I remember a discussion a couple of years ago about someone wanting
to use a hydraulic press or a rolling mill to replicate a planished
surface. Does anyone remember this article? I’m wanting to do the
same on pieces of copper about 5" square. Any ideas?
thank you,
Marie Maretska
Here’s what I wrote earlier this year, some of which applies to the
question at hand.
The conclusion (and partial answer to the question) being that a
rolling mill is generally going to be more effective at making
textures than a garden variety 20-ton press, and perhaps manual
planishing might still be the most effective, best looking method,
without serious tooling expenditure, either for custom rolling
plates or rollers, or in presses with much more than 20-ton
capacity.
A 5" square area is a lot to try and form in a hydraulic press all
in one go. One approach might be to press smaller areas with smaller
tooling, and cover the 25 sq. in. in multiple pressings, but overlap
could be a problem. A 5" wide capacity rolling mill is a big one,
and creating 5" wide tooling for that is no mean feat, and having
custom rollers made woulod cost thousands.
What would I do if I wanted to make 5" square planished copper
pieces?. I have a 50 ton press, a 4" rolling mill, and some basic
toolmaking capability… so how would I do it for myself ?..
(pausing to think). First, I’d revert back to the question of whether
I would be effectively either embossing or coining the metal, and
that could be largely determined by the thickness of the metal;
whether it is thin enough to be bending to conform, or so thick that
it would need to be (effectively) coined. If it’s thin, I’d look more
into embossing with a press (although coining small areas in multiple
passes could work with thick metal). If it’s thick… (boy, 5" is a
lot to deal with !)… I’d think about making a hammer that covered
more area than one spot, a multi-tipped affair. I’d think about a
motorized hammering machine, and I’d think about making 2nd
generation hammered texture plates for a giant, massively powered
rolling mill, AND I wouldn’t rule out doing them the way I would
already be doing them, by hand, the slow, hard, but reliable way.
posted previously:
“I had to look these up in the Rio catalog online, just to see what
the deal was, because my first thoughts were along the lines of
“watchoo talkin’ 'bout, Willis?!, 4” TEXTURE plates for the
press!!!??? “. The thinking lines that developed from many
experiments trying to press fine-resolution imprints into sheet metal
with a hydraulic press; plenty of experience that told me you just
don’t press 16 sq. in. of TEXTURE into metal --which, in my mind, at
that point, amounted to the same process as COINING. Not without
about 100 tons , or a lot more, you don’t… and then I saw the
pictures of the plates onscreen, and was enlightened and relieved to
find them described as EMBOSSING plates, and the universe all made
sense again, because I know that Phil Poirier knows wtf he’s doing,
and I do know firsthand that you can EMBOSS with a plate that big in
a press that little. 50 tons is nice, and I use it all the time for
EMBOSSING larger blanked parts with wire designs on the order of
1/32” to 1/8” deep (with those spiffy one-step blanking/embossing
dies I make), but I suppose 20 tons is adequate for some
applications, and to smaller areas than 4" by 4" (as Phil knows what
he’s up to).
I am frequently surprised though, at how little 20 tons can do in
these and similar situations, when you really think it’s going to do
more. I’ve also become very aware of the difference between embossing
–which is effectively merely bending metal --, and texturing –
which is effectively coining, which is actually displacing certain
areas within a mass of metal from one spot to another. The former
forming method is relatively easy, and the latter generally requires
far more pressure. A 20 ton press is a very powerful tool, but you
may (or may not) be surprised at how effective normal, manual tools
are for certain things. Offhand , I think of doing what a rolling
mill does : you can’t put sheet metal in a 20, or 50 , ton press and
squeeze it thinner. Or what about flattening metal?.. you really
want the wrinkles out, you have to hammer it. No, this does not mean
it’s ok to use your BFH on your pancake dies!!.."
Dar Shelton
www.sheltech.net