K
Kludge
Guest
Somewhere there was a discussion about drilling small holes with carbide drills and the discovery that they break rather easily plus aren't really happy with some materials. Most of the comments offered suggested that carbide bits like to go real fast, which they do, but no alternatives to carbide.
First of, the tiny carbide drill bits are extremely brittle and will break if you look at them too hard. On the other hand, they can go through drill rod without a second thought. To do so requires equipment that has almost no runout - a watchmaker's drill press or lathe (both rated around .00005") or something along the lines of a Sherline (rated at something like .0005"), as examples - to minimize the flex and breakage. But not everyone has anything like that. In fact, from what I see here, the vast majority have "big boy toys" instead.
All is not lost. Waiting in the wings are two other flavors, HSS twist drills and spade drills. Neither one demands a lot of speed and both have enough flex that normal shop tools (lathes, mills, drill presses et al) can handle them. Chucks are available that go in a regular Jacobs or equivalent chuck that go down to 0" that can hold both types quite nicely.
The twist drills are available through any number of places, Micro-Mark being a decent source. Spade drills are a bit more tricky. I've already mentioned Dashto as a supplier of watchmaker's tools. Tom - a really nice guy, by the way - has a variable inventory since it's mostly from estate or bought out watchmaker's shops and some items go a bit more quickly than others. Periodically he'll have drill bits, many of which are spade drills and some are in sets that start at .004" and go up in .002" increments. A #80 drill is .0135" which is close enough to .014 that the difference shouldn't matter. These sets are designed to drill watch jewels so should be adequate for most tasks we come across.
I know I've seen number sized spade drill bits somewhere but I cannot remember where. If I can find them, I might swap out my HSS bits for them for normal use. They like to run slowly and don't load up with chips as badly as twist drills do.
One other type of drill bit sometimes used is a D-bit. These are used, among other places, for making bagpipes although they do have legitimate use as well. ;D An example can be found at http://www.bagpipeworld.co.uk/MakingBagpipes/Drill.htm which includes a reamer used for the same purpose. These are single flute drills and have been used in the past as gun drills and pretty much anywhere a deep straight hole is needed. The cool part is that it's not really necessary to need a deep straight hole to have need for one of these. They also like to run S-L-O-W and don't load up with chips quite as quickly as twist drills. The smallest I've seen on the open market is .05" or so but I wouldn't doubt that smaller ones are available.
Side note: Just for grins 'n giggles once (and to prove a point), I drilled a piece of .5mm brass rod along with a piece I could have silver soldered to it far more easily using a .004" (.1mm for all intents and purposes) spade bit. Then I used .1mm diameter pins (originally used to hold wristwatch hairsprings in place) to hold them together. After that, I sent the whole thing to someone who doubted I could do it. I never heard from him again - or got my piece back, for that matter.
As a second side note, I wasn't all that sure I could either until it was finished.
Best regards,
Kludge
First of, the tiny carbide drill bits are extremely brittle and will break if you look at them too hard. On the other hand, they can go through drill rod without a second thought. To do so requires equipment that has almost no runout - a watchmaker's drill press or lathe (both rated around .00005") or something along the lines of a Sherline (rated at something like .0005"), as examples - to minimize the flex and breakage. But not everyone has anything like that. In fact, from what I see here, the vast majority have "big boy toys" instead.
All is not lost. Waiting in the wings are two other flavors, HSS twist drills and spade drills. Neither one demands a lot of speed and both have enough flex that normal shop tools (lathes, mills, drill presses et al) can handle them. Chucks are available that go in a regular Jacobs or equivalent chuck that go down to 0" that can hold both types quite nicely.
The twist drills are available through any number of places, Micro-Mark being a decent source. Spade drills are a bit more tricky. I've already mentioned Dashto as a supplier of watchmaker's tools. Tom - a really nice guy, by the way - has a variable inventory since it's mostly from estate or bought out watchmaker's shops and some items go a bit more quickly than others. Periodically he'll have drill bits, many of which are spade drills and some are in sets that start at .004" and go up in .002" increments. A #80 drill is .0135" which is close enough to .014 that the difference shouldn't matter. These sets are designed to drill watch jewels so should be adequate for most tasks we come across.
I know I've seen number sized spade drill bits somewhere but I cannot remember where. If I can find them, I might swap out my HSS bits for them for normal use. They like to run slowly and don't load up with chips as badly as twist drills do.
One other type of drill bit sometimes used is a D-bit. These are used, among other places, for making bagpipes although they do have legitimate use as well. ;D An example can be found at http://www.bagpipeworld.co.uk/MakingBagpipes/Drill.htm which includes a reamer used for the same purpose. These are single flute drills and have been used in the past as gun drills and pretty much anywhere a deep straight hole is needed. The cool part is that it's not really necessary to need a deep straight hole to have need for one of these. They also like to run S-L-O-W and don't load up with chips quite as quickly as twist drills. The smallest I've seen on the open market is .05" or so but I wouldn't doubt that smaller ones are available.
Side note: Just for grins 'n giggles once (and to prove a point), I drilled a piece of .5mm brass rod along with a piece I could have silver soldered to it far more easily using a .004" (.1mm for all intents and purposes) spade bit. Then I used .1mm diameter pins (originally used to hold wristwatch hairsprings in place) to hold them together. After that, I sent the whole thing to someone who doubted I could do it. I never heard from him again - or got my piece back, for that matter.
As a second side note, I wasn't all that sure I could either until it was finished.
Best regards,
Kludge
