Really basic stuff

Gents; Just a few questions on basic construction.

1.RPM range of drill bit for drilling stacks of wing ribs?
(2300)?
a.Favorite type of drill bit for drilling thru the stack
of wing ribs? (brad point)?

2.What speed setting and teeth per inch on blade is
favored for cutting? (1800spm,14tpi)?

Thanks Steve D.

Balsa does not drill well. The best thing to make holes in balsa is a piece of brass tubing sharpened on the inside with your #11 blade and then nicked with the same blade to make it a little saw like. There is some kind of specialty bit you can get but I think it is big bucks. Make a jig or template and do one rib blank at a time, then put rods or bolts or whatever through to hold them in a stack. It goes pretty fast.

I dunno, I disagree a bit with Jim about drilling balsa. For my money, if the stack is clamped tight, the drill bit is new and sharp, and the speed is fast enough, the holes are plenty good. I run my drill press at max-without looking, 2300 or so sounds about right. Advance the drill very slowly and smoothly. I use the tubing trick a lot, just not here. Experiment and see what you like best.

A forsner (not sure on the spelling) is the way to go. Unlike twist bits and brad points they cut from outside. Let the drill press spin as fast as it will go. Second choice would be the tubing as described above - sort of a forsner bit without the point. They can be expensive in the local hardware store - if they have them at all. Best bet is one of the woodworking mail order folks.

Steve, Steve, Steve...

Don't complicate things. Just take whatever speed your drill press is set on, and drill away. Balsa is fairly tolerant to a wide range of drilling speeds.

The important thing is to have your rib stack aligned exactly so.

Same thing with your saw speed. Just have at it. Worry about something else, like global warming, or your deadbeat brother in law, or something.

Yeah, I use the old sharpen-a-piece-of-brass-tubing-and-strike-it with-a-hammer trick once and a while. But this is with small pieces, or dealing with onezies and twozies. Does work well. Smack the brass tube about three or four times with the hammer, angling the tubing a bit differently each time. And don't even bother getting the "holes" out of the tubing.

I agree with Currell on most of his comments but the tubing thing REALLY works well when you spin that like a drill. I just soldered a piece of solid rod into the end of the tubing (I used Stainless tube cause its stronger-and hit it with a tig gun) but brass works ok too. Then cut a couple of slots about 1/8" long up the side of the tube for "teeth"

I think I also heard this slot cut Idea from one of the West Coast gentlemen. It works alot better than any other drill ive tried and alot better than punching the loles thru an entire stack of ribs.

This of course is aimed at alignment jig holes of perhaps 1/2: dia or less.

In theory it will work well for larger holes but is harder to construct. Large forstner or multi-spur bits are expensive.

All these ideas sound right, but I make the end ribs of the stack from 1/16 birch ply. This prevents the bit from tearing up the balsa when it goes in and when exits the bottom of the stack. i.e. the plywood may chip or tear a little but you don't care about that rib anyway. The plywood also slows the sanding processes down a little so its harder to take off too much too quick. Keep the stack tight. I also make a couple of extra ribs in the stack if possible, that way I have a perfect spare in case of an accident.(during building and after) Best of luck.
Bob

I also tried something on my last project that worked very well. After sanding and finishing the shaping of the rib stack, I applied a couple of dope coats and a couple of filler coats to the ribs. it filled all the little die cutting divots along the edges. (may not be a real problem on scratch cut ribs)

THen I used a razor knife blade to "cut" them apart.

THe result was beautifully square and smooth ribs that show really well through the covering. Almost looks like 3/32 wide rib caps were applied!

probably not new but Thought I'd mention it.