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Watercooling the Printhead


Simon2.4
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Ok my next mod is a biggie: After some experience printing with my heated chamber, I've hit the limits of what I can do with a normal extruder. I tried 65c and ran into issues with cooling the top end with the hot air so 60c is the limit for now.

I designed a water jacket to fit right on the unmodified E3Dv6 heat sink:

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Directing flow with these ports:

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It's designed to fit with the Halo duct on the Afterburner carriage and the original back plate for the E3Dv6:

https://github.com/tsitalon1/VoronUsers/tree/master/HaloDuct

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For the loop:

silicone tubing in 3 sizes:

-6id 8od to run along the cable chains on the x and y axis

-8id 12od to run along the Z axis cable chain

-12id 16od for everything below the z chain: run out of base, radiator, pump.

Pump: Chinese 24v 22w pump with 1/2 npt threads: https://www.amazon.com/Water-Circulation-Brushless-Noise-Electric/dp/B09YHTN6W7/

radiator: Chinese 360mm rad; big for passive cooling

Watertight??

hopefully...

This is not a job for fdm printing I'm going to get it printed by JLCPCB using stainless steel SLM and since it's so cheap, I'll also order nylon MJF which should also work fine and much lighter.

To assemble the parts, the idea is to inject silicone in the hole to fill the whole space between the first and last two fins to bond and seal. Done with a syringe with a blunt needle.

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I'd love to hear your thoughts on this I haven't ordered anything yet I want to think this through and get other's opinions first.

 

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Wild and cool idea - love to see how this goes.

Like the bracing on the tube nipples - nice.

It's gonna be all about the sealing.

What do you plan to run for the coolant?  Diluted anti-freeze?  Though the heat sink is anodized, a little corrosion protection would be good insurance.  If you can keep the pressure down, that should help sealing as well - you might be able to run the 24v pump at a lower voltage to reduce the pressure and reduce the strain on the silicone.  You need flow but you don't need super huge volume so a modest pressure will be all that's needed.  With the water cooling, the aluminum expansion from temp rise will be minimized which will help keep the sealing in place as well.

Edited by zogzogzog
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9 hours ago, zogzogzog said:

What do you plan to run for the coolant?

I have an unused bottle of pre-mixed EKWB fluid for PC cooling so I'll probably use that.

9 hours ago, zogzogzog said:

keep the pressure down

I need about 1.5 psi to maintain a flow of a foot a second through 1/4 inch tubing.

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Plugging the water pump directly to the 24v fan headers:

According to this, I could just plug the pump instead of a fan on the BTT octopus; max 3amp on the connectors is the limiting factor. The pump's description says 'brushless' which implies a controller circuit onboard, so no (or little) concern with startup current inrush ? any thoughts on this?

 

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12 hours ago, Simon2.4 said:

Watertight??

hopefully...

Let hope! How do you expect to get it out once it is siliconed into place?  Is Silicon the best option here? I'm honestly not sure how well silicon will adhere to part, or the rapid expansion of the hot-end during heating. Is there any way to accomplish a seal using compressive gasket instead? I may be off base but maybe some tube of car engine gasket material would be better suited for the heat than silicon.

I am curious once it is up and working how much the additional weight will affect performance, but specifically a how a fluid weight will act on the carriage, kinda concerned about untested vibrations. BUT only one way to find out!

Neat idea, excited to see how this evolves!

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20 minutes ago, Demosth said:

How do you expect to get it out once it is siliconed into place?

the waterjacket and E3D heatsink will become a single part that I can swap out for the air cooled normal one. Those heatsinks are cheap.

20 minutes ago, Demosth said:

Is there any way to accomplish a seal using compressive gasket instead?

Yah, that was my first idea like an O-ring stuck between the fins and shroud... O-rings are deceivingly complicated lol I wouldn't know how to find "the right one"

as for actual gaskets, they require mechanical compression to form proper seals, so screws and flat faces...

Silicone seemed like an easy solution, it has good thermal properties, and conforms to movement but better than silicone would be something like windshield urethane but that stuff is a pain in the a$$ to work with

At some point I might just try my hand at designing a custom water-cooled tool head rather than a 'bolt-on' mod. I just discovered how accessible SLM printing services are so at his point, the limit is my imagination, and ability to CAD

This will be my first try so as you say,

19 minutes ago, Demosth said:

only one way to find out!

 

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27 minutes ago, Demosth said:

I am curious once it is up and working how much the additional weight will affect performance, but specifically a how a fluid weight will act on the carriage

Water-cooled heads is not something new and this is a very small volume of water in the print head , maybe 4 or 5 grams. The shroud its self weighs 36 Grams if made of SLM stainless steel or 12 grams if made of MJF nylon. That's pretty heavy indeed and will be a compromise for sure.

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Noble idea, but there are a WHOLE BUNCH of things to factor into the equation.

First of all, unless I'm looking at your sketches wrong it seems you will be immersing the heat sink (fins and all) into the coolant. This itself will add complexity and not necessarily remove as much heat as might first be thought. The thermodynamics of such a setup will result in uneven heat transfer from top-to-bottom, potentially resulting in inconsistent results based on printing speeds, material, etc.

Since you are going the route of outsourcing the production of the jacket, consider designing a cylindrical heat exchanger to take the place of the original heat sink. Spiral counter flow, with the cooled fluid entering at the bottom and progressing upward will result in even thermal transfer the entire way. Flip the flow around and you'll be inducing a lot of thermal shock at the top - something that could lead to premature failure. You'll have to experiment with flow rates and potentially add a small surge tank to account for expansion/contraction of the fluid as it heats and cools. As for heat exchanger material, Copper is roughly 10x more thermally conductive than SS and designing a single-piece heat exchanger virtually eliminates leak potential. It will be relatively small and light weight so material cost won't be much of a factor. You could print an insulating jacket for the outside yourself, but internal heat exchange is where the rubber hits the road on this concept. Do a little digging and find articles on printed metal heat exchangers - lots of research going on there.

 

Best of luck and keep us tuned in!

 

Edited by Todd
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16 minutes ago, Todd said:

consider designing a cylindrical heat exchanger to take the place of the original heat sink. Spiral counter flow, with the cooled fluid entering at the bottom and progressing upward will result in even thermal transfer the entire way.

Yah, just make a complete replacement that fits in the E3Dv6 holder would be nice and safe and easier to get watertight. The heat exchange requirements are pretty low: I would estimate around 10 W so this is really non critical in that regard.

I started the whole thing thinking about retro-fitting existing E3Dv6 parts but as you say if I'm going to get metal 3D prited parts done, there is no good reason to use that heatsink in the first place...  

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its looks a very cool idea, but I think you need to solve those first

1st thing - you have to find some solution to watertight it, with silicon or rubber bands or some other way.

2nd thing - get a better orientation for the exit tube. - positioning the intake tube and outtake at the same height can cause some pressure issues, (I'm not an expert on fluid dynamics, but I see this principle on every liquid system I saw) 
at the current drew we see that water are coming into the chamber will try immediately get out so the water at the bottom will get less flow and will boil or be very close to this temp. that will add extra pressure.

Good Luck 

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1 hour ago, Todd said:

Presently in Paraguay doing some "work" for the US embassy.

Where did I leave my tinfoil hat? It'll all end in tears as the agency hunt Simon down for the missing [particle accelerator] plans uploaded to TeamFDM......

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@Simon, Here is what I had in mind. It's a plate heat exchanger designed to fit in the same cavity as a Phaetus Dragon heat sink. External dimensions are 22.5 dia. x 25.75 length. Still a few minor touches like the threaded holes on the top to secure it to the mounting frame, but the idea is to replace the entire heat break with this unit. The fittings on the top are sized for 1/4" I.D. tubing, which is easy to source. Printed out of copper with wall thicknesses of .5mm will make this not only thermally efficient, but convenient to mount and use.

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In case it isn't clear, the three "castles" on each side of each internal plate have holes through them and slots on each end for coolant flow. Basically, coolant enters from the top then goes straight to the bottom where it begins picking up heat along its journey to the exit at the top on the other side of the perimeter. Adding a small 12/24 volt pump, a printed (likely ABS) expansion tank with a slight air charge (3 - 5 Pa maybe?) and a small radiator, all to sit in an enclosure on the top of the printer's enclosure and you should be all set to go crazy with heating the enclosure (separate mod) and not worrying about causing jams.

Edited by Todd
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ok @Todd that's really nice and this would be ideal for sure. Here's why I'm designing the way I am:

- Stainless sucks for heatsinks but it's the only metal offered by JLCPCB. There may be better options for getting this done but I don't know any

- I want to maintain a certain flow through the block: my printer is very big and the coolant will have a long run to do to get to the block; I don't want the coolant to pick up too much heat in the chamber before it gets to the block. My chamber operates up to max 65c for now but I'd like to get it to 70-75. So the block needs around 16mm2 cross section flow the whole way through.

-SLM metal printing is more limited than I thought there are design constraints very similar to FDM : https://www.materflow.com/en/design-guidelines-for-metal-printing/

-Requirements are not very high for the actual cooling, I estimate 10w so I can can keep things small and simple.v4cut.PNG.5595ad794ed1a5736c5ceec38dad1158.PNG

So here's V4:

v4.PNG.39d66048ec8c169f019f4d0014d29827.PNG

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I got a late quote

Thought I share this one just for lulz... 2 issues and a funny joke

1-they convert the stl to inches and than talk about tolerances in their communication in inches

2-the tolerances they ask for the model (0.060") is inconsistent with their own specification (0.018) that's 5 to 1 , not just a nuance..

3 see if you can spot the big fat ugly joke.

lol.thumb.PNG.a7741de67d440197e8fea3e190dc8cac.PNG

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Hmmmm...it's way past my bed time but I'm guessing it's either the fact they just filled your name and address using crayon black squiggly lines or everything is up in the air (we can change the price, delivery time, anything....basically it's not worth the paper it's written on even as a ROM). Did it self-destruction after you read it?

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  • Simon2.4 changed the title to Watercooling the Printhead

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