Ultimaker 2 All Metal Hotend

Discussions concerning the Ultimaker 2 / Ultimaker 2+ series of printers, including the Ultimaker 2 Go
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Roboduck
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Ultimaker 2 All Metal Hotend

Post by Roboduck » March 24th, 2016, 11:20 am

I am on a quest to design a better all metal hot end for the Ultimaker 2. I hate replacing the PTFE thermal barriers and my experience with all metal hot ends in the past has been a bit disappointing (PLA is usually very hard to print with an all metal hot end). I have been toying with various designs for a while now but I think I am at a point where I am ready to make a prototype. The new hot end would mount directly to the old X-Y carriage without any modification. The heat sink portion is aluminum, the thermal tube is grade 5 titanium and the heater block is brass. My hope is that the titanium will help quickly dissipate the heat and prevent the filament jamming that is so common in all metal hot ends.

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Thoughts? Feedback?
Last edited by Roboduck on March 24th, 2016, 12:29 pm, edited 1 time in total.

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Re: Ultimaker 2 All Metal Hotend

Post by LePaul » March 24th, 2016, 11:27 am

I'm looking forward to feedback from are more techy members!

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Re: Ultimaker 2 All Metal Hotend

Post by Blizz » March 24th, 2016, 12:20 pm

I can't see any of the media? Just see forbidden signs

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Re: Ultimaker 2 All Metal Hotend

Post by Roboduck » March 24th, 2016, 12:30 pm

My bad. Should be fixed now.

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Re: Ultimaker 2 All Metal Hotend

Post by Neotko » March 24th, 2016, 12:31 pm

I can't see the img too. But I did extrusion test on umo+ changing the barrel to titanium with tugsten disulfide ws2 something like that to have a slippery inside. It didn't work.


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Re: Ultimaker 2 All Metal Hotend

Post by Neotko » March 24th, 2016, 12:33 pm

I used this company for the bath http://www.ws2.co.uk/ 72€ aprox to bath 8 barrels.

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Re: Ultimaker 2 All Metal Hotend

Post by Roboduck » March 24th, 2016, 12:53 pm

Do the images show up now?

I was going to make a bunch and try a few different things. I plan on getting at least one type II anodized which should give it a slightly slipperier and harder surface. The other thing will be getting a really nice surface finish inside the bore so I may send them out for electropolishing as well.

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Re: Ultimaker 2 All Metal Hotend

Post by Anders Olsson » March 24th, 2016, 2:10 pm

I have similar experiences with E3D all metal hotends and PLA.
The tests I did with metal couplers replacing the PTFE in the UM2 also showed problematic with PLA.

My theory regarding the E3D is that it might work with an all metal hotend and PLA if you use 1.75 mm filament and a powerful direct feeder, but with 3mm filament and bowden at least I am unable to get work reliably when printing things with lots of retractions.

First of all, I would like to remind you about the V3 TFM-PTFE-coupler/solid spacer combination that is delivered with the UM2+ machines: viewtopic.php?f=9&t=46
According to people it more or less solves the problem permanently, korneel says he has logged 7500 hours on one of those couplers: viewtopic.php?f=9&t=46&start=15#p1277

That said, of course it is interesting to develop new things :-)
Considering the thermal similarities if one compares your design to the E3D hotend, I am not sure you will solve the PLA issues with your current design.
It is a rather complex problem, trying to cool the filament in short enough distance for it not to stick or not cooling it that quickly and relying on a non-sticky surface.

Personally, I am still curious what happened to the Duratron PBI spacer that "glloq" made: https://ultimaker.com/en/community/8024 ... ge=6&sort=
It looked really promising, but glloq has disappeared and I have been unable to contact him again.

Duratron/Cerazole CU60 PBI appears to be the perfect material for the spacer when looking at the data: http://www.quadrantplastics.com/en/prod ... R-pbi.html
If I had more time I would have tested it long time ago.

Considering your design, again, the questions is basically in what way it differs from the E3D hotend that makes it likely to work better.
And if there answer is that it is not that different, how one can improve it.

I am really not a fan of the E3D hotends in general I have to say, so I am much looking forward to someone inventing something better :-)

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Re: Ultimaker 2 All Metal Hotend

Post by Roboduck » March 24th, 2016, 2:27 pm

I've seen those solutions before but I'm still not thrilled about any of them. From what I've experienced the problem with PLA come from heat creeping up the thermal tube and softening the PLA during retracts which cause it to expand and jam. My hope is that the titanium will help limit the heat creep. I also want to get rid of all the stacked components in the hot end so there is less risk of leaking or separation (i've been fighting some leaking now with the geared extruders). I would also like to use higher temp plastics and I have reservations about cranking up a hot end with PTFE in it. I am having a titanium heat break made just to try out before going ahead with a fully custom design.

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Image

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Re: Ultimaker 2 All Metal Hotend

Post by ivan.akapulko » March 25th, 2016, 4:22 am

For a better release of heat you may want to remove the extra rib in the Central part, leave only the mounting of the fan.

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Re: Ultimaker 2 All Metal Hotend

Post by Roboduck » March 25th, 2016, 8:21 am

Good idea. I've seen some people make an air duct to channel air over the heat break. Maybe I'll do that instead so I don't have to machine the aluminum.

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Re: Ultimaker 2 All Metal Hotend

Post by Anders Olsson » March 25th, 2016, 9:53 am

Regarding leaking, in particular with geared feeders, you need to replace the spring with a solid spacer to completely fix that problem.
The force of the spring is much to low to keep the coupler, regardless of what material it is made from, tight against the heater block under all conditions.

In the original UM2 setup it still normally works with the spring just because the extrusion pressure is mostly much lower than the maximum feeder pressure. The relatively soft PTFE also helps, since a tight seal against the heater block means there is no gap for the plastic get in between the PTFE and the heaterblock, eliminating the hydraulic force conditions that lifts the coupler.

Regarding the design in your last pictures, you will need either a thin plastic washer (like the I2K) in between the titanium and the heater block, or make a thin-walled section on the titanium coupler close to the heater block.
Otherwise you will conduct too much heat up into the titanium coupler, effectively bringing the whole piece above 60 C and melting the PLA all the way up to the bowden (from my experience, testing similar concepts)
Last edited by Anders Olsson on March 26th, 2016, 4:27 pm, edited 1 time in total.

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Re: Ultimaker 2 All Metal Hotend

Post by LePaul » March 25th, 2016, 10:42 am

What about a sealed liquid cooler (such as what PC's use for CPU and Graphics cards?) in the print head?

They already use a remote reservoir, are sealed (no adding coolant needed). The trick is the shape to heat sink for liquid to draw heat from

Again, I'm not an engineer. Just thinking out loud since I have seen liquid cooling go from fantasy to very reliable/compact in game machines.

Edit: For example, items like this Corsair Hydro Cooler

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Re: Ultimaker 2 All Metal Hotend

Post by Meduza » March 25th, 2016, 2:46 pm

It all comes down to getting it down in a small/light enough package to be able to mount it to the head without increasing the weight significantly.

We (me and @johan) did experiment with a setup to watercool the UM2 head a few years ago, i'll post some images in a separate thread :-)
viewtopic.php?f=9&t=197

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Re: Ultimaker 2 All Metal Hotend

Post by LePaul » March 26th, 2016, 2:52 pm

Good read....I'm also curious how a cooling solution would deal with a Bowden tube of its own :)

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