From time to time our plasma table makes holes that are less than desirable. (Perhaps there’s a different discussion about how to get the best cut on a plasma table but we’ll save that for later.) We just clean these up freehand with a die grinder and carbide burr, but that doesn’t have much control over hole shape or diameter.
How about mounting a straight sided carbide burr in a woodworking router, put a template follower bearing on top, drill a template, clamp template to the work, and grind away? This would likely only get done when precision is needed but there would be times were I’d prefer this done!
In my experience carbide endmills have a hard time with flame cut edges, so odds of a strait shank templating bit working is very slim. Maybe if you can find a specialty bit to make it work.
Unless you are highly skilled, using a burr to correct a hole problem is like making dominoes with an axe…It can be done, but you’ll waste a lot of material before you get good at it. Burrs don’t like being run against a rough edge while being held as rigid as you would need. If the holes need precision, then I’d switch to a different method of making them. Rotobroaching, drill/ream, or punching would be much better.
What I’m talking about is a carbide burr for a die grinder. They’re also called rotary files I believe. I’m not talking about an actual endmill or router bit. We use these carbide burrs to clean up rough plasma cut holes, and they are easy to control, working slowly with light pressure. The idea was to use a woodworking handheld router, since they spin at a similar speed to a die grinder, hold the tool perpendicular to the work, and can be used with a template. Then its just a matter of slowly working in on the high spots towards the line.
If it needs to be drilled or machined, we do that. But sometimes a hole or holes comes out poorly on the plasma and getting a good clean finish is appreciated in some applications.
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I also would like info on this. What ever you come up with please share.
Here’s an interesting one, may be useful
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I had occasion to try out the router with carbide burr and a template. While the accuracy still isn’t what you’d get with a drilled hole its way better than freehanding with a die grinder. I’d rather have just drilled these with the right bit, but the guys had already burned these big plates and the bit is 1-9/16" so an odd and expensive size.
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