Author Topic: Seed winnower - fan advice.  (Read 85 times)

gmuller

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Seed winnower - fan advice.
« on: 2019-02-11, 02:50:06 PM »
I'm upscaling my portable small-volume seed winnower.  I need to process larger volumes, but still want it benchtop scale and portable. I currently use a motorcycle battery driven computer fan and electronic controller on my little batch processor shown below. I'm making it a bit larger, using wider boards for the baffles and increasing hopper size, and incorporating a few mods. I'm going for a 80mm computer fan, which fits neatly inside my 92mm pre-finished boards.
But my main problem is how to regulate fan output.
I can aperture-limit the input air, or aperture limit the output air, but will this have consequences for motor life or air flows?
Is there a cheaper alternative to the expensive electronic controller I'm currently using (which is problematic at low outputs - doesn't overcome the fan inertia)

I need portable, practical, robust, simple - probably not arduino, Andrew :)
GM

B. Copping

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Re: Seed winnower - fan advice.
« Reply #1 on: 2019-02-11, 10:53:08 PM »
Oh dear, I think Iím going to have to build myself something similar.
I see you have a proper set of plans...may I inquire about your source?

As to the fan dilemma...
I donít really have much experience with fans that small...
I would suggest regulating the air output rather than input.
Any Ďexcessí air will have several avenues of escape, assuming that the seed drawer at the bottom has not been made airtight.
Try cracking the seed capture drawer open a bit and see if that will regulate the air pressure enough for those seeds that need a lower volume of air (Itty bitties). Try opening the drawer by different amounts.
If that works, just add a small baffle to make sure that all your seeds hit the drawer.

I suspect that restricting the input will wear out your fan faster, and possibly cause irregularities in the air flow.

I can think of other low tech ways of regulating the wind, but none of them qualify as simple.

Doro

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Re: Seed winnower - fan advice.
« Reply #2 on: 2019-02-13, 06:33:01 AM »
This reminds me that I have to build a bigger one too :)
I'm using an old hairdryer as a fan. It has 3 stages which usually is good enough for most seeds.
I have also seen battery driven camping hairdryers, just using it on cool setting should give reasonable battery time.

gmuller

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Re: Seed winnower - fan advice.
« Reply #3 on: 2019-02-15, 03:54:36 AM »
Oh dear, I think Iím going to have to build myself something similar.
I see you have a proper set of plans...may I inquire about your source?

I just winged it from some online canary seed cleaners i saw on you tube.
Here's my contribution. I can take a scale photo if it would help, but i think the youtube vid is a good starting point.
https://www.youtube.com/watch?v=15GsruCkPXA
GM

B. Copping

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Re: Seed winnower - fan advice.
« Reply #4 on: 2019-02-18, 03:50:48 PM »
Nice!
Thanks for posting that!

What mods are you thinking of adding to this design?

gmuller

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Re: Seed winnower - fan advice.
« Reply #5 on: Yesterday at 05:00:04 AM »
I've worked on it over the weekend.
Mods are - shift from 60mm board to 92 mm board. Twice the height and width. much bigger hoppers and collectors. I thought a standard computer fan would fit the board width better than a blower fan, but the output seems to a bit too zephyr-like.
I've gloss-sprayed the inner surfaces to reduce friction, and after mock up will be over screwing the front and back face to reduce seed collection gaps and air leaks.
I've tried a hinged air splitter rather than an electronic speed controller for the fan - I had to go and buy a higher capacity fan, then found that stacking the two 80mm fans i had upped the exit pressure sufficiently. oops, had already purchased a 90mm high output fan. The hinged output air splitter doesn't seem to work that well, gauged with an electronic airspeed indicator i borrowed from work (we use them on our sea kayaking trips). I'm going to re - modify it and mount the fan on a sliding board to vary in the input air volume. I'll post some pics when i'm done.
GM