Basic sheet metal work

[spike7638]

Every now and then I need to do something with sheet metal -- always stainless, because this is for a sailboat. I've got some stock in the basement -- some 0.075, 0.048, 0.06, 0.03 strip in various widths/lengths.

For today, I need to bend a 1" strip into an ell (one leg about 2", the other 1.5"), drill a couple of through-holes for #10 screws in the long leg, and drill a 5/8 hole in the short leg.

I can do the bending on a bender at work. I can drill the holes on a milling machine. I can clean up the holes with a countersink to de-burr the rough edges if I've got the terminology right.

My problem comes earlier: I want to use the thicker material -- 0.075 -- for which I have a 2 x 24 piece. And that material is too thick to cut on the shear at work. So what's the best way to get 1"-wide stock with a nice fairly clean edge?

On a related note, when I work with thinner material, I can cut it with the shear, which is great...but when I try to drill a large hole in it, I often find the drill "grabbing" right at the end of the cut and mangling the edge of the hole, or otherwise messing up the material. I'm sure I'm doing something wrong here, but I don't know what. Any thoughts? And clever solutions for making holes in thin stainless stock?

Thanks in advance.

 

[mzayd3]

Bandsaw to length, punch the holes


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[Submachine]

Bandsaw
For drilling, try some lubricant to see if that helps. Also, what is your drill speed?

 

[mmcmdl]

On a related note, when I work with thinner material, I can cut it with the shear, which is great...but when I try to drill a large hole in it, I often find the drill "grabbing" right at the end of the cut and mangling the edge of the hole, or otherwise messing up the material.

Drill a small hole and use the electricians punch out dies .

 

[cbellanca]

Cut the piece with thin cut off abrasive wheel on a hand grinder . It is not a good idea to use a band saw on such thin material unless the tooth count provides at east 2 teeth in contact with the material.
As far as drilling thin stock, bind it between two pieces of hard wood or some scrap aluminum. This will provide backing so the drill won't grab the thin material.

 

[Janderso]

“Two teeth touching the material”.
I had forgotten that rule. Thanks,

 

[BGHansen]

I do some work with stainless up to 0.050" and feel your pain. I have a Tennsmith 37" stomp shear and am really hesitant to cut anything over 0.036" in stainless on it. Instead, I use an 8" bench shear for cutting strips. Photo of one is below, run a touch over $100 and are rated (at least mine from Woodward Fab) at cutting 3/16" CRS plate. Mine cuts 0.050" stainless like butter. It does put a little curl in the stock, but it's easily worked out by hand. No burrs or rough edge to deal with after the fact either. I also have a project that uses 0.100" stainless and cut that on a band saw or with 1/8" wide horizontal milling cutters.

For holes, I'd recommend a Roper Whitney #5 Junior punch for the thinner stuff. They're rated for up to 16-gauge mild steel, work fine on stainless under 0.040". You'll need to drill the thicker stuff however and deburr.

Bruce



My sheet metal work bench. DiAcro 24" brake, 6" 4-ton notcher, 8" bench shear, Roper Whitney #218 punch press

 

[Winegrower]

For larger holes in sheet metal, I like the progressively stepped drill bits. Start with a small maybe 1/4” hole, and then switch to the stepped bit...wham, wham...you’re done.

For really big holes, i’ve used the 4 jaw in the lathe if the overall piece fits, or clamp to a plywood backing on the mill and use a boring head.

 

[tq60]

Step drill is a control cut device so best for sheet stock.

Punch sets also work well but limited by material type and thickness.

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[spike7638]

Wow...you go to sleep one night and the next morning magic has happened. Thanks, everyone, for these tips.

Winegrower I even have one of those step-drills, but somehow I've never used it on anything but aluminum, so it wasn't in my mind.
BGHansen: For shearing...I think that in the shop at work there's actually one of those bench shears tucked away in a corner, and I'd always sorta wondered what that thing might be. With your closer-up picture, it's obvious.
cbellanca: The 2-tooth rule is a great one... I'd never heard that, but I can think of a whole lot of mistakes I'd have avoided if I HAD! And using the cutoff tool is a great notion.

Thanks again, folks!