Sometimes while fitting the flange onto the lens board, I ended up cracking the wood while screwing the brass screw into the bore pilot hole.

Dry Brass flange screw fitting had cause the cracks!

This could be caused by various factors:

The wood is brittle; pilot hole too small; the screw fitting is too near the edge and have many weak spots;the angle of the screw skewered while screwing, the lens board too thin and so forth.

When the lens board cracked, it’s either make new one, or just patch up. I decided the latter with ugly black duct tape solution

One tip I got from my woodshop tech to prevent or to reduce this incident is to apply beeswax onto the screw before screwing it in.

After drilling the pilot hole, take the screw and dab it into the beeswax
Wipe the excess beeswax off, and screw it in gently into the pilot hole