On May 8, 6:47 pm, Gene Kearns
wrote:
On Tue, 8 May 2007 18:05:43 -0400, JimH penned the following well
considered thoughts to the readers of rec.boats:

I need to drill some new bolt holes in 1" and 3/4" diameter SS tubing to add
a step to my swim platform ladder.

Will I need a special drill bit for this or will my ordinary metal cutting
drill bit work?

Thanks!

My personal choice would be to drill a pilot hole through both sides
of the tubing (from one side) about 1/16 of an inch or so in diameter.

I would, then, use a unibit to size the holes.http://www.crawfordtool.com/unibit.html

The pilot hole will insure that the holes enlarged by the unibit line
up. The unibit has a straight flute and will not grab in the tubing.

Depending on the size of the screws, you probably can get away with
just drilling through with a conventional bit, but bear in mind, when
the tip breaks through it is going to try to screw it's way through
the tubing and grab.

Unibits can be bought pretty cheap at places like Northern Tool or
Harbor Freight.

Stainless steel = slow speed and positive feed, don't let the drill
rub without cutting.

--

Grady-White Gulfstream, out of Oak Island, NC.

Homepagehttp://pamandgene.idleplay.net/

Rec.boats at Lee Yeaton's Bayguidehttp://www.thebayguide.com/rec.boats

I know you did not ping me, but I would also go with a pilot hole, and
slow, positive feed, etc. First however I would probably make a quick
jig (from a chunk of maple I keep around for just such an
occasion and use a drill press. I would put a pilot in one side,
then line the piece and jig up in the clamps. This allows for a very
quick way to get the 2 pilot holes lined up correctly. Then I would
work my way up to the correct size with good bits.