Just printed the first print.

Hi Neil,
I am pretty sure the fans we use are 24 CFM. A crude test with a hot diode acting as an anemometer confirms it has a higher flow rate than a Gelid Silent 6 which I bought to compare. As it has the same dimensions and blade count, etc, I think the only reason it is a bit quieter is that it spins slower.

I can't see any reason why it would improve print quality unless your original fan was on its way out. I.e. not only noisy but also spinning slower than it should be.

I can also say that the centrifugal blower here: [forums.reprap.org] does have a higher air flow, but is also significantly noisier.

I will try to make a better anemometer to get some quantitative results to evaluate different fans and ducts.

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[www.hydraraptor.blogspot.com]

@nophead: I think that with the amount of noise the fan was making on occasions the fan was definitely on its way somewhere.

I agree there is quite a difference between 24 CFM and 16 CFM and, on paper, your fan is probably better. I do think though that the airflow from the shroud is not optimal for cooling parts. I know it is difficult to keep air away from the hotend while still being able to cool the workpiece but maybe there is scope for improvement there.

You really do have more time now, don't you?

Regards,
Neil

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Yes finally have time to experiment again.

The duct only really works with objects bigger than its inner diameter so it cools parts of the object laid down some time before. I have seen people use a jet that points directly at the nozzle. Not sure how that affects the bond strength but it would allow smaller objects and probably better bridges.

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[www.hydraraptor.blogspot.com]

Also keeping the flow away from the hot end is less critical now that it is insulated. The insulation could be improved with a couple more turns of tape and perhaps a piece stretched across the bottom.

In the past I made a cast silicone boot to fit a hot end of my own design but never tried it as I switched to J-heads. The mould and a core were printed of course and I measure the volume needed in netfabb and used openscad to generate custom sized measures for the resin and hardener in exactly the correct ratio and 10% extra volume.



Edited 1 time(s). Last edit at 11/10/2015 11:30AM by nophead.

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[www.hydraraptor.blogspot.com]

That was a good idea. Production-wise I suppose the silicon tape was a cleaner and faster solution?

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

I didn't try with J-head because the shape is more difficult. The PEEK insulator is bigger than the heater block, whereas my own design hotend uses smaller diameter PEEK to get less thermal conduction. I don't think I had considered kits at this point.

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[www.hydraraptor.blogspot.com]