Is there a logical reason for drill bits all being different lengths? When I want to drill different sized holes on the same piece of material, it is a pain in the neck because sometimes it changes the setup on my drill press. Are there sets of same-length drill bits? Thanks -- Daven
A small diameter bit has to be short to prevent it from whipping, buckling, and breaking when used. Larger diameter bits can be longer while retaining a satisfactory diameter/length ratio. Now large diameter bits *could* be made shorter. That would lessen the difference in lengths between small and large bits. But as far as I know, no one makes a set like that.
Yes. Bigger holes also tend to be longer holes. Also the rigidity of a drill bit is a function of its length/diameter ratio. The smaller the drill the shorter it needs to be to work without deflection. You can buy "stub" drill bits which are shorter and more rigid and designed for more accurate on centre work but the length will still vary with diameter.
Anyway, ain't no thang to work out in advance which is the longest drill bit you'll need for a job and make sure the machine has clearance for that length before you start.
You've already gotten quite a few good replies. But there is one thing which I don't see mentioned, so I'll plunge into that.
First off -- what is the maximum diameter which you actually
In the range up to 1/8", there are a series of drill bits made with 1/8" shanks, so the small diameter part can be appropriate to the diameter of the drill.
These also tend to have split points (so they are less likely to "walk" when starting a hole on a level surface, and are available to amazingly small diameters.
These are typically solid carbide bits (though the shank may be steel). They are made and sold for automated machines drilling holes in printed circuit boards. Since no printed circut board is very thick (I would be amazed to see one as thick as 1/4", even with multi-layer), the flutes do not need to be very long, and these can be made a constant length.
They show up from time to time at flea markets, and usually have colored collars around the shank, to help pick the right size (with the right chart to look them up. :-)
But in all likelyhood, since you don't mention your needed hole diameters, at least some of them are quite a bit bigger than 1/8".
Another point which I did not see mentioned is that each resharpening removes a length of drill flute proportional to the diameter, so with the varying lengths, each will usually accept about the same number of resharpenings before becoming too short (and too thick in the web) to work well.
I guess that you could make a series of drill bit holders for the common sizes which would put the tip of each at about the same distance from the chuck, to get an approximation of what you want.
Hey, why *buy* stub drills? I have a pretty good set in the 1/8 to 1/2 range. Usually from resharpening full length ones I've broken :-)
Also for holes in the 1/2" to 1" range, the OP could consider 1/2" shank drill sets. These in my experience vary much less in length than the big taper shank drills. Before I got my radial arm drill I used to use these to step-drill holes because it was faster to swap them over than it was to drive out a TS drill and seat the next one. Now of course I just drill a pilot hole the correct size, then the full size hole. Slow speed & power feed make life simple.