Roots blower

My hot end has an air ring around the nozzle with the air fed through a silicone tube from a remote pump, I have been using an aquarium pump but this cannot easily be controlled by the G-code. After spending some time looking at what was available I decided to make one.

The normal axial fan is not an option as it can't push much air through a thin (6mm bore) tube. Centrifugal fans are a little better, but one to give the required pressure would have deep blades like a turbocharger compressor and balancing becomes a problem. Piston and diaphragm pumps deliver more pressure than needed but at too small a flow - they are also noisy. The Roots blower is a good all round solution.



The completed Roots blower pump



Rendering of the CAD files



Rotors and body from an earlier try - clearance between parts was too large



The Roots blower working. Delivery is 15 l/min (0.5CFM)and maximum pressure is about 0.8kPa (3.2" of water)

For this to work well the printer needs to be very well calibrated - It wasn't but now is.

Mike

Very nicely done!
Can you show a photo of the print head arrangement?

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

Hopefully these will give the general idea. Please do not try Tekapeek (graphite loaded PEEK) shown in one of the diagrams - it was an abject failure.

View on bottom of hot end on a Mendel Prusa


Section showing parts


Section showing area fan/heatsink cooler


Edit: I have been looking for any photos showing the ducting, but the closest I have is a Youtube video. The silicone tube is clearly visible but the cooling was an older and inferior type.
[www.youtube.com]

Mike

Edited 1 time(s). Last edit at 11/27/2014 04:30AM by leadinglights.

Thanks!
I had never heard of cuttlefish bone, or as insulation. Fascinating.
I'll be following your progress.

I reported on my experiments with cuttlefish bone in [forums.reprap.org]

Briefly though: Cuttlefish bone is an exceptional insulator and can take the maximum temperature of any credible plastic extruder. However, it is very fragile. I use thin brass shim to build a protective box around the cuttlefish bone.

Mike

I have just dropped the STLs and instructions for this on [www.thingiverse.com]

Mike

This looks like a very nice idea for sure!
thanks for documenting your work here -
will look into it and try to adapt to my prusa i3.

my normal fan-cooling results in too much cooling down of the hot-end, since the air flow is not guided enough.

Alex

Edited 1 time(s). Last edit at 01/03/2015 07:49PM by Alexander1984.

Nice job! Maybe I'll make one soon