What sort of drill bit to get through stainless stell

[jlanng]

I'm trying to mount an antenna on the A-Frame. I need to drill a 26mm hole through about 3mm (at a guess) of stainless steel. What sort of drill bit should I buy? I have ruined a couple of bits trying already!

Thanks chaps

[Richard B]

Ordinary HSS drill bit. Use slow speed otherwise you'll blunten it straightaway. About 5 rpm is fast enough.

[Richard B]

Hey, 26mm is a big hole! Drill a pilot hole first, then work up to the larger size.

[jlanng]

OK thanks.. will just have to persevere with it.

Oh, it's 16mm!

Thanks for the hasty reply

[jwalker]

Buy a stepped drill, lotsa different sizes on the one drill, or a cone cut which is a tapered drill and excellent for sheet material. As Richard says, run it slowly and keep it well lubricated, as in flooded with lubricant.


You still sleeping nights Richard?

[AndrewH]

If you do follow the "go up through the sizes" option rather than JW's cone cutter, then I would recommend looking at some of the titanium coated drills (Bosch do a reasonable range). They tend to last a good bit longer than standard HSS and I've found they leave a much cleaner hole with less burrs to remove

Andrew

[Brian]

5 RPM Richard??
Thats one turn every 12 seconds? Sounds a bit slow to me?

[Richard B]

You're right!

I was thinking 5 turns per second... 300rpm!

What's sleep?

[jwalker]

Originally Posted by Richard B

You're right!

I was thinking 5 turns per second... 300rpm!

You were closer first time. At 16mm dia 60ish would be nearer the mark.

What's sleep?

[Erin]

If it's flat and you can get to the other side, you could do what I did and get a hole cutter from Maplin. You drill a small hole through the metal, fit the hole cutter either side and then tighten up with an allen key, and it slowly cuts out the disc of metal.