Drill Bit(s) for Stainless Sheet

Old 12-03-05, 02:15 PM
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Drill Bit(s) for Stainless Sheet


Thanks for this forum

We're installing Stainless gutters on the roof on the 2nd floor. We use Rivets to join these sheets.
I noticed the HSS bits dull immediately, the bits are about 3mm in diameter. The stainless sheet is maybe about 1mm thick.
To add difficulty some of the gutters is already installed on the roof.

I'm just looking for 1 piece not a whole set of Drill bits.

What type is available in a local store? I noticed a "Cobalt" & Titanium, coated?
Any techniques to recommend to do the job?

Help is very much appreciated.

Thanks for all the help
Old 12-03-05, 02:54 PM
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j813, Welcome to the DIY Forums.
I am not an expert in this field but I have done my share of drilling. Part of the problem may be your drill speed. Stainless heats up rapidly. I always use a slower speed for it. I also use water as a coolant rather than the "tap easy" type coolants. When threading stainless pipe, we always use water as the coolant rather than oil. Some of the coatings on drill bits are only to up the price. They do nothing for making the drill bit work easier or longer. Watch this post for the expert opinions and answers. Good luck.
Old 12-03-05, 05:11 PM
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20 years ago I installed a 3/16" sheet of stainless. Cobalt bits were the only ones I had any luck with.
Old 12-03-05, 07:59 PM
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Cobalt Drills are the choice for stainless.
The cobalt drills have a thicker web so you can feed them harder then HSS drills and a different angle and split point.
What they sell at some stores maybe something else.

Carbide drills would work but not for someone without experience. they will chip/shatter without much effort.

Stainless will work-harden around 800 degrees F. That's why you must keep the RPM down less rubbing, more cutting.
You need to keep a chip going at all times, If your not cutting your Hardening the material.

Center punching will help.

For a 3mm drill on stainless, keep the RPM lower then 800 RPM
for hand drilling maybe 500 RPM.

Wear safety glasses most if not all drills can shatter.
Old 12-04-05, 03:51 AM
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Gwiz is Gright!
Old 12-04-05, 04:39 AM
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OK, that's help.

Now I guess the only way to reduce speed of an ordinary Hand Drill is to push the power button on & off?

BTW anybody have a link guide of how to handle drilling to various types of metal?

Anyways the advice I got already is good, thanks again.

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