Drilling holes in metal?

[scruffy]

Bird, I have 3 of them still in the blister packs, some day, I too will find a use for them. Didn't buy them though, I found a tool box in the gutter with the bits and a complete tool set for drilling (cutting) holes in sheet metal, ie circuit breaker boxes....ain't used it either! I do have a 1" unibit (#21?) that I used years ago for drilling holes in auto floor boards for wiring installations.

 

[StoneHeartFarm]

RPM,

Quit blowin stuff up. /w3tcompact/icons/laugh.gif A Plasma Cutter is faster, easier, safer and almost as showy.

SHF

 

[DocHeb]

The UNI bits really shine when used in thin (<1/8") metal. They cut the hole without the binding and deforming that regular drill bits cause. You will end up with a burrless hole and flat metal on each side of the piece. I bought my first one at an electrical supply store - they sold it to drill though electrical panel boxes.

 

[PBMAX]

Yeap on the thin stuff they are nice.But I've used them on stuff up to 1/4" thick.Just keep in mind you may need to drill from both sides to achieve a nice clean hole on thicker materials...

Lil' Paul
Proud owner of TC21D
Laziness is the Father of invention.../w3tcompact/icons/laugh.gif

 

[Anonymous Poster]

For thin metal, unibit gets a 100!, 1/8" to 1/4" a hole saw, lthicker gets a twist drill.

A "silver and deming" type twist drill bit is larger than 1/2", but has a shank turned down to 1/2". They work best in a drill press, but a 1/2" drill motor will work OK. Keep your drill motor speed very slow, and use oil. I drill in steps of about 1/8, 3/8, 1/2, and then the silver and deming size. I have no problems with 1" dia. holes in 1 1/2" thick draw bar material.

The max RPM speed you should operate a lubricated HSS drill bit or hole saw in steel is 320 divided by the tool diameter, so 640 RPM for a 1/2" bit or 80 RPM for a 4" hole saw, etc.

Harbor freight sells a lot of very low cost tools. I got my S&D set 9/16 - 1" for about $20. I got what I paid for, but can drill holes and have not broken a bit yet.