The idea of hammering (ball pein) a piece of tool steel (0-1 flat
stock, 1/8" thick by about 1.5" ) is what I am going to do to create
a master plate. I made a small test plate and heat treated it after
peining and flattening it. Being hardened, it’s permanent and can be
used to roll production plates that will have bumps and deliver
depressions into the end-use material, duplicating the original
peining as faitfully as is necessary. The great advantage of hardened
steel is that it won’t curl, because the raw tool steel will curl in
the mill. It’s soft enough to hammer cold, and soft enough to curl,
and would wear out immediately if you were to roll another piece of
raw tool steel against it.
So, the master plate can be used to roll production plates also in
tool steel, and I did this with the test plate and a piece of 1/32"
flat stock. Some issues arose around how thick to make the production
plate, because it will curl and warp less, the thicker it is, but I
think 1/16" combined with a 1/8" master is all my particular mill
will handle, thickness-wise. Or perhaps 3/32" for both plates.
Regardless, the production plate will also be flattened and hardened
(quenched in oil and tempered to about 450-500 deg.F.( hard but not
too brittle, a smidge harder than a hammer )). It will not curl when
running silver strips in the mill with it. I had done a very similar
process a couple years ago, only with textured brass sheets as the
production(and sometimes master) plates, and these had short (but
moderately useful) lifetimes because of the curling. This process
took multiple runs through to get decent coverage, but with my test
plates, once through was perfect, because the pattern was not worn
(nor will it be ) and the plate is perfectly uniform in thickness.
One tricky part of rolling the production plate off of the master
plate is that the mill has to be set just right to give a deep
forming, but not so tight that the mill bogs down. I have a Pepe
188.00 (4" by 2" rollers) that I took the handle off of and put a 1/4
hp gearmotor onto, driven by motorcycle chain and sprockets. It’s
gotten stuck a couple times… not a good thing for equipment or
user… not particularly dangerous, I don’t think, but it gets the
adrenaline going!!. If it’s set too loose, the forming isn’t deep
enough and unless you can realign the plates perfectly (I can’t) for
another run, you have to start over with another plate.
Also out of all this came an idea when I was replying to a reply from
Durston Rolling Mills. I was inquiring about a custom made roller for
this job, but although they can do it, it’s cost-prohibitive for the
customer I’m doing this for. But that made me think of taking a raw,
unhardened roller from a mill company, or having a duplicate
fabricated, and hammering it. I don’t know how practical or costly
that would be, since I don’t know if there are gears machined onto
the rolers or not. If not, it’s probably a cost-effective idea for
some folks. Anyway, you’d pein and harden the roller and then running
production plates off of it would be simple. Or, because the bumpy
texture on metal rolled with a first generation peined plate also
looks very nice, one could simply use the peined roller to …um,
roll
very nice looking bumpy metal in a one generation process. Smiles.
I am planning on taking some pictures and making them available
online after I get this job going. Oh, the job itself is to make bead
halves in hammer-textured silver, which the client will make into
full beads. I have to make some one-step, no-tab RT/Pancake dies for
the bead halves, so the whole project together will be fairly
interesting.
Dar Shelton
SHELTECH