Sheet metal/Aluminum drill bit help

[Exterous]

I need to drill some holes through some sheet metal and aluminum. Form past experience I know that my drill bits suck for any type of metal work. What would be a good idea to buy? Cobalt? Titanium coated?

One particular need to to be able to drill a hole through a thin (guessing 1/32") piece of alumium above my head. Its a long thin piece with no backing to it so it bends out of the way if I press to hard on it. (I am trying to avoid cutting holes in the drywall if I can) I just need two screw holes in that one

Any recommendations?

 

[shortylickens]

I just asked this question a while back.

Good stuff is tungston carbide, but those are super expensive.
Titanium coated is cheaper and will do the job well enough, provided you have the horse power.

 

[edro]

Literally any standard drill bit will work for what you need.
Just don't press hard so you don't deform the metal or cause sharp edges on the exit side.
Use high speed and push slowly. Use a tiny bit of WD40 as lubricant and the bits will last much much longer.
(WD40 is a decent drill bit lube for DIYers.)

 

[Exterous]

Literally any standard drill bit will work for what you need

:hmm: The ones I have didn't work for the aluminum in the ceiling but that might just be that they are dull or that I am generally shit out of luck and am going to have to cut a hole in the drywall

 

[Sluggo]

For drilling thin metal, these step drill bits work great. You might need a tiny regular bit to start a hole or make a dimple, the the step drill makes short and easy work of it.


http://www.amazon.com/Milwaukee-48-8...909103&sr=8-11

 

[stargazr]

Regular drill bits are ok (HSS is an excellent quality drill). Be careful with aluminum, it can grab real easy. Take your time and feed the drill at a steady rate as possible, like a drill press. Clamp your work whenever possible.

Use kerosene, it's almost as good as very expensive chemical alternatives. It keeps the aluminum from gumming up on the cutting edge of the tool.

 

[911paramedic]

Regular drill bits are ok (HSS is an excellent quality drill). Be careful with aluminum, it can grab real easy. Take your time and feed the drill at a steady rate as possible, like a drill press. Clamp your work whenever possible.

Use kerosene, it's almost as good as very expensive chemical alternatives. It keeps the aluminum from gumming up on the cutting edge of the tool.

Another good tip is clamp a piece of wood behind it if you can.

 

[stargazr]

Another good tip is clamp a piece of wood behind it if you can.

:thumbsup: especially thin material

 

[Squisher]

Chances are the bits you have are just dull. New bits come with very shallow relief angle on the heel which really makes the bit rub as soon as it gets a little dull.

You can also drill first with a small drill the size of the chisel edge of the larger drill.

 

[Lemon law]

The big problem with drilling sheet metal and soft materials like Aluminum and brass is the rake angles of typical cutting tools. Especially if the cutting tool if fed by hand pressure.

In industrial plants engaged in mass production, specifically designed tools with zero or even negative rake are used to prevent drills and such from grabbing as the tool bit breaks through. But as someone who used to be a tool maker, its very easy to make such zero rake tools if you have access to a cutter grinder.

But if you have good hand eye co-ordination and safety goggles, you can dub off the rake off an ordinary twist drill with either a bench grinder or a dremmel. The only trick is to do both faces evenly. Failing that the drill will drill oversize and non straight hole.

The other thing to understand about drilling small holes through any materials is that most drills simply move at too slow an rpm to do any good. For example, an ordinary HSS steel cutting tool will have its cutting edges soften if you spin it faster than about 500 rpm in steel, a 1/32" drill would require 4000 rpm to cut and feed best in steel. And a full 12,000 rpm to cut and feed best in brass or aluminum. And even off the shelf 1/4 inch drills seldom spin faster than 1500-2000 rpm. And why something like a variable speed dremmel that can spin up to 20,000 rpm is better for small hole drilling.

 

[Exterous]

Thanks guys!

 

[Howard]

Thin sheet metal should either be punched, lasered/WJ, or step-drilled.