I’ve not found a source that’s 100%, but generally drills purchased from a machinist’s supply will be much better than those from the usual hobby shop. That’s true whether the drills are imported or domestic. True that domestic drills are usually better, but I’ve still had good luck with many imports. The biggest problem with machinist’s drills is usually not sharpness, but some are overly hard and break easily (much like carbide).
Machinist’s sources include: MSC, Wholesale Tool, Traverse Tool, Grizzly, Little Machine Shop, etc.
The use of Jeweler’s Pivot drills has also been suggested. These are often good, but are usually flat “spade” drills and not at all suitable for drilling deep holes. The meaning or “deep hole” is any hole more than six or so times the depth of its diameter. In the model RR uses for drilling grab-iron holes and such, about 98% of the holes need to be “deep” …usually “through” holes. The lack of helical flutes on pivot drills means they can’t lift the chips out of the hole, so have to be withdrawn to clear the hole frequently.
There are also “instrument” drills … be prepared to spend $$$ …. Like $50 per drill. Many of these are also spade drills. Search for “micro-drills”. One source used to be Louis Levin and Son, Inc, but apparently they no longer sell the drill bits … just the drill presses and lathes to use them.
Thus we’re back to paragraph one, using “Machinist’s Drills”. I buy them in packs of ten or a dozen, They’re cheaper, and even the imports are almost always much better than “hobby shop drills”.
P.S. These little drills CAN be resharpened. You need to use a strong magnifier, good light, and a fine sharpening stone. You also need to know what a properly sharpened drill LOOKS like. Such resharpening does not produce a truly correct tip shape, more like the tip of the spade bits, but is quite adequate for most hobby uses.
My most hateful modeling chore is locating and drilling for grabs and handrails, etc. I machine drill when i can with carbide drills, but practically, most have to be done by hand; and I am totally frustrated by the sheer plethora of dull #78-80 twist drills that seem to be endlessly supplied to us by almost all usual hobby vendors. This morning, after a failure to adequately be able to hand drill through some tough plastic (#79), I tossed the errant drill in favor of a new one, also from a popular hobby supplier. The new one could not cut butter either, and in the attempt to do so actually bent over (did..not..break!) at a right angle like bending a wire! Now, I do have a large supply of sharp (and brittle) carbide tip drills, but they are too risky to use with hand drilling- as you all already know.
So....where do you all find high quality reliably sharp tiny twist drills, most favorably from American, German, Swiss, or Japanese origins?