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Cutting Hole through 3/16'' 306 Stainless

KGM

Plastic
Joined
Feb 13, 2020
Good Day

I am in the process of building an instrument air test bench. I'm looking to find a hole saw or punch set that is capable of creating a 2 1/2" hole in a 3/16" thick (and what I beleive is) 306 Stainless bench.

I have tried a greenlee ultra cutter, that is allegedly for cutting steel, but the teeth have already worn out.

Any tips for getting through this stuff?

Thanks

Kevin
 
I don't think any Greenlee panel punch is going to do the job. They are made for pulling holes in relatively thin mild steel. It sounds like you may be lacking in the tool department so if it were me I would drill a series of holes and connect the dots. File it smooth when you are done or use a carbide bur to clean it up.
 
Most likely 304 S/S. 306, AFIK, is not a thing. The cutter was probably up to the job but the speed was way too fast. Calculating (CSx4)/D, (40x4)/2.5= 64 rpm. I'm assuming you were using a hand held power drill? Even a Bridgeport won't go that slow. Punching that hole would take more tonnage than you can muster with a wrench/knockout punch (I've forgotten the calcs on tonnage). Even the hydraulic power-pack punches are limited to about 10 ga. in mild steel, less in stainless. A mag drill with rota-broach might be an option except 300 series stainless is not magnetic.

I'm thinking you might have to plasma an oversize hole and make a lighter gauge bezel ring to fit, then bolt or weld it to the table.

If this stuff was easy, anyone could do it.
 
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...I have tried a greenlee ultra cutter, that is allegedly for cutting steel, but the teeth have already worn out.

Any tips for getting through this stuff?
Looking at that Greenlee hole saw, it doesn't really look up to the task. They describe it as made for cutting conduit.

You've already burned up one hole saw, there's a good chance you've work hardened the material. (It's probably 304 or 316, no such animal as 306.)

Get a couple Lenox bimetal hole saws, flip the piece over and work from the other side. Go SLOW, lean on it, and use lots of cutting oil. It will dull, so when it stops cutting, switch to a sharp one.
 
Good Day

I am in the process of building an instrument air test bench. I'm looking to find a hole saw or punch set that is capable of creating a 2 1/2" hole in a 3/16" thick (and what I beleive is) 306 Stainless bench.

I have tried a greenlee ultra cutter, that is allegedly for cutting steel, but the teeth have already worn out.

Any tips for getting through this stuff?

Thanks

Kevin


Id be looking into getting it cut out from a plasma or water jet or laser. When you get to that size, hole saws just aren't economical.
 
Kevin,

Welcome to the forum. That material work hardens pretty easily and using a hole saw too fast will be the kiss of death. Annular cutters that large are very expensive and you would need the proper drill or machine to utilize one. I don't think a Greelee punch would make it through 3/16" stainless.

I would try another, new hole saw using the same pilot hole, but from the other side of the material if possible. Run it slow, keep it cooled and see what happens. You may have to switch to a new hole saw part way through the chore but the trick is to go slow, keep the saw cutting, don't let it skid without making chips or the material will harden and kill the saw again. Slow and good pressure on the drill to keep it cutting.

Stuart
 
Good Day

I am in the process of building an instrument air test bench. I'm looking to find a hole saw or punch set that is capable of creating a 2 1/2" hole in a 3/16" thick (and what I beleive is) 306 Stainless bench.

I have tried a greenlee ultra cutter, that is allegedly for cutting steel, but the teeth have already worn out.

Any tips for getting through this stuff?

Thanks

Kevin

Unlikely you even have acess to anything SLOW enough and with the "push" to make a hole-saw or annular-cutter do the do. Believe it or else, HAND rotating a cutter with a tommy-bar or ratchet and a draw-up bolt instead of a pilot could get through that sheet more rapidly than too-fast-burn-it-up POWER. See Old Skewl pipe threading, et al. Tedious, but it let even High CARBON Steel dies last for years.

As a table or bench top can be a tad unweildy and waterjet and laser are not necessarily "portable"?

:)

Cheap and cheerful is a skilled hand with a plasma cutting rig that usually IS "portable"..

Your failed hole-cutter attempt is the line to follow. Clean-up the sharp edges and burrs with air or electric die grinder.

Insert nice-looking bezel ring.

Go do something more difficult.
 
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Last month I needed to cut a 1.25" hole through some 1/8" mystery grade stainless sheet for a car project. I used a cheap Dewalt hole saw. Kept the rpms down, kept it cutting, and a few squirts of cutting oil. I also sandwiched it between two pieces of 3/4" oak to help guide the saw at the beginning of the cut.
80497007_10218236849527499_7722553882009665536_o.jpg
 
Last month I needed to cut a 1.25" hole through some 1/8" mystery grade stainless sheet for a car project. I used a cheap Dewalt hole saw. Kept the rpms down, kept it cutting, and a few squirts of cutting oil. I also sandwiched it between two pieces of 3/4" oak to help guide the saw at the beginning of the cut.
View attachment 278660

3/4 pine - or plywood scrap - wudda done easily as well, 3/8" ply, even.

Seasoned White Oak - commercial high-grade stair treads right useful all-around - can ruin a hole saw easily as fast as Stainless, if not faster.

Oak just ain't all that happy with cutting fluid nor oils, yah expect to USE it for sumthin' cosmetically decent.

Shop air can help. Cold weather, yah can even get free shop heat, yah ain't keerful? Mind the smoke, though...

:D
 
I hate fly cutters, but I think that might be a good option for you, IF you have a drill press. Go slow, don't force it. Cut part way through, then flip it over and cut from the other side. Do NOT attempt this if you are using a hand held drill!
 
I hate fly cutters, but I think that might be a good option for you, IF you have a drill press. Go slow, don't force it. Cut part way through, then flip it over and cut from the other side. Do NOT attempt this if you are using a hand held drill!

More better you should KEEP ON "hating" fly-cutters than to attempt to use one on grabby SS without a seriously stiff and stout rig back of it!

Better-off to nibble the b**tch with an oscillating saw, brazed carbide grit blade. BTDTGTTS.. rectangular cutout for an ignorant electrical outlet, to be precise as to a safer, if slower Pain In The Ass.
 
BILL,

Your nutso syco-bable is going to drive the OP over the edge for Gods sake! It's obvious you haven't been there..or even remotely done that, or you wouldn't be saying the shit you're saying. Give this guy a break and let him succeed (or fail) on his own.

Stuart
 
I hate fly cutters, but I think that might be a good option for you, IF you have a drill press. Go slow, don't force it. Cut part way through, then flip it over and cut from the other side. Do NOT attempt this if you are using a hand held drill!

Given the OP's lack of experience and equipment, I'd think a single-edge flycutter would be a poor choice for cutting this hole. Even a good drill press doesn't have the spindle/column stiffness needed to maintain uniform edge-to-part relationship, and without a center spigot maintaining centration it wouldn't take much to have an offset-induced grab and break.

From everything I've read so far, I'd go with drill a periphery of smaller holes and file/grind the hole round. Lowest entry bar, relatively safe (with good eye protection), and doable with basic tools and skill.
 
My vote is to chain drill it and clean it up with a die grinder and file.
I cut a rectangle hole in a 11 gauge panel using this method worked good.
 
2 1/2” is just not that big a hole, shouldn’t be a problem with a Couple of 10$ BI metal hole saws like a Lenox. Yep, go slow, use lube! A decent cordless on low, and use maybe 1/2 of that low speed at the most. Starting from the backside is good advice.

The cleanup after “chain” drilling would really be a pain.

Fly cutter, no, don’t do it! In 3/16 S/S I wouldn’t do it on the BP mill even.
I’d still use the holesaw. Gullets get jammed up with swarf so you need to peck a lot, but you can’t beat the price. (Yes, it’s not a tight tolerance tool, I know!)

That is too big for the “smaller” more common magnetic drills, and as mentioned the annular cutter is like 100$ or more, (non-magnetic surface isn’t a problem tho, just clamp a steel plate to it).
 
Many years ago I worked in a machine shop filled with European machinists. It was actually a company based in Hamburg Germany. Most,if not all,the machinists used a mixture of 12/1 water/epsom salt for drilling stainless. This was over fifty years ago and I still use it today. For those dyed in the wool skeptics out there...try it and see for yourself.
 








 
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