[How do I?] How to make a large-ish through-hole in thick-ish CRS stock?

[jpg366]

What precision and finish? EDM?

 

[Winegrower]

I guess I am happy I don't have CNC equipment. This would be a pretty easy job on the Bridgeport with a boring bar, starting with a big center cutting end mill or 1/4" drill followed by a 1" SIlver and Deming drill. Bore out to taste using power downfeed and preset depth stop.

 

[AGCB97]

Sounds like a job for a annular cutter. Like a hole saw but more rigid, hole is fairly precise, finish is similar to endmill.

I agree but if you only need 1 hole and don't have the cutter then next best will have to do.
Aaron

 

[Cooter Brown]

You can run a Boring head manually on your CNC.......

 

[brino]

Depending on finish quality required (and being too cheap to buy a large annular cutter for one job) I would use a bimetal hole-saw cutting from each side. 1.5" thick means only 0.75 from each side, not too terrible.
Watch the speed, take it slow and clear chips often.

-brino

 

[RJSakowski]

I have cut a lot of holes in steel plate with a bimetal hole saw. One thing that I do is to predrill the pilot hole and replace the pilot drill with a dowel pin. It makes for less chatter. Use lubricant in the pilot hole as well as the cutting surface.

 

[f350ca]

I often drill a small hole at the edge of the hole saw cut. This allows the cuttings to escape.

Greg