Re: drill bits and techniques for drilling holes in metals

do you use a drill press or hand-held corded or cordless? drilling metal, it is vital that speed is controlled, the lower the better depending on the material. although Dormer is always a good brand to have locally, I have found that PowerCraft seems to up to performance and costs much less than the other. but still, too much pressure and hig speeds will always blunt even the best bits. Let the bit do the drilling....

Re: drill bits and techniques for drilling holes in metals

Try to use some coolant or cutting oil too.

Re: drill bits and techniques for drilling holes in metals

I use my trusty hand held corded B&D drill.

I think the speed and pressure is the culprit.

Maybe I can plug the drill in a 110v outlet and ease the pressure a bit (i"m a little bit heavy handed).

I'll try to look for a good set of drill bits.

Where can I buy the coolant or oil? Can I use those used in a vesicles?

Re: drill bits and techniques for drilling holes in metals

"plug it in 110v" - I wouldn't do that. Just use the speed control.

For coolant, you can also use kerosene. Overheating the bit will also soften it. If you hear the bit screeching, the bit is dull. I seldom use a coolant though aside from air. Just drill slowly and with a sharp bit.

For bits, I usually buy Dormer.

Re: drill bits and techniques for drilling holes in metals

"plug it in 110v" - I wouldn't do that. Just use the speed control.

For coolant, you can also use kerosene. Overheating the bit will also soften it. If you hear the bit screeching, the bit is dull. I seldom use a coolant though aside from air. Just drill slowly and with a sharp bit.

For bits, I usually buy Dormer.

There is no speed control in my hand held drill.
I wont be using the drill that much at 110v so I guess I can take the risk.

Re: drill bits and techniques for drilling holes in metals

OK, do tell us how it goes so others might benefit from experiment.

Since your drill does not have variable speed control, you might try gunning the drill meaning pressing the on button in short bursts. I don't really like this. I think it stresses the drill bit's cutting edge too much but in your case it is something you might try. Short bursts will prevent the build up of heat.

Re: drill bits and techniques for drilling holes in metals

a used oil will do ( cooking oil, pwede din ) ... dip drill bit once in a while sa oil ( every 5 - 8 seconds ) i've tried this and it works!

Re: drill bits and techniques for drilling holes in metals

Fourtheboys96 - what are you drilling - I notice you say 'stainless' sheet. Stainless is very hard for a normal drill - they are designed for softer stuff, mild steel and the like, There are not many more efficient ways to blunt a drill bit than to use it on S/S! You probably need a tungsten or similar bit for that (I don't know what sort, I learned not to try and drill S/S the hard way - don't do it now). Also, when you drill sheet are you sandwiching it between two pieces of wood? Gives a much cleaner cut.

Re: drill bits and techniques for drilling holes in metals

Hi,

On sheet metals I always use a smaller diameter drill bit than the final hole and use a step drill to clean it up. A step drill is a drill bit looking like a toy top. It gives a better finish that a regular drill bit. There are two types there is a smooth type and a stepped type. The stepped type helps with the hole diameter that you require.
HTH.
Cheers

Re: drill bits and techniques for drilling holes in metals

To have a longer life span for your drill bits, you must have different bits for some type of materials.
For example the stainless steel, ordinary bits will not last to make a number of holes (if your lucky), it will surely cry out and burn as you drill.
So for stainless steel and other hard metals with up to 1,000 N/mm2 tensile strenght and also like cast iron steel look for the High Speed Steel with Cobalt (HSS-Co) and also with DIN 338 standard on the packaging. It will do most of the job on tough material.
During drilling the harder the material, you must use the slower RPM. That way your drill bit will have a better grip with lesser friction thus minimizing the generation of heat that usually destroy the bit and the work piece.

Re: drill bits and techniques for drilling holes in metals

I found that using a 50-50 mixture of WD-40 and ATF ( automatic transmission fluid ) is a good substitute in the absence of real cutting oil.

I drilled these holes in 3/8" thick metal plates using cobalt bits and this mixture and got good results. Drill press on low RPM and consistent feed pressure. The largest bore was 1/2".

Re: drill bits and techniques for drilling holes in metals

I noticed MaxSell cobalt bits at a True Value. Label mentions stainless steel. Price range P56.75 (1.5 mm) to P446.75 (13.0 mm), average P165.21.

http://www.maxsellpowertools.com/Drill_Bits.htm

Re: drill bits and techniques for drilling holes in metals

Has anyone tried MaxSell bits? Isn't MaxSell a cheap MIC brand? As a rule I don't buy cheap MIC drill bits, and stick to brands like Dormer and Irwin. With a sharpening jig mention in another post of mine, the higher cost is not too big a burden. This is a rule for me now because in my experience cheap MIC bits are always a sad story.