Jump to content
Ultimaker Community of 3D Printing Experts

A different multi-extrusion approach - UM tool / printhead changer


Recommended Posts

Posted · A different multi-extrusion approach - UM tool / printhead changer

I'm currently thinking about the next iteration of this design and would like to discuss some points.

No bowden?

To my knowledge, a bowden setup might not be able to offer the level of extrusion control which is required for perfect multi extrusion. Any examples for really well working dual bowden systems?

If not, it's only direct drive (NEMA8) or flex.

Size matters

As this approach will typically use some printing area for parking unused print heads they should be as compact as possible. My first design features a footprint of 32 mm x 41 mm. The smallest print head I can imagine with a NEMA8 direct drive would be 22 mm x 30 mm. I think I've to go for the most compact design.

Of course things would be different if the whole printer was designed for a tool changer.

1.75 instead of 3 mm?

NEMA8 and flex both require a gear reduction in the the range of 1:40 to drive 3 mm filament. With a gear module of 0.5, the big 40 teeth gear wheel will be approx. 20 mm in diameter. This is kind of a hard limit for downsizing the print head. With 1.75 mm filament some 1:15 reduction should be sufficient, which corresponds to a 9 mm gear wheel. The 22 x 30 mm2 will only be doable with that.

Additionally, there would be almost no unwanted forces exerted by the filament to the magnetic mount or the parked print heads.

Your thoughts?

 

  • Link to post
    Share on other sites
    • Replies 1.3k
    • Created
    • Last Reply

    Top Posters In This Topic

    Top Posters In This Topic

    Posted Images

    Posted · A different multi-extrusion approach - UM tool / printhead changer

    @foehnstrum. Would you mind trying to run your Nema 8 motor at 0.6A and see how that works? The slightly higher torque variety that you are using isn't readily available in the states.

    I think the difference in current limit largley accounts for the difference in torque, so testing at 0.6 amps instead of 0.8A ought to give some indication of whether or not the lesser motor will do.

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    The first NEMA8 I tried was actually the standard type which is available everywhere. While it worked, it skipped steps at higher speed. In the "UM with direct extruder ..." topic I wrote about that in more detail.

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    Quick update,

    Finished the front left/right setup, did a few more prints including parking at every layer. Printing is fine but I need to dive into the retraction settings as the filament is pushed out the nozzle just a little to early causing severe strings, but hardly spend any time on this jet.

    Focused mainly on shaving of a few extra milimeters here and there of the head and docking unit. Printing ther final versions for now, both left and right. Did not get the UM ordered parts jet but still have hope it will arrive before the weekend...

    When the dual setup is ready I'll focus on getting things dialed in...

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    And about how to deal with the Gcode changes needed:

    Multiline Find And Replace

    For the testing, and adapting of Cura generated Gcode I liked to use a "multi line find and replace" plugin for Notepad++

    http://www.phdesign.com.au/programming/toolbucket-multi-line-search-plugin-for-notepad/

     

     

    And I'm looking at (not used yet) this option to do the tool change Gcode automatically in Simplify3D, here's a link;

    Simplify3D Forums - Scripts Tab: http://www.forum.simplify3d.com/viewtopic.php?f=8&t=1959&p=7574

    You will want to utilize the {IF OLDTOOL=XX} scripts.

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    ...

    No bowden?

    ...

     

    In the spirit of the Ultimaker concept: If it doesn't produce a good quality output - don't do it.

    Retraction in a Bowden-fed printer is useful to reduce oozing for the short time it takes the printhead to travel to a new position. After that, you have to continue printing or the nozzle will start to ooze.

    That is not useful for a dual-extrusion setup imho - because a toolhead might be parked for a long time until it's brought to use. A very good flow control is necessary in order to produce usable results.

    I'd even consider making a script that lowers nozzle temperature when toolheads are parked for long times.

    (Note: In conjunction with the "minimum layer time" feature, this script can be very simple and still produce usable results).

     

    ...

    Size matters

    ...

     

    True as long as you're constrained to an Ultimaker printer. I would choose whether to stay with the UM or make a completely different printer and then optimize the design only for that selected purpose.

    If someone else wants to adapt the idea for another printer, he'll have to adapt the design anyways. *Cough* I'm sooooo not designing a printer around the toolhead changing idea right now :cool:.

     

    ...

    1.75 instead of 3 mm?

    ...

     

    For me, 1.75mm filament is not an option. But then again, I won't be constrained by the Ultimaker's space budget. My current sketch says I have 248mm of space freely available for toolhead-parking. Thanks to the H-Bot configuration, I can use that whole space instead of just the corners. Also, I can increase any of the dimensions if necessary - it's still a sketch ;)

    If I read your post correctly, then this is mostly a "Should I develop my design further to fit into an Ultimaker printer, or go for a new printer entirely?" question.

    My thoughts on that:

    Making a proof-of-concept inside the Ultimaker is a very good and efficient way to develop this idea. It helps a lot if your design is completely reversible and easily mounted.

    Most people (probably everyone that already has an UM) will want an easy upgrade rather than a new printer.

    You'll lose valuable print space, but if it's reversible you can still cover most needs.

    In order to really profit from this design (have more than two toolheads at the same time), you'll have to use an H-Bot gantry, meaning a dedicated printer design. But how many people will really want need more than two hotends? Probably not that many...

    And to get the most out of it, you'll not only need a new printer (and electronics with enough motor drivers, cooling fan outputs and so on), but also further development in slicing software, such as the possibility to configure all these toolheads, have different tools use different layer heights and many other things that can be possible.

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    If I read your post correctly, then this is mostly a "Should I develop my design further to fit into an Ultimaker printer, or go for a new printer entirely?" question.

     

    You've read correctly between the lines :wink:

    The UM printers are one of the best to have and I like the attitude of the people there. However, their emphasis has been on reliability and quality the last two years not so much on cutting edge technology. I suppose (I hope) they will leave "Tim Cook mode" and enter Steve Jobs mode with the next things they come up with. But I've no idea where they're heading.

    If UM does it's homework with dual extrusion a tool changer conversion might become obsolete for UM3s because most people will be happy with a well working dual solution as you correctly said.

    As I've two businesses running I will not start a third one with a new printer. Maybe in two years with next generation electronics and firmware ;-)

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    BronzeFill @ 185°C and red PLA @ 205°C, 0.15 mm layer height

    The white one was just a test run. Will print some more, then they'll go into the vibratory polisher.

    gallery_5589_458_103322.jpg

    gallery_5589_458_126490.jpg

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    Almost done with the setup, as you see I'm still waiting for some components... feeders are mounted, see the end of the video.

     

    I'm happy with the latest itteration of the head, seems the weight balance is better, printing is fine except for the oozing, Want to test some different materials on there oozing properties but the weather was to good to be indoors today ;)

     

    Test print with about 80 tool changes.

     

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    Im glad to see you are getting the head to be more central. the more like the original you can get it the bigger the build volume will be.

    Would be nice if the park positions could recesses into the front frame a bit. but I guess there are limitations due to cables and bowden.

    Good work.

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    In dual extrusion setup the nozzles are rather far apart, so lots of build plate loss, but I consider this a purely experimental setup so I don't mind for now, I'm sure there's ways to go smaller if I would want to later.

    For the moment the loss of buildplate in single extruder use is not to bad, and should I need the full buildplate, which hardly ever happens, I can build it back to normal in a few minutes...

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    Just revisited KISSlicer and bought a Pro version, good to have more than one slicer to compare.

    As KISS offers custom gcode for "Select new extruder" and "Retire old extruder" it's easy to split the change movement pattern into the drop and pick part. A nice side effect: the toolhead status is always identical at the end of a print (both parked).

    One leave was actually sliced with KISSlicer.

    gallery_5589_458_86303.jpg

     

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    image.thumb.jpg.c0347a9102cd9195dfbb8d885352d1a6.jpg

    image.thumb.jpg.978f4d40a688c21385e109949602745c.jpg

    So far got everything working. Except that I need to print something for the second head. But both hotends are working and I just need to make the x/y gcode to do a final test with both extruders :D

    image.thumb.jpg.c0347a9102cd9195dfbb8d885352d1a6.jpg

    image.thumb.jpg.978f4d40a688c21385e109949602745c.jpg

    • Like 2
    Link to post
    Share on other sites
    Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer

    The system works, but I won't publish the stl yet. I think it can be improved to make more room and my design has 2 big flaws.

    1 - The fans on this orientation have very little room (23mm) or they hit the Z/motor/stuff.

    2 - The area used for the nozzle it's 20mm too big, I have designed a new aluminium holder that uses just 'enough'. It will take 2 weeks for the company that cuts the aluminium to sent it to me.

    3 - The way I aligned the main magnet changer forces to change the hole of the endstops (clearly foehnsturm saw this and his stl don't have that problem, but I changed stuff and well, I didn't saw it coming)

    Good stuff I found. There's no need for the 8mm aluminium, with 4mm and some nuts 'down' it works perfect to adjust both nozzles so both are on the perfect spot. (The photos show the alu with nuts inside, but I removed them on what I have.

    I'm going to align all the stuff from cero, and probably will place the heads on the end of the machine, to make the print area clearer.

    This is a early design, but there's much to change (alignment etc etc)

    5a330cedce73a_Capturadepantalla2015-04-21alas21_13_10.thumb.png.5152d35bd176733850f24a4e9918cc26.png

    5a330cedce73a_Capturadepantalla2015-04-21alas21_13_10.thumb.png.5152d35bd176733850f24a4e9918cc26.png

    Edited by Guest
  • Link to post
    Share on other sites
    Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer

    553a0f84b8493.jpg

    Still somewhat struggling with the new forum ...

    Edited by Guest
    • Like 4
    Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    Superb!

  • Link to post
    Share on other sites
    Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer

    Well the final-beta2 design seems rock solid. Now I need to wait for the new aluminium cut to arrive and I also made some 3mm MDF wood cuts for the area that holds the hot end isolator coupler (to use it in pairs and get 6mm).

    I still need to solve the fan design but now that both extruders are going to be on the end of the machine (I hope the bowden tension don't send them flying) anyhow the hangar and the hotend redesign seems to work just perfect.

    I'm going to use x3 10x4x2mm magnets N50 (1kilo each) so that should make a grip of 6kilos. If the magnets don't hold enough the hotend I can always design more room for magnets on the upper area without much problem.

    So until my new alu & wood arrive I won't be able to test much more. Here's some pictures of the size adjustment and how small footprint should have.

    Don't mind the print quality I'm using a very very cheap white pla kilo to run the tests.

    IMG_4711.thumb.JPG.1555c375f38deb9c7f3d4bd7421f4252.JPG

    IMG_4712.thumb.JPG.ec215a43103212aef75124a83952c68e.JPG

    IMG_4713.thumb.JPG.f4c5c2426db594ef5e82d2af57e4e8b1.JPG

    test.thumb.jpg.cb2568f216e79cf315d54a4949711f35.jpg

    IMG_4711.thumb.JPG.1555c375f38deb9c7f3d4bd7421f4252.JPG

    IMG_4712.thumb.JPG.ec215a43103212aef75124a83952c68e.JPG

    IMG_4713.thumb.JPG.f4c5c2426db594ef5e82d2af57e4e8b1.JPG

    test.thumb.jpg.cb2568f216e79cf315d54a4949711f35.jpg

    Edited by Guest
    • Like 1
    Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    Ahh, glad I'm not the only one waiting, still waiting for UM parts :(

  • Link to post
    Share on other sites
    Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer

    Finally I have almost everything, I'm waiting for my mini laser MDF parts but I think I'll just cut some wood by hand and replace it later.

    I changed the design for 20x4x2 magnets, but just because the magnet shop it's taking too long to order my N50 10x4x2 magnets.

    If my math it's correct (probably it isn't) the final print area will be 20x17 with 2cm2 (+/-) on the sides that can be used for nozzle cleaning. Also for my solution I'm using 1.75 filament (because I changed my UMO+ to work with it) so nozzle dripping should be minimum.

    Also I have a new hot end insulator tube in Titanium that I'll check with this. And I have another insulator tube made in titanium + tungsten coating that should (in theory and on paper) make printing with materials like wood (retractions specially) to work perfect.

    Here's the photo of this weekend that shows how small the head will be with the x2 4cm fans.

    5a330d25602bd_umomagnetic01.thumb.jpg.879bde65c74a1757f2147146ff2bb165.jpg

    I did this part so it's a one unit that fuses (by the long screws) to the head as a one piece block, easier to control and should make the unit well balanced.

    5a330d2586485_umomagnetic02.thumb.jpg.ee4fa7a41372e3445de2cb2099c4721f.jpg

    Redesigned aluminum holder. It has one advantage, you don't need to uninstall almost everything just to take the cable out. Probably on a later version I'll add something to clip the cables on the upper part near the bowden.

    The important area I think I did better it's that now the head and the fans are perfectly aligned, so the air always hits the same area from the sides, not like on umo+ default design that focus most of the air to where the head isn't, so it should make the cooling more even.

    5a330d25602bd_umomagnetic01.thumb.jpg.879bde65c74a1757f2147146ff2bb165.jpg

    5a330d2586485_umomagnetic02.thumb.jpg.ee4fa7a41372e3445de2cb2099c4721f.jpg

    Edited by Guest
    • Like 2
    Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    So, what is your experience with changing from 3mm to 1.75mm filament?

    I'm thinking about that too, because I could design my NEMA8 direct extruder considerably smaller then.

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer
    So, what is your experience with changing from 3mm to 1.75mm filament?

    I'm thinking about that too, because I could design my NEMA8 direct extruder considerably  smaller then.

    Why does the filament diameter have such a big impact on how big the extruder is? Is it just a matter of the required gear ratio?

  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    Well, 1:40 compared to 1:15 is less than half the size. With 1:15, a MK8 drive wheel and the gear wheel are more or less the same diameter. This allows for a different assembly. 55412f73b9f8a.jpg

    .. not sure if you can see much without a damned zoom function.

    • Like 1
    Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer
    So, what is your experience with changing from 3mm to 1.75mm filament?

    I'm thinking about that too, because I could design my NEMA8 direct extruder considerably  smaller then.

    Well the dripping it's almost non existant. Specially with E3D nozzles. I also have like 16 (not kidding) china ultimaker replicas modified for 1.75 that work well but because the hot area it's bigger they drip a bit more.

    My road to 1.75 wasn't easy and some say that 'just changing' the bowden it works but to have perfect workflow and zero jams (specially with weird materials) I had to change the heat break and the nozzles. The feeder it's not a problem since the default umo+ works perfectly if you file the plastic just 1mm so the minibearing/black plastic can push just as good as with 3mm. Also I can print a bit lower on C since there's less plastic.

    I still never did the speed test since I just print fine.

    Thinks that I tryed and failed:

    - Using robert feeder without changing the stepper it's just a bad idea since understrusion pops at 5mm2. I did that 2 weeks until gived up and whent back to the default feeder.

    - Just using a ptfe 6mm/2mm (they exist in the market for buddas) works but you need to change the bowden clamps and the white ptfe (not your case but for default umo+ this applys).

    - Without changing the nozle/heat break tube it works but there's a lot of dripping. One good werid think it's that I could atomic it easyly with one ptfe 3mm/2mm pushing a few times and I was able to leave the nozzle totally clean without wasting filament (I should tell this somewhere it might help others..) Atomic ptfee :D!

    So yeah. It works buying extra stuff (nozzle/barrel). You can retract faster and less mm or more for super clean retracts but I never did the speed test :D. In theory I should be able to push more filament since it's smaller...

    And that's my trip to the 1.75mm. I did it maintly cos I had a lot of euros in good quality filament (colorfabb, etcetc).

  • Link to post
    Share on other sites
    Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer
    Well, 1:40 compared to 1:15 is less than half the size. With 1:15, a MK8 drive wheel and the gear wheel are more or less the same diameter. This allows for a different assembly. 55412f73b9f8a.jpg

    .. not sure if you can see much without a damned zoom function.

    I am guessing that the blue box is the stepper motor. Not sure what the orange is and while I see the pulley I don't see the mechanism to hold it in place. Looks like the difference wouldn't be noticed in the original (non magnetic) modular head design, due to the difference width of the linear bearings. Still, looks interesting. At some point I will probably want to switch, and I already have almost enough parts to make 2 (would just need to order more bearings).

    On the topic of size, It looks like you used 10 mm OD bearing for the drive axle. Was there a reason you didn't use much smaller ones? Seems like 6mm OD is fairly common for a 3mm ID bearing.

    Edit: It actually looks like 9mm OD is what your design used. Couldn't find that locally, so I went with 10 mm and made the holes slightly bigger.

    Edited by Guest
  • Link to post
    Share on other sites
    Posted · A different multi-extrusion approach - UM tool / printhead changer

    That's just a draft sketch to check how parts could be arranged. The main difference is that the stepper shaft and the filament path could arranged on the same side of the main shaft with the gear and drive wheel. The orange thing shouldn't be orange ;-) it's the counterpart to the idler arm which is missing.

    To be honest, I just used the bearings lying in the box here. With 3mm ID and 10mm OD you can use the same bearing for the pressure wheel.

  • Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now

    ×
    ×
    • Create New...