Author Topic: Seed winnower - fan advice.  (Read 556 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: 2019-02-19, 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

spacecase0

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Re: Seed winnower - fan advice.
« Reply #6 on: 2019-04-07, 09:15:43 PM »
I get that you have a mechanical solution all planned, but...
so you are likely using a 12V DC brushless fan,
they change speed with voltage. They run for years at lower voltages at reduced speed. I do this for my seed drying setups to get longer life from the fans and not to blow the seeds away.

not sure what you are powering it with, but if it is adjustable, just turn down the voltage.
motor speed controllers are unlikely to work well as they are pulse width modulation and do not change voltage.

if you have a regular power adapter you are using, all you need is a voltage regulator to slow down the fan, an adjustable LM2596 regulator board is efficient and works well for slowing down fans like that (I have done this many times before). They are for sale at amazon or ebay for not much (will post link if you want). if you are using this solution, you likely want to power it with about 14V from your power adapter and then down the fan speed with the regulator, this will give you the entire fan speed range with continuous adjustment and no risk of hurting the fan. if you start with 12V from your adapter, you will not be able to turn the fan all the way up to 12V, but it will still work.

another solution is to use diodes, each one drops about 0.7V, so just put a few in series (all pointing the same way, if it does not work, turn the diodes all around the other way) and try connecting at each point between the diodes till you get the speed you want, the down side is that there are steps to the speed and not continuously adjustable. Diodes to get are likely the 1N4001, they have a 1 amp limit, but are very low priced. I can also post a link, but don't want to in my first post on this forum.

gmuller

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Re: Seed winnower - fan advice.
« Reply #7 on: 2019-05-15, 09:20:47 PM »
Thanks for the info SpaceCase. I will check the voltage regulator route. The Diode idea sounds good - a multi stage rotary switch switching between the diodes would do for on the fly adjustment.
After a bit of fiddling around with the fans, I found even with good seals and stacking the fans that I wasn't getting the airspeed i needed to separate big seeds and debris. A 12 volt hairdrier might be the go. Or the original blower fan I had in the small model seemed to blow harder.
g

Olaf Nurlif

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Re: Seed winnower - fan advice.
« Reply #8 on: 2019-05-16, 10:27:13 AM »
I'm sorry if this has already been mentioned but I don't have time to read the whole thread.

Do you know the plans for the "Real Seeds (UK)" Seed Aspirator?
http://www.realseeds.co.uk/seedcleaner.html

You can use a vacuum cleaner as a "fan".

I built one and it works very well, even though I am not a very good woodworking human and it looks a bit crooked. I also used the wrong wood, it was too soft, I have to build a new one that is more exact and prettier.

spacecase0

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Re: Seed winnower - fan advice.
« Reply #9 on: 2019-05-16, 10:43:19 PM »
the reason that 2 fans stacked is not working is because the 2 sets of blades are spinning the same direction,
you would need a stationary intermediate set of blades that are angled the other direction between the 2 fans.
I have seen them built like that before, but even with doing that, not sure how well it would work for you.

gmuller

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Re: Seed winnower - fan advice.
« Reply #10 on: 2019-05-18, 10:43:21 PM »
I'm sorry if this has already been mentioned but I don't have time to read the whole thread.

Do you know the plans for the "Real Seeds (UK)" Seed Aspirator?
http://www.realseeds.co.uk/seedcleaner.html

You can use a vacuum cleaner as a "fan".

I built one and it works very well, even though I am not a very good woodworking human and it looks a bit crooked. I also used the wrong wood, it was too soft, I have to build a new one that is more exact and prettier.
Yep, I built one, -  works OK, but it means i have to access 240V, and get the vacuum cleaner out every time - a battery powered lightweight system that I can use anywhere is my preferred option.

gmuller

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Re: Seed winnower - fan advice.
« Reply #11 on: 2019-05-18, 10:49:32 PM »
the reason that 2 fans stacked is not working is because the 2 sets of blades are spinning the same direction,
you would need a stationary intermediate set of blades that are angled the other direction between the 2 fans.
I have seen them built like that before, but even with doing that, not sure how well it would work for you.
I stacked the fans with a 'director' box with internal fins (pointing straight ahead) between the fans, and also tried them stacked directly on top of each other - wasn't much difference between the two set ups,  it gave a boost to exit speed, but still wasn't enough to do a great job on heavier seed.
I think i will go up to a 120mm heavy duty computer fan that has a 5X CFM rating.
Bit busy at the moment, so will try it when i have a bit of down time.
gm

Olaf Nurlif

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Re: Seed winnower - fan advice.
« Reply #12 on: 2019-05-29, 02:40:15 AM »
Yep, I built one, -  works OK, but it means i have to access 240V, and get the vacuum cleaner out every time - a battery powered lightweight system that I can use anywhere is my preferred option.

You could use a akku or battery powered vacuum cleaner though.
It might be not that light weight any more then, so...