View Full Version : General Metalworking Enlarging a hole

Thomas R. Zack
06-10-2015, 10:00 PM
I need to enlarge a hole in 1/8" steel plate from 2" to 2 1/4".
I was thinking of putting a carbon bit for a die grinder in my router and try that.

what do you think of that idea?
I don't have a big enough compressor to use the die grinder!

Bruce Page
06-10-2015, 10:09 PM
You'll smoke that carbon bit in a heart beat. Lay out the 2 1/4 circle and use a jig saw. 1/8 steel plate will cut easily with a metal cutting blade.

Thomas R. Zack
06-10-2015, 11:20 PM
I meant to say carbide, but I'll give the jig saw a try first.

Dennis Ford
06-11-2015, 8:44 PM
A die grinder and router turn about the same speed; I think a carbide burr would work in a router. It might be bad for the router though, they make lots of fine metal shavings; if any of those shavings got inside the router motor - bad news.

Marion Smith
06-19-2015, 11:08 PM
I'd clamp it to the drill press table, centered under the chuck and raised up on a few blocks. Clamp/hold down securely with bolts and nuts. Then use a fly cutter to cut the larger diameter....but, that's the machinist me talking.

Larry Gipson
06-20-2015, 9:07 PM
I second the fly cutter. I'd first cut a 2" circle from plywood so that it will just fit the existing hole. That will locate the center. Then use the fly cutter again to cut the larger hole. I'd probably screw the 2" piece to a larger square piece to allow it to be clamped in place while I cut the second hole. Of course, if I had a lot of holes to enlarge and I wanted them perfect, I'd make a circle jig with the fly cutter, then use a Greenlee chassis punch to make a pretty hole. Surprised, but Greenlee is still in business. I have several of their punches I used to use when I built electronics with vacuum tubes.