Drilling big hole through steel plate

Jordan Baker · #1 12-02-06, 07:40

Hi everyone

Not ure how to go about this. I need to drill 2 holes through 1/4 inch steel plate. The holes have to be 1 3/4 inches.

I was thinking of using one of those large circular drill bits for making door knob holes. I wasn't sure if they make them for metal.

My grandfather suggested that I drill a bunch of smaller holes around the outside and then just use a hack saw to cut the rest.

Anyone have any other suggestions

Geoff Winnington-Ball (RIP) · #2 12-02-06, 08:25

Circular saws are not a problem with mild steel. Drill a pilot hole to start, and then use lots of oil as you go through the steel. You'll get a relatively clean hole - I've done it.

Tony Smith · #3 12-02-06, 08:59

Quote:

Originally posted by Jordan Baker
Hi everyone

Not sure how to go about this. I need to drill 2 holes through 1/4 inch steel plate. The holes have to be 1 3/4 inches.

Anyone have any other suggestions?

A 2 pdr AT gun will produce some neat holes, but they are only 40mm, or a little over 1 1/2in.

Not a Circular Saw , but a HOLE SAW is what you require. (Picture source, catalog p2246)

Richard Farrant · #4 12-02-06, 11:43

Quote:

Originally posted by Jordan Baker
Hi everyone

Not ure how to go about this. I need to drill 2 holes through 1/4 inch steel plate. The holes have to be 1 3/4 inches.

Anyone have any other suggestions

Jordan,

For 1/4" plate the hole cutters already mentioned are not really suitable as they are more suited to sheet metal or wood. You will probably go through several before finishing the job. A have recently come across what looks like a superb tool for doing this sort of job with infinitely variably hole size up to its limit, you just need a 1/2" pilot hole and a vertical drill press. According to the advert I first saw, it is available worldwide. Take a look at the following website;
www.farmideas.co.uk/custom.php?id=22

Another option is to drill a chain of holes and punch out the centre, then use an air powered die grinder with rotary files or burrs to finish hole to size, these are very fast cutters and can make a good job.

Richard

Geoff Winnington-Ball (RIP) · #5 12-02-06, 14:52

Quote:

Originally posted by Tony Smith
A 2 pdr AT gun will produce some neat holes, but they are only 40mm, or a little over 1 1/2in.

Not a Circular Saw , but a HOLE SAW is what you require. (Picture source, catalog p2246)

Picky-picky!

: Yes, a HOLE SAW (it was late when I typed that). They will work on mild steel, but only if used at slow speed and with plenty of CUTTING OIL. A drill press is ideal, but if the piece of steel is too large, a good variable-speed 1/2" hand drill with lots of torque will do it. Those cylindrical tapered bits will work as well, but wear out much more quickly.

Alex Blair (RIP) · #6 12-02-06, 16:04

Quote:

Originally posted by Jordan Baker
Anyone have any other suggestions

Jordan...
Get your self a Vari-bit...They work like a damn..
If you can use a drill press that is best..go slow and use Ridgid cutting oil..The dark stuff..
You can probably get both at a good plumbing wholesaler...Any of the trades guys can get them wholesale for you...
They are expensive but I have been using one ,the same one for 10 years at least..It will handle 1/4" plate with ease..
Like this..
http://www.lenoxsaw.com/varibit.htm

Alex Blair (RIP) · #7 12-02-06, 16:16

Jordan..
Belay that last post..Vari bits only go to 1 3/8"...
Hole saw ..carbide tip..go slow..same cutting oil..
Get them from the same place..
May have to go 2" and put a grommet in..1 3/4" is an odd size..

Phil Waterman · #8 12-02-06, 16:47

Hole saw, pilot hole, cutting oil, low speed, and drill press if possible. Drilling holes ½ and up is difficult with a hand drill if you can use a drill press or magnetic base drill unit. If you want a cheep alternative to a magnetic base drill for drilling holes on the truck you can adapt a small cheep ($65) bench drill press as a clamp base drill unit. You can see how I drill holes including hole saw 2 ½ holes in the frame which in places is two layers of ¼ so you are drilling through ½ inch. http://www.canadianmilitarypattern.com/Tools.html

chris vickery · #9 12-02-06, 16:48

Jordan, hole saws are OK. I used to sell stuff like that. The secret, if you can is to secure the workpiece if it is small enough to the drill press table. Go slow and easy as suggested, use plenty of oil and set the drill press speed real slow. They do make these for metal cutting, Starrett brand is amongst the best. You can buy them in 1-3/4". Another tool is a flycutter, which will do the job. If this is somewhere say on the side of your carrier, I think you may find that a holesaw will want to skip all over. They need constant equal pressure and a firmly mounted workpiece. Ialso like richards idea odf a series of holes, punched out and then cleaned up with a die grinder. Certainly a lot of work but doable. I guess theres many ways to get from point A to point B, just depends on your resources.

Jordan Baker · #10 12-02-06, 17:18

I guess i should have said that the piece is the rear plate for my UC. It is removable but it wont clear the drill press. I thought of doing the many small holes but it was going to take the longest. The holes were for the radio battery cables from the armoured box into the hull.

#11 13-02-06, 03:27

Jordan if the piece is removable why not just take it to a local machine shop and let them do it. It is surprising how reasonable they can be. In my younger days I often used them.

Snowtractor · #12 13-02-06, 04:58

Take it to a shop and they can plasma cut a clean hole in about 20 secs. Or as the old fellas suggest.
Sean

#13 17-02-06, 05:30

Just Go rent the Proper Rentle tool Jordan , as Brad said it's the fastest and easyest, I did it, Cost to rent tool was Cheap !! DO IT LAD!

Your Bud BIG MIKE