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  1. #21
    Engineer clough42's Avatar
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    I have been thinking about retracting the hot ends for a while. The video below didn't work for me, so I'm not sure what it shows. [Edit: Ahh...beerdart, so this is the spring-loaded hollow-bolt hot ends?] There is at least one rocking extruder system on Thingiverse that uses a servo and a cam to rock the whole assembly left and right, pushing the unused tip onto a metal spring to stop the ooze. There are also various hot end setups that use the filament pressure to force the hot end downward against spring pressure.

    I have looked at the rocking option, but didn't immediately come up with anything I loved. The biggest challenge with is the pivot. Getting something rigid, precise and repeatable with off-the-shelf parts (3D printed and common bearings) is tough. Maybe I'll keep playing with it.

    Another idea that's floating around out there is independent hot end assemblies that can be picked up by the carriage with electromagnets and parked at the side of the printer when not in use. This would pretty much have to be a bowden setup.
    Last edited by clough42; 07-06-2016 at 04:06 PM. Reason: Added more detail

  2. #22
    Engineer-in-Training beerdart's Avatar
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    The hollow bolt was v1 the vid is v2. Its a E3D hotend with the top groove machined off and a new top hat attached with a hollow flat head screw. The mounting plate was thickened and a tight tolerance brass bushing pressed in and a wave spring is used for retract. Ill snap some pics next time one is off.

  3. #23
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    Quote Originally Posted by clough42 View Post
    Many of you are aware of my collection of single and double extruders and upgrade parts for MakerFarm printers. Everything I've done to date has been based on my needs and the things that bothered me. I'm thinking about what's next and thought I'd toss the question out there for the community.

    What do you like about your printer today? What frustrates you?

    What kinds of upgrades would you like to see? What would make the printer better?
    I would really like to see improvements for multiple filament printing. Maybe I just haven't spent enough time tuning my printer, but the inevitable ooze from the unused hot-end almost always ends up with a nib that breaks the print loose, or drips some unwanted color/material into the print. The temperature drop/retraction method for the inactive extruder works fairly well, and the pillars method wastes too much filament to be practical in my opinion. The retracting hot ends I have seen seem unduly complicated and I question repeatability with reasonable accuracy.

    I have seen a couple of clever servo mounted wipers for the nozzles on delta printers, but have not seen it implemented in a prusa frame as of yet. Would it be possible to mount something like that on the X carriage (so as to move with the Z axis)?

  4. #24
    Engineer clough42's Avatar
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    Quote Originally Posted by dustmann View Post
    I would really like to see improvements for multiple filament printing. Maybe I just haven't spent enough time tuning my printer, but the inevitable ooze from the unused hot-end almost always ends up with a nib that breaks the print loose, or drips some unwanted color/material into the print. The temperature drop/retraction method for the inactive extruder works fairly well, and the pillars method wastes too much filament to be practical in my opinion. The retracting hot ends I have seen seem unduly complicated and I question repeatability with reasonable accuracy.

    I have seen a couple of clever servo mounted wipers for the nozzles on delta printers, but have not seen it implemented in a prusa frame as of yet. Would it be possible to mount something like that on the X carriage (so as to move with the Z axis)?
    It's possible. Wiping will help, but not if the nozzle keeps oozing.
    Last edited by clough42; 07-18-2016 at 11:37 AM. Reason: spelling

  5. #25
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    Hi

    One "obvious" solution to the drip drip drip might be to drop the temperature on the hot end when it's not in use. Yes that has zip to do with extruder design ...

    Bob

  6. #26
    Engineer clough42's Avatar
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    Most slicers that support dual extrusion have this option. It definitely helps, at the expense of print speed.

  7. #27
    Engineer-in-Training beerdart's Avatar
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    Quote Originally Posted by beerdart View Post
    The hollow bolt was v1 the vid is v2. Its a E3D hotend with the top groove machined off and a new top hat attached with a hollow flat head screw. The mounting plate was thickened and a tight tolerance brass bushing pressed in and a wave spring is used for retract. Ill snap some pics next time one is off.
    Pics as I was cleaning up the hot ends.


  8. #28
    Have to get you and anvil and a forge. Hehe
    I know what you mean though. I would love to be able to print strong metal parts. It would solve some issues on the farm when something obscure breaks and you need a replacement in a short amount of time not a week or more.
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  9. #29
    That stuff looks great. Have to pay out an arm plus a leg for it but heck you could print a sweet looking replacement with this filament. Now I am wanting this. Just a few pounds of it. LOL

    Quote Originally Posted by curious aardvark View Post
    Now that IS a good idea.

    I've currently got one printer with a nozzle removed to avoid hassle.
    The other printer still has both nozzles attached. But it's a much better built machine and I've never had issues with the nozzle not in use. Plus I use it for dual material prints as well.

    Oh and roxy - there is a filament you can print and heat to get metal object :-)
    http://3dprintboard.com/showthread.p...rinting-Powder
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  10. #30
    Engineer clough42's Avatar
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    Thanks for posting the photos. That looks really good. How much vertical motion does it produce, and how does it register? Does the washer bottom consistently? Do you get any X/Y artifacts?

    I was thinking about something like this over the weekend, and this is very similar to what I was designing in my head, except my imaginary design had a much longer vertical stroke. Perhaps it isn't needed?

    What's with the nozzle? That doesn't look like an E3D part.

    James



    Quote Originally Posted by beerdart View Post
    Pics as I was cleaning up the hot ends.


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