|Originally posted by aos
I don't know if a full size bench drill can accomodate tiny drillbits we use. I have a normal drill as well and I had to wrap drillbits in something to get them big enough for drill fasteners to hold on to. If you can find one that can accepts small ones, it'd be a good choice. Dremels are very expensive .
My bench drill uses an ordinary three jaw chuck with a 13mm capacity. It will hold a 1mm straight shank bit perfectly well, although you do have to be quite careful to make sure that it's lined up straight. That's easy to do - just run the drill slowly and watch for 'wobble'. You can also buy 'thick shank' bits, where the bit is 3-4mm diameter where it goes in the chuck and tapers to the appropriate diameter at the tip. These are less flexible than straight bits, so they break more easily, but they're easier to mount straight in a big chuck and I prefer them for 1mm and smaller sizes.
|Originally posted by Possum
SMorphet, how fast do your HSS Dremel bits wear out when working with steel? I've worn down one of my completely new bits only trying to enlarge one hole in a steel case to be large enough for a 1/4" headphones jack. How easily, or not easily, to the tungsten carbides work on steel cases?
I don't know. I prefer to use the bench drill whenever I can. The bits I use for steel (and aluminium) cases are just ordinary HSS. It seems to be worth spending a little extra for 'premium' quality ones, but I don't think there would be any advantage to using tungsten carbide. Tungsten carbide is great at withstanding wear from an abrasive workpiece, like fibreglass PCB boards, or masonry, but I don't think it's necessary for metals.
I've been using an 11mm bit for the jack sockets that I use. It's a Black & Decker 'Bullet' bit, which is designed for metal and doesn't need a pilot hole (just a punch mark). The trick is to go slow - about 450 rpm for this diameter in steel, and feed slowly - don't try to force the bit through the workpiece. I've done about 300 holes with this one bit, building patchbays, 1mm steel on the backs, 3mm aluminium on the front, and it's only just beginning to feel a bit old. It can help to use a cutting lubricant, messy, but it cools the bit and prolongs its life. It's particularly helpful for aluminium which is soft and doesn't have much lubrication of its own, and so tends to squeal.
If you're enlarging an existing hole then a drill may not even be the right tool. Enlarging from, say, 10mm to 12mm with a drill would be really difficult unless you have the appropriate vices and jigs to keep everything aligned. I'd prefer to use a file, or a hand-held reamer.
I'm sure you can't fit bits of this sort of size into a Dremel, so I wonder what you're trying to do? Are you drilling lots of little holes around the circumference? If so, then you're making life very difficult for yourself, but I wouldn't expect a good quality bit to wear out particularly fast. For, say, 2mm holes in steel, use about 1800 rpm, and make sure you drill straight down. If the bit starts sliding into adjacent holes, or if you push it sideways and try to use it as a router, then you'll break or wear the bits very quickly.
Of course, at jack socket sizes and above you should also be considering punches. You can get clean holes in really large sizes, and you can even do non-round holes - great for BNC connectors, etc. The disadvantage of punches is that you still have to drill a smaller hole, and screw all the fiddly bits together, so it can be quite slow.