Tension-Free Filament Feed?  

RE: Tension-Free Filament Feed?

My solution works for me.

I use a single spool roller (that the spool sits on) using skateboard bearings on top of the Lack enclosure,

It feeds directly down through a double cone in the lid. Filament only touches at one point.

From there it goes directly down into the extruder. No noticeable friction I can see. Extruder seems happy with it.

RE: Tension-Free Filament Feed?

I'm using auto rewinding spool holders and long bowden tubes from a drybox under the table to the MMU. originally I had friction issues but i finally was successful by switching to 2.5mm ID tubing.

RE: Tension-Free Filament Feed?

Hi Bobstro, I also use the reverse bowden setup. I designed and printed myself a small part which is attached to the upper right end of the frame. (I used longer screws to mount the top end of the right z axis and conutered the part with nuts. This rather flexible part reaches out about 80mm from the side of the frame and holds a pneumatic coupling. My spools sit on a roller bearing holder to the right side of the printer. I use good bearings and haven't had any problems with friction even with 2.6kg spools.

The flexibility of the bowden holder also helps with leveling out tension on the filament a bit. You can see it moving up and down slightly when the printer retractrs.

I guess you could easiyl build yourself a similar system which extends to the back from the top of the frame to feed multiple spools into it, by switching the bowden tube at the extruder depending on the filament for example.

RE: Tension-Free Filament Feed?

Bobstro:

I cannot take full credit for this suggestion, it was first posted by TIM-M30 previously, but I will take credit for bringing it up here 😀 😀 😀 ...

I have a LACK enclosure with a slot type guide in the top for the filament, the slot is approx 150MM wide - I got it from Thingiverse, and use a PVC tube filament holder for the spools...  Tim-M30 suggested in a thread to move the filament holder from a front to back enclosure orientation to a side to side orientation.  e.g. the spool holder is on the side of the slot instead of in front or in back of the slot the filament goes through.

It works surprisingly well and has eliminated the slight binding issues and creaking when the extruder is at the right most or left most printing position.  If possible, if you could orient your spool holders to feed to the sides instead of front to back, that could be an option to try.  Especially if you have a slot type opening for the filament to feed through on the top of the enclosure.

I think the theory is that the extruder moves side to side in a fixed place but is stationary front to back so no binding.  It works for me...

Again, If I could find the post in that thread, I would upvote it, but it was a couple of weeks ago so it is lost in the ether, but it was helpful to me... original credit to TIM-M3o for the suggestion, but to me for keeping it alive 😝 

jbinfl 

RE: Tension-Free Filament Feed?

Posted by: @jbinfl

[...] I think the theory is that the extruder moves side to side in a fixed place but is stationary front to back so no binding.  It works for me...

That's a great idea. Unfortunately, the rack I'm using (19 inch audio rack) requires me to position the filament on the shelf below the printer, so I'm having to feed out the back, up to the printer on the shelf above and over the top of the printer. It works, but I'm sure the increased friction isn't helping my finish consistency.