I tried to get this information on an earlier thread but did not get what I need.
i need to drill an accurately positioned hole through cork, 2" foam and 1/2" plywood. This hole will be for the piano wire from the Tortoise to the points of the turnout. What type of drill bit would you choose? For example, a spade bit, or a twist drill or a brad point etc. I only get one chance so I don’t want to mess it up.
BB
I can’t help you there, but don’t let the bit get too hot or you will melt the foam.
Friction and heat builds on anything, wood, foam, etc…
How about using an awl to go through the cork and foam, then a bit for the wood?
the spade bit (or speedbore bit ) is to aggressive for the cork and foam and will tear up the foam. the twist drill bit will be the best choice followed by the bradpoint bit. you have to keep the bit going straight verticly and not let it drift.
I’ve had luck in the past with a holesaw. I used an old screwdriver that I heated up to start a pilot hole in the foam. Use a drill with a highspeed, if possible look for a holesaw with an extendable shaft.
The holesaw sounds good but where would I get one 1/8" or 1.4"?
BB
A hole saw would have one very slight advantage, maybe, and that would be to “cauterize” the sides of the hole in the foam…again, maybe, due to heat. I doubt it, though.
I have used simple twist-bits, in fact wood drill bits work very well. Personally, I use the one wood bit for the whole shebang, and it works like a darn.
-Crandell
a hole saw has to have a pilot bit, and I think it’d be hard to find one with a bit smaller than 1/8, which could make it hard to get one. Your best be will probably be a brad point, or just a good ol’ pilot pointed Dewalt bit. A whole set of these is really nice, because they drill everything quickly and cleany.
Greg
I don’t think you can get a holesaw that small. But perhaps you could use a forstner bit ? I’ve never had to drill a hole smaller than 1/4" you might want to experiment with different tools and options before attempting them on your layout. If you know where you need the hole underneath the layout I’d say use a spade bit to go through the wood first then cut the cork with an exacto knife, and finally run a long phillips head screwdriver (heated moderately) through the foam.
Why don’t you drill a 3/4 or 1" hole (or any size you choose), in a material of your choice that drills the way you want it to, glue it in place then drill through it.
I have to drill through the same - cork roadbed, 2" foam, and 1/4" plywood for my tortoises. I just use a regular old drill bit. Personally I drill 3/8" holes for the tortoise wires. 1/4" will do, but 3/8" doesn’t hurt anything IMHO.