Rotary sheet metal shear

[homebrewed]

I just bought a shear similar to this one, to facilitate making electronic enclosures. As such, the main thing is to get straight cuts without "pretzelizing" the pieces. I did look at the 3 in 1 machines but the inexpensive ones don't get good reviews and cost in the $250 range.

Since they are for electronics I'm not looking at making really large boxes. The main limitation is going to be my little Harbor Freight brake, which is 18 inches wide.

Does anyone have tips on getting the best results from this type of shear? Any "gotchas" to be aware of?

 

[Boswell]

wow I did not even know something like that existed. Obviously I can't help with any experience but thanks for the link

 

[C-Bag]

I think just like with all throatless shears you get “pretzelization” at the cost of being able to cut any shape. I have a throatless and a 3n1 and they both have their strengths and weaknesses. If you don’t want warpage and dead straight cuts the 3n1 rules. To do curved cuts and heavy stuff up to 16ga throatless rules. But it can be tricky to do straight cuts with it.

I know there are some bad QC 3n1’s out there but I think there’s just as many guys who don’t know how to set them up and don’t know how to use them. I’ve never seen a used one that wasn’t trashed. I was lucky to find my 3n1 NOS still on the shipping skid for half of new. For doing 20ga it works great for me and makes nice square cuts and does nice bends/boxes and can do rolls to boot.

If you want cheap and min warpage that can get into tight spaces a nibbler is the way to go IMHO.

 

[homebrewed]

wow I did not even know something like that existed. Obviously I can't help with any experience but thanks for the link

Believe it or not there actually is a powered version that attaches to a drill. Aside from a right angle drive attachment I've stayed away from gadgets that attach to a drill. Call me skeptical....or at least deeply suspicious...of things like that.

 

[homebrewed]

I think just like with all throatless shears you get “pretzelization” at the cost of being able to cut any shape. I have a throatless and a 3n1 and they both have their strengths and weaknesses. If you don’t want warpage and dead straight cuts the 3n1 rules. To do curved cuts and heavy stuff up to 16ga throatless rules. But it can be tricky to do straight cuts with it.

I know there are some bad QC 3n1’s out there but I think there’s just as many guys who don’t know how to set them up and don’t know how to use them. I’ve never seen a used one that wasn’t trashed. I was lucky to find my 3n1 NOS still on the shipping skid for half of new. For doing 20ga it works great for me and makes nice square cuts and does nice bends/boxes and can do rolls to boot.

If you want cheap and min warpage that can get into tight spaces a nibbler is the way to go IMHO.

A bit of warpage is OK since bending the sides of the box will act to straighten it out. I guess I will get to find out how it works for my needs.

Power nibblers don't necessarily cost a whole lot of money, either. Thanks for the information!

 

[C-Bag]

A bit of warpage is OK since bending the sides of the box will act to straighten it out. I guess I will get to find out how it works for my needs.

I think if you look close at the video of the shear you can see one side of the cut gets forced up and one side gets forced down. Thats the throatless part so you can cut compound curves so there’s a lot of hammer and dolly or arbor press to de schwangle so i can get a handle on accurate bends. Good luck.

 

[strantor]

Cut a half inch away from your line first. Then go back and cut on your line. The little half inch strip will do all the curling and your good piece that you want to keep, will stay straight.

 

[ChazzC]

Believe it or not there actually is a powered version that attaches to a drill. Aside from a right angle drive attachment I've stayed away from gadgets that attach to a drill. Call me skeptical....or at least deeply suspicious...of things like that.

You mean like this:


I got one if these last year; I doubt it would habdle the thicknesses noted, but worked well on 22ga galvanized steel. I haven’t gotten around to modifying the steel rod that connects to the drill handle on the hand drill a want to use it with. For $20 it was a reasonable buy.

 

[ChazzC]

Power nibblers don't necessarily cost a whole lot of money, either. Thanks for the information!

As noted in a previous thread, nibblers work well but produce a proliferation of sharp little crescent shaped shards.

 

[francist]

nibblers work well but produce a proliferation of sharp little crescent shaped shards.

No kidding! Used to use one to cut down aluminum window nailing flanges back in the day — those nibblings were straight from the devil himself, I’m sure.