dewalt metal shear dw891 - dull blades?

I bought this shear about 6 months ago and have been cutting 5052
sheet aluminum with it on an irregular basis. The aluminum has been
thin, most of it 20ga. and one small piece that was 16ga. It cuts
like butter, leaves no marks on the finished surface, and leaves
smooth edges. It's my favorite new tool, and my plasma has been
taking a long vacation.
I'm now using it to cut several pieces of 20ga. stainless 304 #4
finish for a kitchen. I made two cuts yesterday that were 8' long
without too much problem, but now it's not doing anything. It's
totally sucking. It's supposed to be able to cut up to 16ga.
stainless. It's stalling at a low cutting speed, and the shear won't
even move if I give it pressure. If I gun it to it's max speed and
give it pressure, it moves, but not well, and it marks the crap out of
the metal. I can't use this to cut the finished piece, obviously, if
it's going to mark it all up, and if I have to give it that kind of
pressure to move (which I shouldn't), it's never going to be a
straight cut. I don't want to use plasma because of the heat-affected
areas (the edges will all be visible). I've tried cleaning the blades
and adjusting them, which only affects the curl of the cut-strip. It
still cuts scrap aluminum with no problem, but it's still not cutting
the stainless. Do I need new blades? Anyone have experience cutting
finish work with shears v. plasma, or with these shears? I'm not
aware at all of the sharpening/replacing timeframe for these blades.
I wouldn't be surprised, of course, that the stainless would shorten
the life of these blades significantly (giving to the compared
hardness of stainless), but I'm surprised that they would need it
already. The blades do show a little bit of wear. Is there something
to do to minimize blade wear?
Note: the center blade of this shear wiggles laterally just a tad
(1/64" or less) - I'm assuming that's normal.
Thanks in advance for any advice!
Reply to
Brook Halvorson
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Cutting stainless with these handheld shears is a waste of time. The metal is too ductile and strong. Dull blades is the best that can happen. I've seen broken blades and sprung anvils. I have done 19 gage but 16 is too much. Even on a $20,000 hydraulic shear we have to reset the clearance when switching back and forth between 16 gage stainless and 20 gage aluminum. Stainless steel has twice the ultimate strength of mild steal and the higher ductility means that it stretches a lot more before it breaks. Exactly the opposite chacteristic than what you want for shearing.
You can acid etch the stainless to remove the heat marks from the plazma torch. This is an excellent way to cut stainless that I've used before. You can also polish off the heat marks. That is what we usually do.
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