Re: Improved fan shroud / nozzle
Interesting design on that cross-cooling nozzle. I'm interested to see how the 40mm fan version works out.
I'm using your previous semicircular version and it's working out great with the 50mm blower, although my blower is slightly upgraded over stock (because stock broke). Delta makes one that's a drop-in fit, just slightly more CFM, real bearings instead of bushings, more solid all around and a little bit louder.
Re: Improved fan shroud / nozzle
@Tom
Glad it's working out for you man but I have to tell you, it does suffer from sag after a 48 hrs ABS print. And as the replacement blower I got is loud in a way that bleeds my ears, I stopped working on that version. The dual head aka Amphi (as in Amphismaena, Greek myth two headed snake) has held up very well and seems to work better than Surround version for aft cooling.
- - -
A note on Surround v1-v3 vs. v4.
v1-3 is 20g while v4 is 16g due to internal hollowing and mass reduction. Side-up v4 unfortunately suffers from vent droop (aforementioned torture test) that renders part trash, bottom-up version of v4 is far more stable after torture with 1mm or so sag of whole left arm that sanding can solve.
Amphi for 50mm blower is stable at 250°C up to 10 hrs so far. Notes on weight of designs so far.
Weights with hardware.
Surround v1-3, 20g + 27g fan + 3g 2x20mm bolts = 50g
Surround v4, 16g + 27g fan + 3g 2x20mm bolts = 46g
Amphi prototype = 23g + 27g fan + 3g 2x20mm bolts = 53g
Twin40 prototype = 30g + 23g fan + 6g 4x25mm bolts = 59g
Below is actually a failed print. Magigoo layer was two prints old, poor choice for an overnight print. But it survived with negligible warping on aft duct arm.
The bubble are my fault, tried to heat gun dry after fresh Acetone dunk to smooth ducting. Won't be doing that again. Will be my daily driver as soon as 2nd NF-A4x20 FLX arrives.
MK2S kit owner since 8/15/2017
Re: Improved fan shroud / nozzle
This looks awesome. Will you publish the Radial-Amphi files at thingiverse ?
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PRUSA MK2
- Noctua fan 40mm
- MK2/MK3 hybrid extruder
Re: Improved fan shroud / nozzle
Hi, this design also looks good.
I've printed the surround model but never had time to test it. It seems this design is better, but why didn't you design it with the fan in the same position of the original fan ? I know it's to prevent it from touching the extruder motor, isn't it possible to design it with a lower profile ?
It seems to me that this model also need the truncated extruder cover ?
My youtube channel about the Prusa I3 MK2 https://www.youtube.com/channel/UCz-zQZcKcvEDdd9C9hOKYWg
Re: Improved fan shroud / nozzle
@Cyrille
Benefits of tilted design.
Drawbacks of tilted design.
The truncated cover should be considered de rigueur for any duct modding as trimmed area is completely useless if stock nozzle isn't used.
I think I covered everything.
I've posted purely because someone asked me to. It is my new daily runner but want to dig out my eardrums when 100% fan speed. If NF-A4x20 FLX wasn't completely out of stock in the universe, I'd be using that weird Cthulhu design above (I call it Twin40 because ®).
MK2S kit owner since 8/15/2017
Re: Improved fan shroud / nozzle
Try this.
Don't know if I have taken enough off, and it is very rough...
Peter
Peter, that part looks fantastic. I think it will be perfect to fix my overhang curling issues.
Do you have a Thingiverse account? Can I post your part on my Thingiverse account with a reference to your post here?
Cheers
EDIT: It's not perfect (I still have some overhang curling issues), but this part provide outstanding improvements. I'm impressed!
Re: Improved fan shroud / nozzle
Yup, Amphi is live.
Linky no worky for me. Tried searching on Amphi too with no luck.
Taken down for more tweaks?
Re: Improved fan shroud / nozzle
Taken down for more tweaks?
Opps, I moved my stuff to Part Nozzle Amphi (for-aft). YouTubers I respect feel Thingiverse is a wretched hive of scum and villainy. MyMiniFactory favors the creators they say, also I'm not a fan of Makerbot/Stratasys who own Thingiverse leaving it to rot on the vine, they say.
But I'd recommend you don't use the Amphi. Off angle mount chews through cheap blower fans by the month!
MK2S kit owner since 8/15/2017
Re: Improved fan shroud / nozzle
Peter, that part looks fantastic. I think it will be perfect to fix my overhang curling issues.
Do you have a Thingiverse account? Can I post your part on my Thingiverse account with a reference to your post here?
Cheers
EDIT: It's not perfect (I still have some overhang curling issues), but this part provide outstanding improvements. I'm impressed!
It works fine for me and that's all that matters. I don't upload models to Thingiverse; feel free to do what you want with it. You will need to attribute the original source, not me.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Improved fan shroud / nozzle
I've found NF-A4x20 FLX to not meet my requirements due to its relatively high kickover current. I should have realized that FLX variant has no listing for minimum RPM unlike the PWM version which is 1,200. FLX on the other hand has 3,700 as documented minimum value which lines up with my testing with kickover of 61% which safe kickover at 65% when considering both fan's max 5,000 RPM. This means PWM can do 24% theoretical minimum with a current-control to PWM adapter vs. FLX's 62% min. This is the difference between a melted printer vs. warped printed part. Can't recommend NF-A4x20 FLX as a part cooling fan if printing anything other than PLA and maybe PETG. ABS or higher is out of the question due to thermal runaway vs. melting your printer.
So yet another part for my bucket of ABS glue (used to be a cup).
MK2S kit owner since 8/15/2017
Re: Improved fan shroud / nozzle
Hi all,
Time for better parts cooling!! I've read through this post and see Peters mod looks like the go to for a direct bolt on for the MK2.
Is this the consensus? Going to print later and see how it goes.
Re: Improved fan shroud / nozzle
Peters model worked for me
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Improved fan shroud / nozzle
Peters model worked for me
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Improved fan shroud / nozzle
Thanks, going to give it a try later. Wish we had an option that gave a little better visibility!! I guess I better print it and see first though!!
Re: Improved fan shroud / nozzle
PJR
I'm looking at improving my bridging and have success with the shroud you designed/ redesigned.
However I do have one issue:
If I do not manually change the fan speed, I run into Thermal Overrun issues every time, even at higher Z levels.
Do you have any suggestions for fan speeds to use or where I should be adjusting that.
MK2
Slic3r 1.37.2
(fan speed is running at 221, above 1st layer)
Any pointers would be appreciated.
Re: Improved fan shroud / nozzle
Maybe my conservative Thermal Runaway avoidance chart can help.
Sock will also help adding about 40% more fan to below.
Thermal Runaway avoidance chart.
Hot-end Fan Hex
200°C 100% 255
210°C 85% 217
220°C 70% 178
230°C 55% 140
240°C 40% 102
250°C 25% 64
260°C 10% 25
Manual fan minimum dead start value:
New firmware seems to kick start fan so you may need to update for your specific fan.
MK2S kit owner since 8/15/2017
Re: Improved fan shroud / nozzle
Very cool.
That gives me a place to start. Using Slic3r I'll play around with Filament setting and see if I can find the mid point between better bridging and avoiding thermal issues.
Side question, since the shroud is intended to cool the plastic and not the hotend, would modifying the shroud to avoid the hotend entirely work?
Or is there so much airflow and turbulence off the print that it won't matter?
Re: Improved fan shroud / nozzle
Pretty much. It is why socks sell well. My hope is E3D makes an insulated block someday because they seem to be into elegant solutions which a sock is not. Maybe a copper block wrapped with Zirconium Oxide shell? Wouldn't be cheap but I'd grab one.
MK2S kit owner since 8/15/2017
Re: Improved fan shroud / nozzle
I'm currently using this one with pretty good results: https://www.thingiverse.com/thing:2471337
Yeah, pretty similar.
I did find my model, so here it is. Needs a little cleanup after printing.
Peter
I made a duct heavily inspired by yours but with the arms wider, without sharp corners and with an internal rib to guide the air. It is designed on the basis of how flow-optimised ducting usually looks like but no CFD analysis has actually been done on this part. 
Since air is a compressible but low-viscosity fluid, sharp corners contribute more to pressure drop than distance traveled and because of this, I've made the arms very long but with much more smooth bends and with an internal rib so there's 2 "ducts" guiding the air around the corner.
It's probably overkill, but I like it that way since the mass is neglectible. 😀
I can't publish my thing on thingiverse until tomorrow, but then it will be public here: https://www.thingiverse.com/thing:2718093
Untill then, it can be found at https://www.dropbox.com/s/ianrelr6zvo2a8z/fan_nozzle_V3_upright.stl?dl=0
Hope you don't mind that I was so inspired by you but otherwise, I'll take it down as fast as I can. 😀