Drill Bits

[SoCal Dave]

What are the best 1/2" drill bits for 1/4" metal plates? I've got about 16 holes to drill and my drill bit doesn't do the job after one hole drilled.

[macbruce]

If it's made of high speed steel (HSS) most any brand will do fine. Are you using a hand drill? Are you drilling a pilot hole?Is it sharp?

[knots]

First maybe the drill bit is not the problem. Are you using a drill press or hand held drill ? If drilling with a hand held drill overheating and breakage are an enduring problem because it is difficult to maintain a constant pressure and angle. When I must use a hand held drill for larger holes I always step drill, that is drill the hole with several passes using increasingly larger drill bits.

If using a drill press almost any High Speed drill should drill 16 holes especially if you drill a small pilot hole. I keep my drill bits sharp with a Drill Doctor. It is cheaper and faster to sharpen than buy new, and drill past the point where excessive pressure is required for the bit to cut.

[bigfootnampa]

Use a cutting lube... most any oil will do. Keep the pressure on so that you get a steady curl. Bosch, Dewalt, Vermont American... most good brands of HSS are fine but the cheap no-names or discount table brands will rarely perform well.

[SoCal Dave]

Thanks guys. I'm using a drill press. I didn't us a pilot hole, but found a ridgid drill bit in the shop and that worked great. I did us oil and went slow and did all the holes with one bit. Thanks again.

[Frank Turley]

Ref sharpening, General Tools makes a nice "Multi-use Rule and Gage." I've had mine for quite a few years. Learning to sharpen free-hand will help when you're in the field and don't have a 'drill doctor' at your side. The drill point gage is simple, a 59 degree angle with scored lines for matching cutting lip lengths. In fact, such a gage was something that was formerly made by lads in high school metal classes. It could be M.S. sheet, but more often, was of sheet brass. The General gage is SS.

[SoCal Dave]

Thanks Frank for the tip. Hope the school is doing well in these tough times?

[ThomasPowers]

One aspect of drilling larger holes is getting the speed slow enough and the pressure heavy enough. Running to fast without enough pressure tends to draw temper on the drillbit *and* work harden the stock in front of the drillbit! Equipment designed to drill wood generally won't do a good job with metal. OTOH I have drilled 1/2" holes in 1/2" thick steel by hand---as in NO POWER using a hand cranked Cole drill.

[RGraff]

Speed and pressure, just as important as the bit. :)

[Mr Hensley]

I always step drill, that is drill the hole with several passes using increasingly larger drill bits..

I always step drill also. That's the way my dad taught me to do it, wether hand drilling or using a drill press. It takes a little longer spending the time to change bits, but its easier on the bits and equipment.

Max