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Parts to print flexible filaments

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Hi All,

I am currently trying to design a printhead dedicated for flexible filaments as part of my bachelor thesis project. I am wondering wich feeder and which hot-end is the best for flexible materials. I'm talking about <90 Shore A stuff like ninjaflex, filaflex etc.

I'm currently thinking the bondtech QR and E3D V6 might do the trick. Is there anybody who's tried printing flexible filaments with those parts?

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Well putting the feeder on the head helps a lot with flexible filaments. The friction between the bowden and a rubbery filament is high. Adding oil to the filament helps immensely.

But if you want to keep the feeder on the printer then the iRoberti feeder is great. You need to include the part that doesn't let the filament bend. That part could use some improvement! That might be a good project.

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Well putting the feeder on the head helps a lot with flexible filaments.  The friction between the bowden and a rubbery filament is high.  Adding oil to the filament helps immensely.

But if you want to keep the feeder on the printer then the iRoberti feeder is great.  You need to include the part that doesn't let the filament bend.  That part could use some improvement!  That might be a good project.

 

I Like iRoberti's designs, but I think placing the feeder directly above the hotend is the best/only way to get repeatable quality in printing flexible parts. Also, as I am conducting my thesis project in a company environment, It would be a plus to be albe to make use of of the shelf parts (like the E3D hot-end and the bondtech feeder). The design process I am going through is mainly selecting the right components, and finding a way to make them work together. That's why I want to know if people have already used those parts (seperately or together) to print stuff like ninjaflex.

To give an idea on the direction I am going; I am planning to design a bowden-direct hybrid dual extrusion printhead with one nozzle retractable. I'm hoping to be able to post some screenshots soon.

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I have not run the Bondtech feeder before so I can't chime in on how it does with flexible, but I have run kilos through the E3D-V6, the Printrbot Ubis Ceramic and Ubis 13S hot ends, as well as through my UM2 with an Olsson Block. I've also messed with flexibles through a few different TAZ5/6 machines with their hexagon hot end, I liked them but don't own them so I can't go into too much depth about their reliability over many prints.

I gotta say the E3D-V6 does remarkably well with it. While I don't necessarily have experience with with the Bondtech, I do have a lot of time "playing" (read messing-up) with prints from different direct-drive extruder setups.

What I have found is that a lot of direct drive machines do well with flexibles, but the filament has to be supported directly after the drive wheel. The Printrbot Aluminum Extruder (V2) is a good example of this compared to their older aluminum extruder. Their older extruders did mediocre with inserts which could be printed, or any tube you found that could be cut to length and fit as a filament guide. The V2 has the extruder machined much closer to the gear to eliminate the gap between the feeder wheel and the guide. What I see flexibles do is mushroom between these two joints and jamb.

The TAZ extruder handles flexibles very well, as well...but it sounds like you're looking for a off-the-shelf, non-printed solution. If printed parts are okay, LulzBot offers a TAZ flexystuder toolhead with their all-metal hex hotend on their site, which I would imagine does a pretty good job. From what I have seen of the TAZ extruders modified to print flexibles, I wouldn't hesitate to hack that to a machine and go to town.

One thing I typically recommend when picking an extruder or extruder design and are planning on printing flexibles is to make sure whatever you use is easy to take apart and get to the filament path in case you do have mushrooming.

I looked at the Bondtech site, but didn't see much at a quick glance about the inner-workings...at least not as far as cross-sections of the filament path go.

I do have a buddy who prints a lot of flexible filaments on his bowden self-source machine. He swears the best way to do it is to mount the feeder directly over the printer and the spool about 12" directly over that. He ends up feeding almost straight down the tube and into the hot end, removing the bends/friction. I've been meaning to try it, but have a pile of repairs/upgrades already waiting for my machines, I was thinking of building an extruder to mount and adding a pigtail with a connector where I could swap between it and the on-board extruder for my UM, it has a permanent home now where I could do something like that, swap the connector/bowden and swap setups in a couple minutes....gotta try it first and see if it as awesome as he says. I finally started feeding from the floor and am gonna enjoy that setup a few more weeks before I play with it again.

Sorry for the long, rambling reply...I did a lot of playing with flexibles a year or so ago so had a lot to spit out!

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[...]

Sorry for the long, rambling reply...I did a lot of playing with flexibles a year or so ago so had a lot to spit out!

 

Hi Yoter,

thanks for your reply. I have looked into te TAZ printhead, and it seems quite bulky and heavy. Not that my own design is going to be a small featherlight thing but still... Also i saw on the lulzbot website that it's not advisable to print rigid filaments with the extruder that is design for the flexible stuff. I would like to keep the option of printing rigid filaments too.

I have begun designing a printhead with the bondtech extruder and two hotends. This is going to weigh around 500 grams, so I'll have to calculate how much the guiding rods will bend under this weight. I'd like to keep the maximum vertical displacement as a result of bending under 20 micrometer. The original setup, with the 6 and 8 mm rods bends around 17 micrometer with the original printhead, so it looks like i'm also going to have to place some thicker rods. rods bends around 17 micrometer with the original printhead, so it looks like i'm also going to have to place some thicker rods.

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