Specific kind of drill bit for steel plate?

[Magnus]

I find the drill bits I'm using to drill 18 ga. plate tend to dull somewhat quickly. I don't mind spending cash on good tools...what kind of a bit (1/8") should I look for? A particular brand or type...?

[LUCIUS ALFENUS AVITIANUS]

When you drill steel, simply put a drop of machine oil (or any oil) in the head of the bit. In this manner, the head do'nt get a high temperature and do'nt lost his hardness.

If you make the holes in plates for making a segmentata or so, why do'nt try to use a good heavy duty punch pliers? It woorks fine and it's very easy, quick and silent.

8)

[stevesarak]

It depends, if you’re using a drill press then a carbide bit will last longer, if you drill by hand, you take the chance of the bit grabbing the edge as it punches through. If this happens the tip bit can break or it can cut into the metal.

If you drill by hand then high speed steel should be good enough.

[Matt Lukes]

I use HSS (high-speed steel) bits generally. Friction heat doesn't affect the temper and hardness of these so easily and thus they are best for high-friction work like cutting metal. Definitely oil will help too. You should be sure the bit you choose is suitable for metal (usually marked on the packaging) and not just wood or plastic. You might be pressing a bit hard too- trying to get the bit to cut too quickly- and that will hasten dulling. Remember the bit is actually CARVING the steel. If you're pushing hard as you might if you were drilling wood, reduce the pressure some and try to make the hole a little more slowly.

[Magnus]

Cool, thanks guys!

I can't use a punch because I'm making holes in a solid, riveted cuirass...the punch wouldn't reach past the first set of wholes.

[Peroni]

I find it useful to drill a smaller 'pilot' hole first. Then enlarge to the required diameter. And, as matt says, keep the drill speed slow and let the drill do the work.

[Primvs Pavlvs]

You will never want to use a drill again if you get this........

http://www.harborfreight.com/cpi/ctaf/D ... mber=44060

[Magnus]

Yeah, my friend has a whitney punch. It'd be perfect if I could pre-punch the holes for the plates, but I found out the hard way I can't.

Here's the project:

http://www.geocities.com/thearmourroom/ ... hmycat.jpg

I'm just working on the back plates now. But because they're being bent in two directions...side to side and slightly top to bottom, it shifts the holes. And since the plates are rivetted right together, there's no way to get a whitney punch to any of the inner holes.

So I'm stuck hand drilling them...I'm going to try a combination of the oil and a good metal high speed bit.

[Matt Lukes]

You will never want to use a drill again if you get this........

http://www.harborfreight.com/cpi/ctaf/D ... mber=44060

I actually stopped using mine- the holes are a touch smaller than a commercial 1/8" rivet (at least the kind I could get), so I ended-up having to enlarge the holes a little with a drill anyway.

[Caius Fabius]

I picked up some titanium bits, use light machine oil and go slow.
Just don't use them on wood........

[Magnus]

Would a general purpose lubricant work as an oil?

[Matt Lukes]

I don't see why not- it's main purpose is to transfer heat. I don't use anything at all and have no dulling problems myself...

[richsc]

My first attempt at drilling was a nightmare, but it turned out that the chuck was worn and was wobbling the bit, so that it never actually bit into the metal. When I figured that out and bought a new drill, it was like butter. The 18volt handheld Black and Decker I have now has a quick release chuck, and I think it's beginning to wobble the bit.

Also, did you use a nail set/punch to put a depression in the metal for the bit to start in? That makes life a lot easier.

[Magnus]

Yeah, I pre-punch all my holes. I tried one of my other bits, it seems to be working well now.

[Matt Lukes]

Cool