My 6 input (5+1) mixing hot end
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@fma Yes, I've looked at the copper head and Slice engineering's liquid cooling designs too...(and every other "off the shelf" heat break that I can find).
My problem is that I have 6 inputs but only one output. With that type of heat break, the normal method of getting everything to seal is that the nozzle is tightened against the heat break. But I can't do that. So I need the heat break to have flats or a hexagonal section, so that it can be tightened against a flat plate. And it needs to be 4mm ID so that I can use a PTFE insert. So I'm having to make them. But they will look very similar to the heat breaks in the design you posted - just with flats or a hexagonal section so that they can be tightened.
Essentially, the cooling system and heat breaks worked well. It's just that I had filament leaks because press fitting the heat breaks into a flat plate didn't work well.
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@MrDui For info, this was my first attempt at the simpler "tubular" design
Despite copious amounts of sealant, I still had leaks.
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I don't know if they exist in such small size, but you may search for copper gaskets used on cars oil tanks: https://www.ebay.com/p/202950637
They are crushed during tightening, and handle high temperature.
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Did you see this one? It can be tighten with a spanner, but I don't know how torque it can handle...
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@fma said in My 6 input (5+1) mixing hot end:
Did you see this one? It can be tighten with a spanner, but I don't know how torque it can handle...
Yes I did. But it's "all metal" so only 2mm or so ID (internal diameter) and mixing hot ends need to have PTFE lined heat breaks.
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Ah, sorry, I forgot that point...
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@fma said in My 6 input (5+1) mixing hot end:
Ah, sorry, I forgot that point...
No worries - thanks for trying
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I'm wondering how these heatbreaks are made: are they just brut force-fitted?
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@fma said in My 6 input (5+1) mixing hot end:
I'm wondering how these heatbreaks are made: are they just brut force-fitted?
The Mosquito ones? I wish I knew. I've asked the question of Slice Engineering but they didn't answer - guess it's a trade secret.
To me, as an engineer, it's some sort of dark magic. The tubes are really, really, seriously, thin - very easy to bend or crush (I know from experience). So if they are press fit, then they must use a tool of some sort which is very good fit inside the tube to prevent it from crushing. Even then, I can't see how it can be a press fit. But the magic doesn't end there because they are stainless steel tubes, fitted inside a copper nut. Copper has a much higher coefficient of thermal expansion than stainless steel, so one would expect the tubes to come loose at high temperature but they don't. Maybe they use some sort of high temperature adhesive but there is no sign of any residue.
If I knew the answer, then it would reasonably easy to replicate using thin wall 4mm ID stainless tube which would take a PTFE liner, instead of the 2mm that Slice Engineering use.
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Perhaps by using hot crimping?
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@fma said in My 6 input (5+1) mixing hot end:
Perhaps by using hot crimping?
Perhaps. But the copper part of the heat breaks tend to change colour after they have been heated and there is no sign that has happened in the "as received" condition.
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They may cool down the stainless steel tube with liquid nitrogen...
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By way of an update if anyone is interested...........
https://www.youtube.com/watch?v=VQdoTJMsHGo
and
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it is alive!!!
AWESOME question, the acrylic "flow visualiser" with thermal probe - you made it or you purchased it ?
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@arhi said in My 6 input (5+1) mixing hot end:
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question, the acrylic "flow visualiser" with thermal probe - you made it or you purchased it ?You haven't been paying attention have you?
https://www.youtube.com/watch?v=Hai_zqtcauQ&t=145sand
https://www.amazon.co.uk/gp/product/B078PFRG74/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
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@deckingman said in My 6 input (5+1) mixing hot end:
@arhi said in My 6 input (5+1) mixing hot end:
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question, the acrylic "flow visualiser" with thermal probe - you made it or you purchased it ?You haven't been paying attention have you?
https://www.youtube.com/watch?v=Hai_zqtcauQ&t=145sand
https://www.amazon.co.uk/gp/product/B078PFRG74/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
I haven't watched it yet Ian but have you connected the Temp monitor to the Duet if not the Water-cooled PC guys do a sensor that is in fact a 10K thermistor which work quite well with the Duet.
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@Dougal1957 said in My 6 input (5+1) mixing hot end:
@deckingman said in My 6 input (5+1) mixing hot end:
@arhi said in My 6 input (5+1) mixing hot end:
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question, the acrylic "flow visualiser" with thermal probe - you made it or you purchased it ?You haven't been paying attention have you?
https://www.youtube.com/watch?v=Hai_zqtcauQ&t=145sand
https://www.amazon.co.uk/gp/product/B078PFRG74/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
I haven't watched it yet Ian but have you connected the Temp monitor to the Duet if not the Water-cooled PC guys do a sensor that is in fact a 10K thermistor which work quite well with the Duet.
You need to catch up too Doug
Short answer (as you haven't been watching my videos), is no - that sensor just happened to be bundled with the flow meter so I bunged it on the printer because why not? I will be fitting a temperature sensor of some sort that I can connect to the Duet for monitoring purposes. No point in controlling the pump speed as it's almost silent, so I'm happy enough with the current arrangement which is to turn it thermostatically when the hot end temp>50 deg C. But It might be nice to take some action via a macro/conditional gcode if the coolant temperature exceeds some pre-determined value. -
@deckingman said in My 6 input (5+1) mixing hot end:
You haven't been paying attention have you?
watched the video but missed that flow thingy the first time
.. probbly something distracted me .. and since I use very different water arrangement (submerged pump, long hard pipes - ones ppl use for pluming that you heat weld, heat exchanger, pump, 10m away from the device .. ) I did not pay too much attention at your pluming work as is too different from mine .. you have it as a single portable device and I kinda created some plumming in my work room that handles watercooling different devices.. but this flow visualiser looks interesting so I'm def. getting one -
@arhi said in My 6 input (5+1) mixing hot end:
but this flow visualiser looks interesting
so I'm def. getting one I wouldn't have thought that it would be too difficult to print or otherwise make something similar. My initial idea was to make something like a paddle on an arm that would sit in the coolant pipework and get deflected be the flow. The arm would then trigger a microswitch which would light an LED to show that the flow was healthy. But then I saw that flow meter thing and it was cheap so..... It's just handy to have a visual re-assurance that all is well with the coolant circulation.
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@deckingman said
Copper has a much higher coefficient of thermal expansion than stainless steel, so one would expect the tubes to come loose at high temperature but they don't. Maybe they use some sort of high temperature adhesive but there is no sign of any residue.
If I knew the answer, then it would reasonably easy to replicate using thin wall 4mm ID stainless tube which would take a PTFE liner, instead of the 2mm that Slice Engineering use.
- Copper and stainless steel have virtually identical coefficients.
- If the copper side is doing it job correctly, the junction of the two metals doesn't actually heat up much beyond room temp.
- Press-fitting stainless steel into copper is very easy, as stainless is much much harder than copper (which is basically cheese in comparison).
The trick is to design an assembly jig that both constrains the exterior of the tube and has an internal pin (as you say). That combination will prevent the tube from buckling or bending and it can be pressed in using an arbour press or whatever you have handy.
The biggest challenge is machining the copper, which is a pain.
Properly designed press-fits are a great way to build a hotend, you just end up spending a couple of hundred bucks on tooling up front.
