Reaming out holes in thick steel?

[stuckmotor]

Maybe this is it. He did get the inner saw to stick out.

I don't remember him saying how he made it stick out, but, it sure stuck out.

 

[Smokeydog]

Sberry's picture in post # 31 shows one way that I have used. Clamp the right size hole over the too small hole:

View attachment 703870

I have used the hole guide plates with hole saws without a pilot drill many times to bore holes in truck, implements ant tractor frames. Great for re-centering a worn hole with a bigger fastener. Sometimes so obstructive used impact wrench with extensions and universal joint to drive the holesaw.
MK Morris bimetal hole saws come in 9/16” and 5/8” for smaller fasteners. Use oil and air to clear chips and cool on thick metal.

Plasma cutter with templates cuts accurate holes. Trying to drill a plasma cut hole is hard on bits. Big drills cost big money. Best use a die grinder with carbide.

If I can get it to stick, a mag drill is wonderful. Milwaukee with adjusting base, variable forward and reverse. Love to drill and tap threads with it. Mine has 3/4” drill chuck so haven’t tried the rotobroaches yet.

 

[Kschwennsen]

die grinder with a carbide burr, just make sure to use even pressure all the way around or you'll end up with an egg.

 

[Gord Baker]

I would advise renting a 1/2 or 3/4" Mag Drill, or invest in a Plasma cutter.

 

[rlipeles]

I want to enlarge four 13/16" holes in 1/2" thick steel to accept 7/8" pins. This on a piece of equipment so I have to use a hand drill. I happened to have a 15/16" black oxide bit, not too surprisingly that doesn't work at all. In 10 minutes I only penetrated about 1/8" in one hole. So I need to decide between buying an $80 construction reamer (high speed steel, manufacturer says it is OK for stainless) or pick up a 29/32" cobalt drill for under $50. I'm guessing the reamer would work better even though it is softer. Is that correct?

Can you switch to 13/16" pins?

 

[marhar]

I want to enlarge four 13/16" holes in 1/2" thick steel to accept 7/8" pins. This on a piece of equipment so I have to use a hand drill. I happened to have a 15/16" black oxide bit, not too surprisingly that doesn't work at all. In 10 minutes I only penetrated about 1/8" in one hole. So I need to decide between buying an $80 construction reamer (high speed steel, manufacturer says it is OK for stainless) or pick up a 29/32" cobalt drill for under $50. I'm guessing the reamer would work better even though it is softer. Is that correct?

Cobalt will do the job.

A common mistake people make is checking the progress of the drilling by pulling the bit out. Due to the heat created by the drilling one can actually harden the steel if they stop midway through.

Use cutting fluid while drilling to cool the metal and lubricate the drilling.

 

[mikedodd]

How about a big-a** rat-tail file? You only have to remove 1/32" all the way around. I'd buy the biggest, coarsest round file that will fit into the hole, and start filing.

 

[mikedodd]

If not a round file, how about an aluminum oxide tool for a Dremel motor tool? That ought to remove a lot of steel quickly.

 

[Barker806]

This will sound a bit odd but dull the drill a little. you can stone the cutting edge of the drill so it will not grab... Also if you can make some sort of drill bushing you can clamp to the outside of the of the part so you can hold it at 90 degrees. The trill pushing will also hold you on location.

If all else fails a bur and a reamer is a way to get it done...

I use a mag drill and dull the drill slightly so it will not grab and self feed. I hope some of this ramblings will help you!

 

[Jofang]

I want to enlarge four 13/16" holes in 1/2" thick steel to accept 7/8" pins. This on a piece of equipment so I have to use a hand drill. I happened to have a 15/16" black oxide bit, not too surprisingly that doesn't work at all. In 10 minutes I only penetrated about 1/8" in one hole. So I need to decide between buying an $80 construction reamer (high speed steel, manufacturer says it is OK for stainless) or pick up a 29/32" cobalt drill for under $50. I'm guessing the reamer would work better even though it is softer. Is that correct?

This is a difficult one unless you have a powerful drilling machine. Ideally, you should use a drill bit to remove so much metal in conjunction with a low speed, powerful, two handed drilling machine. An HSS reamer is intended for finishing, not for removing a fair bit of metal. You don't say how accessible the hole is for you to hold the drilling machine. My recommendation would be to use a drill bit held very firmly, braced if possible, as this is going to jam when you break through the other end unless you have plenty of torque and a very firm grip.