Prusa's spool holder (hope you don't mind Joseph) and trimmed both sides. Also, the detent that locks the arm to the frame is removed so it goes on the frame easily (don't worry it won't slip off). I added a bayonet hole for the twist pin - a removable pin that locates into the center hole of the standard spool holder shaft and twists 90 degrees to lock into the support arm.

This spool holder support can be added or removed whilst printing without risking vibrations, yet it is secure and simple.

I may have over-engineered the parts by using PET for both items and fitting a metal screw (#6 csk x 1.5" with locknut) through the centre of the pin, to ensure nothing will ever break and drop on my nice printer. One less thing to worry about!

Posted : 30/11/2018 2:24 pm
Snardo
(@snardo)
Eminent Member

Does anyone have a good solution for a spool holder that sits next to the printer rather than mounted to the top?

Posted : 11/12/2018 9:56 pm
edward.c6
(@edward-c6)
Reputable Member


Does anyone have a good solution for a spool holder that sits next to the printer rather than mounted to the top?

This is the one I use...

https://www.thingiverse.com/thing:3053872

Posted : 12/12/2018 12:24 am
clay.h4
(@clay-h4)
New Member


This is the one I use...

https://www.thingiverse.com/thing:3053872

I like this simple design. How do you guide the filament up and over the frame into the extruder?

Posted : 24/02/2019 2:24 am
vintagepc
(@vintagepc)
Noble Member

My own setup:

Mash-up of:

https://www.thingiverse.com/thing:508896
https://www.thingiverse.com/thing:1754587

and a custom bracket I made to bolt it to the back of the z=top with some longer screws. I made the bracket after finding out the 6mm frame adapter is more than likely to kill your filament sensor connector if you do anything at all that makes the printer move to a high Z height.

Posted : 24/02/2019 2:33 am
edward.c6
(@edward-c6)
Reputable Member



This is the one I use...

https://www.thingiverse.com/thing:3053872

I like this simple design. How do you guide the filament up and over the frame into the extruder?

I use the R1 version of this, https://www.thingiverse.com/thing:2943445/files so there's still a bearing used, but it's mainly to keep the filament moving smoothly...

Posted : 24/02/2019 1:40 pm
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