tfgreen

Good morning!

I'm starting my first plans-built project (for which I drew the plans), and I'm having problems drilling clean holes in balsa sheet. I'm using a small bench top drill press, and new drill bits. I've trid each of the 5 speeds available on this press (3050 rpm - 570 rpm) with similar results - holes with torn edges.

Any suggestions?

Thanks,

Tim

paero-RCU

My Feedback: (14)

Don't know how big you are trying to go, but for most sizes up to about a half an inch, I use brass tubing. Just sharpen the edge and you can do it by hand. If the balsa is thick or you have a lot of them to do, they use the drill press, But you have to remember to clean out the inside of the tubing after a few holes.

Larger than 1/2 inch I'd consider a hole saw.

Vince

My Feedback: (1)

About the only way to get clean holes with conventional drill bits is to sandwich the balsa between two pieces of hardwood, and drill through the whole mess. The sharpened brass tube mentioned previous works well.

Vince

Cactus.

My Feedback: (1)

the brass tube method is great and for anything bigger you can buy a compass type with a blade that cuts a nice clean circle for you

CurtD

My Feedback: (1)

There are two ways to accomplish this that I can personally attest to. If you're trying to drill a single piece or maybe two pieces stacked then a Forstner bit will cut a perfect hole. It does not work well with more than two or three sheets stacked, however, since Forstner bits are not particularly designed to be self clearing.

If you want to drill cleanly through a stack of balsa sheets (like holes for jig rods in ribs) then go to any hardware store and pick up a brad-point drill bit of the correct dimension. These work similarly to the Forstner bit except they have a spiral twist and will clear themselves better. When drilling, use a backing board under the balsa sheets and take it slow. I highly recommend a drill press for best accuracy and pull the bit back frequently to clear the chips that collect in the hole.

Good luck and HTH.

Al Stein

Another way to deal with making small holes cleanly is to use a dull bit and run it in reverse. It grinds away the wood instead of cutting it out.

Most of the problem with drilling balsa is that it cuts too easily, so the sharp, clean, self-clearing flukes that make a drill great for most other woods just make it grab and tear in balsa.