Peter W. Rowe wrote:
On Sat, 14 Mar 2009 10:54:23 -0700, in rec.crafts.jewelry "FC..."
wrote:

Well those are both some pretty good points to consider...

Question regarding the 'Combo Mills or Wire Only Mills'.

What is it that you jewelers make the most of with the 'grooved'
portion of the rollers. I understand that they make Square and Half
Round wire... Is that correct ?

Depending on the mill, some of which don't have the half round grooves, yes.
Sort of. The most commonly used are the "square" grooves, but these don't
produce a true square. Their purpose is not to provide a final shape, but to
start with a larger piece, for example a long narrow ingot such as might be
produced with a wire ingot mold or the wire portions of a combination ingot
mold, and break those down into a narrower long wire that can then be finally
shapex with drawplates, usually to round wire, or to other cross sections as
desired. The shape they produce is a square but with cut corners. Not quite
octagonal. The reason is that the flats at the corners allow the product of one
set of grooves to fit into the next smaller grooves after being rotated 90
degrees, without producing a flange on the edge. You can, of course, use the
semi square wire as is, if it suits your needs, but usually it's a starting
point. Often, for example, one might then run it through the flat mill to
produce rectangle stock, if one is not drawing it into a wire with draw plates.
The half round grooves are less usefull, since they're not such a generic use.
But useful for producing half round stock, such as for ring shanks, without so
much filing, or the need to draw it down. Drawing wire with narrower sharper
edges, like shallower half round, or triangle, etc, is more difficult than
drawing round wire, and of course one must have the drawplates too. Probably
the most common use for the half round grooves is for ring shank stock, but of
course you can use it for anything you might want half round wire for...

What is it that proves so
indispensable with the wire portion of the Mill (or a wire only
mill) ? Does it allow you to make a 'particular type of wire' ?

Most jewelers work with both sheet metal and wire. having both capabilities
allows you to make both. Plus, making wire is sometimes easier than making
sheet metal, since in some metals (silver especially) getting defect free ingots
for sheet metal is trickier than for wire, where minor defects don't produce
blisters that ruin the final stock.

The combo mills have limited width available for sheet, so you make only smaller
pieces. If you work with larger sized jewelry pieces, that's a limitation worth
considering. Many commercial "bench" jewelers, however, rarely need the larger
size sheet. Similarly, the wire grooves on a combo mill don't start with as
large a size. So you need to start with a smaller diameter wire ingot. That
can be a bit more difficult to pour, and limits the amount of wire you can make
in a single length. Whether this is a problem depends on the type of work you
do. As said before, you can make almost any type of wire you wish because the
mill itself doesn't usually give you your final wire product (unlike with sheet
metal, where it does). You will still need drawplates and the means to draw
wire. But you need the mill first, since you cannot start with an ingot and
directly draw wire from it.

Having the ability to make your own wire is very useful. Among other things,
the cost to buy wire already made incurs higher manufacturing costs from the
metals suppliers than does sheet metal, so there are savings involved. And you
can use even fairly small amounts of scrap to produce usable amounts of wire.


Forgive my ignorance, but I've never used such a unit and was
wondering what you are limited to as far as Flat Mill only VS. once
that has wire making ability (either dual rollers or combo..). What
would I be missing exactly ?

The flat only mills simply give you more width to work with. That allows you to
make wider stock if you need it. Plus, without the grooves machined into the
rollers, the rolls are a bit stronger, flexing less under load. That can give
you more accurate sheet thickness, especially when rolling very thin stock, as
well as often allowing you to start with a slightly thicker ingot.

As Abrasha notes, two mills are much better than one combo unit (or one of the
double units with a single mill having two sets of rolls, one over the other.
But the cost for two mills is of course, double that of one, so the compromise
of a combo mill gives you much of the basic capability with just the cost of one
mill. Half round grooves, or the capacity some mills have of add on side rolls
for half round, triangle, or patterned rolls, give you added capability for
shapes that can be more difficult to produce without them. Not everyone uses or
needs those capabilities. The flat rolls and basic wire rolls are by far the
most useful capabilities.

But everyone's needs differ, as you can tell in part by the differences between
my comments and Abrasha's.

Hope that helps.

Peter Rowe

Id say for the small time user a combo mill will prove more useful.
I bought my Durston some 25yrs ago and its as good as the day i bought it
My need was to do production milling so I motorised it.
Has been fine.this way.
However when making tapered section material one needs to wind in
then reverse out. Then move down to the next groove and repeat.
So to do this I put the handle back on.
Cant do this if its motorised.
Since then I accumulated several mills all flat.
The last one has a big 3ft 50lb flywheel on the handle shaft. with a 5
to I reduction. rolls 5 by 2.5in dia.
Had to get them reground to produce a true straight roll.
Last year I had to mint 2500 commemorative plaques for a 40th
anniversary . the material supplied was 3in wide by .036in thick.70/30
lead free guilding metal.
On calculating the length needed to make this no the client supplied
material left me with 500 approx short.
Ie enough for 2000,
What to do?
Cant ask for more, so I motorised this latest mill, set up input guide
rails, cut 3ft lengths of material and rolled it down so it was 48in long.
Reduction to .027in.
Worked just fine.
From cutting the sheet in strips(5 off)
rolling, guillotining to length, hot drop stamping,
pickling, clipping then date stamping, total of 50 in each production
day of 6 hrs work.
If youve wondered as to the heating to dull cherry red. made a Davy
miners lamp principle of controlled neutral non oxidising stainless
steel gauze muffle. with hinged top. Can see when its the right temp by
colour . Remove with tongs drop stamp thne pickle rince neutralise dry
and stack.
Hope this is of interest.
Ted
Dorset
UK.