Um2 hotend design questions

Discussions concerning the Ultimaker 2 / Ultimaker 2+ series of printers, including the Ultimaker 2 Go
Anders Olsson
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Re: Um2 hotend design questions

Post by Anders Olsson »

Neotko wrote:They printed flawlessly with my perfectrobot settings simulating a 0.28nozzle with my umo+
You might have to scale the outer ring until it is a tight fit though, as I wrote in the PM.
It is a fine pitch tread, so just slightly too much play and it might collapse under load, it is good if you test this before installing it in the printer.

Here are the files if anyone else is tempted to play with this thing: https://dl.dropboxusercontent.com/u/102 ... cement.zip
:-)
The I2K-version is thinner, only use that one if you actually have an I2K-washer installed.

Please note that this is a prototype!
I might spend some more time on this and upload the files somewhere else in the future if I think the designs works good enough.
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Neotko
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Re: Um2 hotend design questions

Post by Neotko »

Wow so far it's printing pretty great. Thanks Anders!!

Btw I didn't scale it. It screws in and out without force or play, it's really grrreeeat.

I have a i2k but forgot to install it XD so I'll try to break the spacer first with a two days print.

Maybe because I used a 0.28nozzle it fits so well (using a 0.40). My perfectrobot settings are really nice for 0.06-0.1 layers with overhangs.
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Neotko
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Re: Um2 hotend design questions

Post by Neotko »

Wow it's printing quite great.

Image

And it's amazing. First time I see a second top layer almost perfect. Ruby + um2 hotend :O

Image

Btw that print has 5k retracts in 21minutes.
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Meduza
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Re: Um2 hotend design questions

Post by Meduza »

That top surface is beautiful!
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Neotko
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Re: Um2 hotend design questions

Post by Neotko »

And it's printed at 60mm/s 0.2 layer 210C with fans just at 40% giving very little air. It nice to see that I can keep printing at the same speeds/settings than my other umo+, I don't even need to touch my job files gcodes.

What still bothers me (not really but it's strange) it's that the um2 fans don't start until 102/255 (just like my 40x40x20 fans) and ofc they need the Kickstart from the Amedee experimental firmware.

I need to run some acceleration tests since the hotend weight it's less I should be able to use more than 3000 for x/y. Anyhow it's printing very very nice. I might need to start save some cash to upgrade my other printers in the future.
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Meduza
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Re: Um2 hotend design questions

Post by Meduza »

Another benefit of the UM2 head is that you are able to replace the sides of the UMO with solid ones (or even frosted plexiglass ones like UM2) if you want and have access to a laser cutter, to make it a bit more enclosed :-)
Anders Olsson
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Re: Um2 hotend design questions

Post by Anders Olsson »

Meduza wrote:That top surface is beautiful!
I agree, that is certainly one impressive top layer! :-)
You must have tuned the flow rate very carefully, Neotko?
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Neotko
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Re: Um2 hotend design questions

Post by Neotko »

I didn't touch a think, just changed my dead magnetic head changer to um2. Inserted your space adjuster, changed PID and printed that as first test.

This for me confirms that my esteps for 210/0.2 layers are spot on.

Also this coral smartmaterials pla it's really nice (not all colors print well but they sell it as 0.03 error, and imo better than colorfabb, and close to Faber dimension stability.
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Neotko
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Re: Um2 hotend design questions

Post by Neotko »

Another think I changed on my umo+2 I ditched the um2 motor. Compared to my others umo+ that use umo feeder (same motor used on x/y) I saw a quite large error rate on tract/retraction. My keychains use around 5k retracts in 25mins so when I printed 3-5 at the same time many errors did show on prints. But when I changed it to umo feeder (gear-less) everything went back to normal.

Purocomo made a comment about this and linked a stepper test that's very interesting:

My post
https://ultimaker.com/en/community/1703 ... ply-141192

His answer below

And his post on stepper forum:
http://tinyurl.com/gm5eju3
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Neotko
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Re: Um2 hotend design questions

Post by Neotko »

It's weird this um2 hotend. It handles better the constant extrusion on small areas with zipzag but also it generates a little bit more (and visible) pressure when extrude-retracts. I'm getting with ruby and e3d more little small blobs even after the wipe/extrude. Also a really weird effect, and must be related to the pt100 china I'm used (because my pt100 died along with the aluminium umo block). I'm getting with faberdashery, on my umo+2 machine Matte prints, and they start to recover a bit of shiny if I go from 210 to 215, but I don't like 215 since it make's the small blobs from layer change/wipe/retract a bit more visible. But also, at 210 the prints are totally MATT colored but on my other 2 umo+ they are glossy... It's a really really weird side effect. I think umo+2 hotend need's a higher amount of wipe/coasting than umo+ hotend, probably because umo+ has a bigger hotzone (probably two times bigger at least) and the filament when it goes from cold-hot-cold it has a longer 'hot' state allowing the extrusion to be hotter, but also since the filament goes like that, it colds faster?...

I need to make a 40x40x20 fan cap for this umo+2 hotend so I can get real airflow moving, um2 fans are really really bad. Hopefully um2+ push more air.
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Re: Um2 hotend design questions

Post by Neotko »

Well seems the weirdness from the matte color comes from faberdashery. I'll contact them about this because the new pink spool and the 100m mint filament do the same exact think on 3 machines. They are matte at 210 at 215 they get some glass back and at 220 they are gloss. This for me means that my china umo couplers will last less time and I get a little tinny bit of unwanted drips.

Btw the umo+2 it's printing just as good as my others umo+. This hotend it's quite great with the olsson. And btw @anders! i just noticed that with your compresion spring replacement you don't even need to disassemble the hotend to change the coupler... Amazing! So far it's been printing 20-24h total and it's just fantastic (and it's pla printed).

Edit: No sorry I just tryed and no, but almost! Maybe with a few adjustments it could be done I think. But ofc I suppose that when you have the steel coupler perfectly set its better not to touch it? Umm...
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Re: Um2 hotend design questions

Post by Neotko »

One good think about the adjust-able spring replacement it's that if you need to screw the upper parts the distance changes sligly so you can readjust the distance to avoid over preassure. So far I been printing non stop and the pla holds up with no deformation (been printing at 210-215)

Btw 1.75mm on um2 hotend can use even less retracttion distance.

First test point at 2-2.5mm. 3.2mm retracts caused back preassure blobs. Ruby nozzle it's quite amazing to diagnose the hotend problems.

This test was done with e3d nozzle:
https://ultimaker.com/en/community/2040 ... alibration
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Neotko
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Re: Um2 hotend design questions

Post by Neotko »

Yerterday saw a big mama leak under the ptfe steel coupler. Olsson adjuster broke, well a bigmama mess. The mistake was not cleanning good enough the steel coupler after the first leak (the one with the bad spring).

Today seems it's all ok. But the most interesting part.

UMO+2 world first fan cap (only for umo/umo+) for um2 hotend.

Image

Image

Based on my soon to be released Symmetric fan cap.

Why it's so good but um2 users can't have it:

- Symmetrical fan air. Centered, equal air distribution from nozzle center.
- Really powerfull empapst 40x40x20 414H 24v fans (and they only use 68mA each).

This DOES cold down.

And so far it's printing beautifully!

I'll post the design in a few days. It's really sweet.
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Re: Um2 hotend design questions

Post by Neotko »

Oh and the weight of the hotend it's almost the same because carbonfill weight it's less than steel cap.
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Re: Um2 hotend design questions

Post by Neotko »

Well I'm starting to hate quite a bit the um2 hotend.

- I get silky looking prints on umo, but for the love of god I can't get the same quality on um2hotend. But, the layer to layer quality it's better... It's very puzzling.
- I need to go to 225C to start to get a glossy look on faberdashery, when on umo I can hardly even get a matte look. It's ok, for some materials, but it's a pain in the ass to keep the same print quality among the printers.

And most important, and I need a bit of help with this because I still keep getting microleaks between the heat block and the i2k, and it's quite a mess. The coupler it's on perfect shape, no curves, spins beautifully on a filament peace and it's white as milk. But I still wonder, on all the instructions and photos I see the Steel coupler must be all in, but with a twist out so isn't touching the block (makes sense since that would change the heat on the block) but please tell me a think. It doesn't really matter right? The important it's that the ptfe/i2k/block are connected with enough pressure so they don't move when the filament pass trough. Pretty much like any pipe system. So my question it's.. Doesn't the heat creates gaps when the metal/plastic expands because the heat? And if so, I should tight all while it's hot isnt? Because if not I don't get it. On umo this it's just so easy.

I'll try to use a china umo nozzle to see if I can increase the hot area to gain the gloss back, because without that this hotend it's pretty much useless, and I don't trust pla print at 230C+ just to get the gloss when I can get the same perfect smooth prints at 210 on umo+.

Anyhow I still need to test with other pt100, but I wonder if there's any source of trusted sensors that aren't the 48€ ultimaker charges for the new pt100's of the um2+.
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