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Posted · next UM nozzle ? Wish List
I'd really like to know that Ultimaker has the kidney stone problem sorted out. Developing a plug a few hours into a big print would be horrible.

So far all accounts on plugs that I know off on new machines have been wrong assembly. Where this part is assembled wrong:

http://www.flickr.com/photos/ultimaker/8185563116/

(top thing wrong way around, this is correct)

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    Posted · next UM nozzle ? Wish List
    I think you would need white for the fourth instead of black. The other 3 colours mixed will produce black.

    theoretically mixing the 3 main colours gives black but most of the cases its more of a grayisch brown...

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    Posted · next UM nozzle ? Wish List
    So far all accounts on plugs that I know off on new machines have been wrong assembly. Where this part is assembled wrong

    I was reading in your blog about the various clip issues (having to double up the plastic ones, would metal would be better) and I noted in the Make Magazine review that clips weren't actually included in the kit they reviewed. Has that upgrade been rolled into current production ?

     

    Onesuch fix is a printable shim to keep the

    Bowden tube from moving backward during

    retraction and causing ”stringing“ on

    prints; one should probably ship in the

    box, as we experienced this issue as well.

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    Posted · next UM nozzle ? Wish List

    The white clips have been replaced by better blue clips. We identified the varying quality of the white clips are the problem, combined with some bad bowden tubes. So the white clips where replaced by higher quality blue ones from a different supplier, and the bowden tubes undergo extra testing.

    Anyhow, the bowden moving up, caused plugs, in the V1 hotend. With the V2 hotend the teflon piece prevents this plug from forming. And with the V2 hotend the hot zone is shorter and thus there is less heat moving up, giving even less chance for the plug to form.

    My blog, with the dual clips, is still with the white clips, on V1 hotends. So it's outdated and I plan on updating soon.

    It's still serving me fine, but the V2 hotend works better in dual extrusion, and I have some bad bearings that I need to replace.

    With the new blue clips, we assembled 25 machine, not a single had a moving bowden tube. Now, the tubes are still a slippery thing, as they are slippery by design. But the new hotend, with the blue clips should prevent bowden popping.

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    Posted · next UM nozzle ? Wish List

    So next question... Where's the "thumbs up" emoticon ? ;)

    I love that you guys are just rolling in updates and improvements as you go.

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    Posted · next UM nozzle ? Wish List

    Bump:

    Hey guys,

    I'm new to the 3d printing scene, and am hoping my Ultimaker kit ships in about a week, so I can get started!

    I'm a mechanical engineer and avid designer, so not having the printer hasn't held me back much from thinking about ideas for upgrades (for better or worse, hahaha)

    Today, I spent some time looking at hot-end designs and thinking about possible improvements. Some of which may be off-base, since I don't have anything in my hands yet. It seems that key points would be to have a very well controlled and uniform temperature hot zone, which transitions as quickly as possible to the cold zone. The current hot end with a single power resistor, thermistor close by and no insulation, seems like it would lead to inconsistent filament heating when fan speed / ducting, print head speed, extrusion speed, or ambient air temp changes.

    What if the aluminum heater block was cylindrical instead, with a u-groove cut in a helix around the outer surface. Then a flexible heating cord like this: http://www.omega.com/ppt/pptsc.asp?ref=HTC&ttID=HTC&Nav= was wrapped in the groove. You could then wrap an insulative sleeve on top of that, and have a very evenly heated hot-end with less heat loss (radiant and forced convection from the cooling fan).

    For the transition to the cold zone: The heater block threads onto the nozzle (like normal), moving upwards you have a short thin walled section (of nozzle) to reduce conductive transfer, then back to OD threads to which you would attach a small heat sink similar to this: http://media.digikey.com/Photos/Tyco%20Photos/4-1542005-0.jpg . You could then redesign the fan duct to create a small airstream aimed at this cold zone heat sink. It makes sense to also use an insulative washer between the heater block and heat sink.

    I'm just throwing stuff out there... hopefully it turns into a great discussion with contributions from the very experienced on here, and eventually some upgraded parts!

    -Lars

     

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    Posted · next UM nozzle ? Wish List

    Why is this topic still pinned? Started over a year ago and its been 5 months since the last post. The fact that its at the top could only hurt the reputation of our favorite printer - although the hot end weakness may be largely overblown.

     

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    Posted · next UM nozzle ? Wish List

    Hmm, I'm not sure why it was pinned in the first place. I unpinned it.

     

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    Posted · next UM nozzle ? Wish List

    Here is my take on a new hot end.

    Stainless steel insulator with thin section, aluminum heat sink and cooling fan.

    The transition zone is about 4mm and the over all hot end is about 10mm longer than the stock one. I plan to make a shorter one and test it soon but this setup has successfully printed 5 medium to large PLA parts and 10 ABS parts without a hitch.

    Hot End 1

    Hot End 2

     

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    Posted · next UM nozzle ? Wish List

    Jep. I have a E3D-Hotend-heatsink with UM-Heatblock, Thermocouple and Heater so our hotends are basically the same.

    I have made only good experiences with this one.

    So for UM3: Switch to active cooling for hotends.

     

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    Posted · next UM nozzle ? Wish List

    The UM2 has active cooling: it has a third fan that cools the top of the filament tube.

     

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