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Cutting non-ferrous metals with jump shear


#1

Hi All,

We have a nifty older but newly sharpened jump shear at my new mega
studio. I have a question that I know many of you will have the
answer.

Our shear says it can cut up to 12 ga mild steel.

For non-ferrous metals, silver, brass, copper, what is the maximum
width and gauge that it should cut. Our is bending the metal, which
says to me that the blades are out of alignment. If this is not the
case, can you help diagnose it?

Also, these blades seem to cut more like scissors and less like a
jump shear guillotine style. I’m assuming it should be more like a
guillotine, correct?

BTW, the new studio is awesome. My next door neighbor just build a
complete CNC machine out of MDF, bolts, chain drive, hooked it up to
a computer with cad and made a custom vacuum system for the dust. He
is 22. Cool.

Karen
www.cleverwerx.com


#2

If it is set up for 12 ga steel then the gap between the blades may
be too wide. Shears ideally need to have a gap appropriate to the
metal thickness and type they are cutting. Often on a jump shear this
is set for some average thickness to allow for a variety of metal
thickness and type. But 12 ga is pretty thick for a jump shear and to
keep it from binding up the gap is probably too wide for non ferrous
metals. And all jump shears I have seen an angled upper blades to
reduce the force needed to cut the metal. With a capacity of 12 ga
steel I would be surprised to not see a greater angle than more
typical jump shears. If you have someone who has experience adjusting
these type of shears it should not be too big a deal to adjust the
gap. If you don’t know what you are doing however you can ruin the
cutting edges in one pass of the blades.

Jim

James Binnion
James Binnion Metal Arts


#3

Karen,

It does sound like the shear’s blade is misaligned. Generally, people
don’t use a lot of thin ‘jewelry’ metal with them, so the tolerance
between the cutting edges is set with a little slop. Two piece die
sets are also engineered with slop (which would never do in my world
of tight-fitting pancake dies (yes, the entire universe does in fact
revolve around pancake dies (^;)). The big warehouses I send people
to for copper sheet are notorious for loose shears and edges with
nasty burrs.

I would get that alignment tuned in and see how it behaves. The
thinner you want to cut, the tighter and more even it will need to
be. Some brass and nickel siver is very uncooperative in the thinner
gages unless the shear is tip-top. It’s surely ok to exceed it’s
stated capacity with metals softer than mild steel, but if you ever
need to cut some 10ga 14k , that could be a problem.

Another issue might be the hold-down device. Is there a spring-loaded
bar going across in front of the blade, that presses down on the
stock when you stomp?. Those are nice but get in the way when working
with small pieces.

If there isn’t one, or it’s not working, that would contribute to
metal bending.

I don’t quite get what you mean about scissors vs. guillotine, so
I’m leaving that alone.

Good luck with it (and the rest).
Dar
sheltech.net (work)