Multi-material/multi-colour Active Mixing printhead (three materials) September 05, 2016 04:17AM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 05, 2016 05:14PM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 09, 2016 12:39AM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 09, 2016 08:02PM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 10, 2016 04:51AM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 13, 2016 02:21AM |
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frankvdh
Thanks for sharing.
I wonder whether a "rifled" nozzle, with helical grooves would get useful mixing without the complexity of moving parts? In your project research, did you find anyone who had done any experimentation in that area?
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dc42
Thanks for your work in this area! Your thesis is an interesting read.
My primary interest is delta printers, in which height above the print head is not an issue but sideways protrusion is. So direct motor drive would be preferred to using the bevel gears. Perhaps the heatsink could then be eliminated, especially if a thermally-insulating coupling is used to couple the motor shaft to the mixer shaft.
Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 13, 2016 06:38AM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 13, 2016 02:50PM |
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JamesK
The idea that keeps going around in my head is an electro-magnetically coupled mixing element. I have wondered if a low frequency drive signal for mixing could be used along with a high frequency for heating, so the active part does double duty as both a stirrer and an inductively coupled heater.
Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 13, 2016 02:59PM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 14, 2016 04:59AM |
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JamesK
Interesting points David. Possibly rotation isn't necessary, I was considering an iron billet that could be moved up and down, or perhaps side to side, in the mixing chamber. That should be easier to achieve than rotation, much like pulling the centre of a solenoid up. While rotation seems optimal, it may be enough to just get something rattling around inside the melt chamber.
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JamesK
The materials question is interesting. I'd rather assumed that enough magnetic field would penetrate a non-ferrous material like aluminium to still be effective, but I may be way off the mark there.
Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 14, 2016 12:43PM |
Registered: 7 years ago Posts: 4 |
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dc42
It depends on the frequency. I was assuming that quite a high frequency would be needed to get enough induced current in such a small rod, maybe 10kHz. The skin depth in aluminium is 0.8mm @ 10Khz according to the Wikipedia image at [upload.wikimedia.org].
It might be possible to put a large cap on top of the mixing rod to make it easier to induce current in it. Then the aluminium chamber block could have a disc cut out of the top to accommodate the cap, and a piece of ceramic or thin aluminium fitted on top of the block to seal it. Molten filament would surround the cap so the melt volume would increase considerably, but with any luck the filament in that area wouldn't tend to mix with the filament lower down because there would be no upwards/downwards movement of filament in that area in that area. If it is sealed well enough, there may also be a permanent air bubble there.
Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 14, 2016 05:05PM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) October 15, 2016 03:28AM |
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Re: Multi-material/multi-colour Active Mixing printhead (three materials) November 07, 2016 10:22PM |
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