Pollen trap screen size?

[pistolpete]

I built a pollen trap a few days ago.  I used a fence of finishing nails set 1/4" apart for the screen.  I tried it on a hive for a couple of days and collected exactly two pieces of pollen.   So obviously my screen is not effective at stripping the pollen baskets.   Could someone with a store bought trap give me some insight on the screen size and design.

[robo]

#5 is the common size used

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[Barbarian]

I built a trap many years ago. It was a Canadian (?) design which went between the BB and the super. It worked but I didn't use it for long. I think I still have some of the s/s mesh in the shed. Let me know if you want me to root it out and measure. I think I found "ladders" in the trap useful.

[pistolpete]

I went to the local stores and nobody has any idea what #5 screen is.  Even phoned the metal suppliers for the feed store and they didn't know either.  I hope one of you guys could actually measure the screen size for me.

[apisbees]

Pollen trap plans designed at
THE ONTARIO AGRICULTURAL COLLEGE (OAC) POLLEN TRAP
To trap pollen, returning foragers must pass through some type of a barrier that will dislodge the pollen pellets from their legs. There have been many different designs over the years, but the OAC Pollen trap, originally introduced by the Ontario Agricultural College in 1962 has proven very effective. Its most attractive features include:
Less crowding of bees at the entrance
Drones can still leave the hive
Pollen stays dry and can be harvested from the rear of the hive without interrupting bee activity at the front entrance'
 
Go to page 9 http://www.agf.gov.bc.ca/apiculture/construction.pdf
2 layers of 5 mesh per inch hardware screen 1/4" apart is what is required to disloge some of the bees pollen from their pollen baskets.

[apisbees]

I get it from a small family hardware store Fisher's Hardware who is a Home Hardware affiliate. Because it is a size that is not stocked you will need to buy a roll most likely. Talk to other club members and you might get enough interest to build a few to make it worthwhile

[pistolpete]

Thanks for the Info.  I'll see if Home hardware has some.   My pollen trap fits over the front entrance, rather than under the hive.  The one you posted looks good, except you'd end up with all of the hive debris in the pollen.

[apisbees]

The bees try to remove the hive debris and drop it while trying to get thru the screen on the front mount ones also. I built a set of stacking screens the top tray used #8 and them had 2 more that got smaller with a cloth over screen for support on the bottom. I placed the pollen in the top and shook it and the bottom was dust the middle 2 had large and small pollen grains and the top had bee parts and large debris.
Pollen traps really congest the the bees entering and leaving the hive so the under mount was designed to give the bees maximum area to travel thru. For the beekeeper with his hives in his yard and can empty the traps often the smaller storage tray is not an issue, but if the pollen gets to stacked up it will mold fairly quickly. the under traps allow for more air flow and more pollen to be trapped and time between collection. 
the nice thing about the front traps is that you can easily move the trap from one hive to the next so you can trap continually with 1 trap and 3 of 4 hives.
Just some ramblings of some of the pros and cons. I have and use some redesigned OAC Pollen traps. The tray pulls out the front so it works with hives on pallets. It has a movable entrance block so the bees can enter the hive below the screen so pollen can be collected. move the bloke down and the bees can enter above the screen and not loose the pollen in their pollen baskets.