Compiling instruction guide for rolling mill

Jewelry Discussion
1

Hi All, I have access to a rolling mill through a lapidary club &
just had the rollers resurfaced because someone had used it
improperly but now everything is as good as new.

I want to make up a instruction guide for students to follow so
these rollers don’t get damaged again. The mill was bought used with
no instructions for use or maintenance.

Any info you have that I should include would be very helpful. Also
when you use 2 pieces of brass sheet to sandwich your silver &
pattern material with what gauge of brass is preferable and you don’t
anneal it, right?

Can I just pick up a couple of sheets of like 28g. brass at the
hardware store to use for the sandwich?

2

Gaylen, When I was taking classes at a community college, they used
Plexiglas to sandwich the metals, probably less than 1/4 inch. Teresa

3

Gaylen,

Here’s what I would suggest:

  1. Keep a can of 3-in-1 oil sitting by the rolling mill at all
    times. Each person is to oil the rollers before and after they use
    them. No exceptions. Keep some gauze wadding (which will quickly be
    oil soaked and gross-looking) laying on the rollers when they are not
    in use, and use that wadding or paper towels to do the oiling.

  2. When not in use (like overnight), roll the oil-soaked wadding in
    between the rollers (not squeezing – just enough to keep in contact
    with both rollers).

  3. No ferrous metals go through the rollers under any circumstances

  4. No “patterning” materials go through the rollers without being
    sandwiched.

  5. No wire goes through the mill on the sheet rollers unless it is
    fully sandwiched.

  6. No one adjusts the individual wheels that align the rollers
    except an instructor or lab manager. Realigning them is a real pain,
    as I’m sure you know. The only wheel that others get to adjust is
    the one that adjusts the overall pressure.

  7. We use nickel silver, rather than brass for our sandwiches.
    Seems to work better in transferring the pattern, because it’s
    harder, which forces more of the design toward the metal being
    imprinted. But either way, we keep a little bucket of sandwich
    pieces sitting by the mill. You simply pick out the pieces that best
    fit the piece you’re imprinting. Those pieces probably started out
    18G, but are now somewhat thinner. When they get too thin (i.e.,
    holes or cracks in them), we toss them in the scrap bucket and get
    new pieces.

That’s about it in terms of rules for our mill. They seem to work
well. I hope they help!

Karen Goeller

4

Gaylen - If you go to www.Durston.com you can download their
instruction guide.

Janice

5

Gaylen I don’t really know anything about roller mill
maintenence–that’s why I’m responding! Do you know who/what kind of
place resurfaced the rollers, or what it cost? The ones where I
teach are a wreck. I’m considering tackling it myself, but would
rather not take a chance on making matters worse, and spending many
hours doing it! --Noel

6 
 Gaylen I don't really know anything about roller mill
maintenence--that's why I'm responding! Do you know who/what kind
of place resurfaced the rollers, or what it cost? The ones where I
teach are a wreck. I'm considering tackling it myself, but would
rather not take a chance on making matters worse, and spending
many hours doing it!      --Noel

Don’t know what kind of mill you have but Cavallin recommends that
both rollers be reconditioned at the same time. You can take them to
a machine shop and ask that both rollers be ground exactly the same
amount, then case-hardened to 0.040" (40 thousandths).

If your rollers have very slight scratches in them, you can remove
those yourself using some of the new microabrasive sandpapers
available today.

Elaine Corwin
Gesswein Co. Inc.
www.gesswein.com

7 
     I have always heard that an off centered grinder is the best
& most accurate method of grinding rollers to keep them in round?
Of course this has to penetrate the deepest marring & case
hardening would be required afterwards. Perhaps Matthew or Sara
Durston might enlighten us all?

Dear All, Not sure what is meant by “off centered grinder”. Maybe,
you mean “centreless grinding.” Centreless grinding does not
necessarily make parts “more round” as compared to regular grinding.
The important thing is - centreless grinding is no good for rolls as
the bearing journals must run true with the main diameter. When
grinding the main diameter between centres it is important that the
bearing journals are checked to make sure they are running true.

Back to the hardening. Good quality rolls are not normally made from
case-hardening steel. The “case” is relatively thin on case-harden
parts and as already mentioned this would cause the sub surface to
collapse under loading. If it were necessary to reharden the rolls
they must be annealed first according to the spec of the steel. They
can then usually be hardened again, although there is a risk that
they will crack. However, the hardening would distort the rolls and
they would have to have all diameters ground again. This will result
in undersized bearing journals as well as the main diameter.

Conclusion: Good quality rolls can usually be reground without the
need for rehardening. If rolls do become soft for whatever reason
i.e.: incorrect material used or wrong hardening procedure, then the
only answer is to buy new rolls.

Matthew Durston