Need dimensions for making cresant and bat wing cresant

[Stephen Thomas]

Need info on making these type of openings. I have been looking on the internet but have not found any help. Any help is appreciated.

Thanks,
Steve Thomas

[Emil Pampell-Tx]

Steve, the critical dimension is at the center of the opening on both. It should be 1-3/16in. I bought a forstener bit that makes a hole exactly that size on the internet for about 5 or 6 bucks plus shipping. I use a drill press, but my neighbor uses a regular hand held drill.

The crescent is the upper part of a 3in circle (go down 1-3/16 in from the top

The other can be made nearly anyway that you desire, as long as the pips are at the bottom. I drill 3 holes, side by side, that are 1-3/16in, it makes an entrance about 3in wide.

I would very strongly recommend a forstener bit, and then you could be assured that the hole is the correct size, as the opening size is very critical. If its too small, the martins cannot get in, if its too large, the starlings can get in.

good luck

[Stephen Thomas]

Emil,

Thanks for the reply. I knew the center needed to be 1 3/16 inch. But I thought it looked like the two outside circles were something smaller. Then what was left you drew tangent lines connecting the the circles and cut rest of it out with a fig saw.

I presume after cutting 3 1 3/16 holes with approximately 3 inch wide you would have to round the two bottom tabs off. Do these tabs at the bottom have to be a certain height from bottom of hole to top of the bat wing tab?

Thanks for your reply.

Steve Thomas

[Laverne]

Hi Stephen.

When I made my "bat-wing" excluders, I used a 1" hole saw or forstner bit for the two outside circles. The size of these is not critical because they are there to accomodate the PMs wings. I believe they should be smaller to prevent the PM from attempting to enter the side openings and getting stuck. The height of the tabs can vary. I made some in 1/4" plywood and they broke off to about 1/4" in height. They still worked at excluding the Starling. I would put a maximum height of these tabs at about 1/2".

If you want an exact pattern - you can purchase a single plate with the original bat-wing excluder in it. The PMCA sells them here in the PMCA Shop. That is what I did.

[Emil Pampell-Tx]

I usually round off slightly the bottom tabs, but I like for them to be 3/8in to 1/2in high. I make the top flat with my dremel sander.

Like Laverne sezs, the outside holes can be any size, as the martins simply need to get their wings in thru these side holes.

I rather see the top flat on any configuration. On the crescents, it seems like the martins have a harder time learning to get into them, probably because the top is not flat.

[Stephen Thomas]

Thanks to all that responded. This helps me to make the correct size hole. Had couple of visitors this fall. Hope to see them in the Spring.

Again thanks for the feed back.

Steve Thomas