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Flexible shaft - the best of both worlds?


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Posted · Flexible shaft - the best of both worlds?

The flexible filament just arrived.

This is a test print with Formfutura's FlexiFil (a thermoplastic Co-Polyester with a shore hardness 45D).

It feeds and prints without any issues, however I had bad inter-layer bonding so far. Therefore I increased layer height to 0.15 mm and wall thickness to 1.6 mm.

 

 

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    Posted · Flexible shaft - the best of both worlds?

    Hi,

    I must say that I am really impressed by your design. Very cool that you've built this!

    I see that you use a hobbed extruder drive wheel and was wondering whether you've had any issues with the wheel clogging. I've done some tests with different types of grip patterns on the feeder wheel and the hobbed wheel performed best. However it also had the problem that it was prone to clogging. I was wondering whether you had any issues with clogging.

    Cheers,

    -Bas

     

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    Posted · Flexible shaft - the best of both worlds?

    Hi Bas,

    Thanks for the compliments.

    My experience with the hobbed wheel is limited so far. But yes, I'd say it is slightly more prone to clogging. I had no issues until now but I already noticed one or two grooves filled with some PLA residues.

    I still a little uncertain about the correct contact pressure. The grip is very good although the marks in the filament are less visible than those produced by the UM bolt.

     

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    Posted · Flexible shaft - the best of both worlds?

    That's really good quality for flex! What were your print settings?

     

    Well, better, way better now

     

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    Posted · Flexible shaft - the best of both worlds?

    Looks like an awesome system !

    I have a question though. What made you go with the 1:20 worm wheel gears ? And not for example a 1:1 conical gearset ?

     

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    Posted · Flexible shaft - the best of both worlds?

    That part is not my idea. It's http://mutley3d.com/ work. Without the high gear ratio the flexible shaft would not handle the necessary torque.

     

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    Posted · Flexible shaft - the best of both worlds?

    @jhertzberg

    If I remember correctly settings were almost normal: 0.1 mm layer height, 1.2 wall thickness, 30 mm/s printing speed, retraction speed 30 mm/s, temp 215°C (for FlexiFil)

     

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    Posted · Flexible shaft - the best of both worlds?

    Hi!

    I've also noticed that the hobbed wheel seems to cut more into the filament while the knurled wheel seems to push and deform more. The only disadvantage that I found was that when the wheel really slips over the filament (e.g. in case of a clogged nozzle) then the grip pattern really clogs which dramatically decreases grip. However the grip was superior to the grip that I could reach with a knurled feeder wheel.

    I have the suspicion that the hobbed wheel is also a bit more efficient in transferring power to the filament because the grip pattern cuts better into the filament, resulting in lower losses. A while ago I've done some measurements on the grip versus the idler wheel pressure for different grip patterns, If you'd like I could send you the results.

    I've also done some measurements on the feeder loss versus the idler wheel pressure (the higher the pressure, the higher the grip, but also the higher the losses induced by deformation of the filament). I'll try to repeat this measurement this afternoon but then with a hobbed wheel. That way I can seen if the hobbed wheel is more efficient.

    Cheers!

    Bas

     

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    Posted · Flexible shaft - the best of both worlds?

    I did a quick comparison between the hobbed and the knurled feeder wheel. I fed a piece of PLA through a feeder while measuring the torque on the feeder motor axis with a torque sensor (no bowden tube and no hotend present). I used a hobbed wheel and a knurled wheel of the same diameter (8mm, for the hobbed wheel the diameter at the lowest part of the curved surface).

    At the same idler setting, a higher torque was needed to feed the material through with the hobbed wheel. However the hobbed wheel also had a higher grip than the knurled wheel at the same idler setting. So in the end it doesn't seem to make too much difference.

    -Bas

     

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    Posted · Flexible shaft - the best of both worlds?

    Ordered one today for use on my UM2. It has to be an improvement over trying to push spaghetti thru a tube...

     

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    Posted · Flexible shaft - the best of both worlds?

    EldRick please post about it when you have assembled it.

     

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    Posted · Flexible shaft - the best of both worlds?

    Ordered one today for use on my UM2. It has to be an improvement over trying to push spaghetti thru a tube...

     

    I see. You will remote-pull the spaghetti... ;)

    I'm also looking forward to get more news on this.

     

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    Posted · Flexible shaft - the best of both worlds?

    I'm really really starting to get an itch to try this. But I don't know if I can... kinda need my machine to be somewhat stock for work... Maybe I could get another head assembly so I can "quick swap", hmm.

     

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    Posted · Flexible shaft - the best of both worlds?

    Nooo - don't do it! You _need_ to improve your awesome feeder :p

     

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    Posted · Flexible shaft - the best of both worlds?

    Hah :p I accept bribes, PM for Paypal address :p

    But if this could be made to work "perfectly" I think it's the way to go, it would remove a lot of head aches.

     

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    Posted · Flexible shaft - the best of both worlds?

    Lets wait for the announcement tomorrow. Maybe they'll just present the UM3 with flexible shaft... :D

    About bribing... come on, what else would you need other than a (non gay) man hug?

     

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    Posted · Flexible shaft - the best of both worlds?

    UM3 would be wrong... unless its actually a UM mini or bigger and no one noticed it in the videos

     

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    Posted · Flexible shaft - the best of both worlds?

    UM3 would be wrong... unless its actually a UM mini or bigger and no one noticed it in the videos

     

    Hmmm... interesting thoughts... :ph34r:

     

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    Posted · Flexible shaft - the best of both worlds?

    Will it be that UM-mini that Daid was working on 2 Ulti-eve's ago? :p

     

    I mean...Just saying :)

     

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    Posted · Flexible shaft - the best of both worlds?

    So you expect a SMALLER printer to be announced in AMERICA?

     

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    Posted · Flexible shaft - the best of both worlds?

    Actually I don't, but since pm_dude was saying that nobody noticed, I just wanted to say: i did! :)

     

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    Posted · Flexible shaft - the best of both worlds?

    @Bas: I remember reading your report, but I cannot seem to find it anymore. Would you mind posting it again?

    Also, what hobbed wheel have you used?

    The knurled wheel on my Ultimaker 2 has a tendency to slip off the drive shaft after few hours of printing. It's getting really annoying so I'd like to try some alternative.

    Thanks!

     

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