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robrps

Bear Extruder Part Cooling Duct (Updated to V2)

by robrps Dec 29, 2018
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Would this fit on the newer 0.7 bear extruder?

Rob, can you please upload a STEP file of your nozzle. I would like to do a simulation on it, but it doesn't work when I convert from your STL file. The conversion must be done from your Fusion file.

Sure thing, I've added it to this thing.

Hi ROB,
Unfortunately, it was not possible to do all the tests in the simulation. The program complained about the geometry and crashed when I tried.
But there is another method to test, but then I must have a solid STEP file as well. The solid is used to simulate the air volume inside the nozzle and it must have exactly the same outer geometry as the nozzle but no cavities.

Otherwise, you will be happy with these pictures. The pictures show areas where the air velocity is at its highest, ie. narrow passages. In those places where the flow is throttled, you should try to make the channels larger.

Thanks for the images - can I check two thing firsts. Has this been positioned based on the R3 Prusa extruder or the current 0.6 Bear extruder. I ask becuase it looks like the nozzle is too far towards the back of the heated bed. This is going by the 'ROB_Channel_middle.JPG' - the 3 'dividers/roof support' pillars should converge at the X0 and Y0 which on my model is the centre of the nozzle (using Greg's CAD model). I'd also say that the nozzle is also too low - again based on Greg's CAD the lowest part of the duct should be 2.5mm up from Z0 (in an ideal nozzle placement world).

That being said, I can't argue that I need to make some more room for the side inlets and if I'm reading it correctly the centre duct could do without the roof support.

Would it help if I sent you an X_T (Parasolid) of the duct, or even just the internal chambers (they were a Boolean subtraction from the main body)?

The nozzle is based on Prusa R3 and Bear because they have the same physical dimensions from center to back of the extruder (23 mm). The coordinate system you see in image "ROB_Channel_middle.JPG" belongs to the simulation program and can be moved where I want. In the CAD model's assembly, the origin is located in the center of the extruder.

And according to my CAD files, the distance from Z0 up to the bottom of Prusa R3 duct is 3 mm. My duct is 1 mm higher than Prusa original and the distance from Z0 to the bottom of the duct is therefore only 2 mm.

And yes, we can try with your X_T Parasolid as a STEP file. But as I mentioned, I get many protests from the simulation. It is probably the conversion between several CAD formats that makes it happen.

I've attached the Parasolid models to this reply - One of the files has the E3D hotend, nozzle and blower (from the Bear files) for a positional double check, the other is the Parasolid of the duct only. Last file is the internal structures trimmed off at the exits. Both NX and Rhino tell me they are solid bodies. Hopefully they will be simpler to work with. Thanks for doing this :)
P.S. Happy New Year

ROBRPS, I'm sorry but unfortunately I can't simulate the files. The program (Autodesk FDM) does not accept all geometries, and it crashes every attempt.
Happy New Year to you to...

Thanks for giving it a go - I'll download the trial of Autodesk CFD 2019 and see if I can get anywhere.

Thanks a lot Rob for all the hard work and for the remix!