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Karat Rolling Mill


#1

Hi all!

I have recently purchased the inexpensive, imported from India, Karat
Rolling Mill. So far it is working well. Until I tried to roll a sheet
about 3.5mm thick. It seems that the gears are spread too far apart at
that width and start jamming up. This seems like a very silly question but
I will ask anyway: is there perhaps a trick that will get it to roll a
thicker piece without jamming up? Also, is 3.5mm a common largest width
for rolling mills or is it just my inexpensive machine?

Thanks.

Jill
jill@jjewelry.com
http://www.jjewelry.com


#2

Jill: that seems like an awful thick piece of metal, it would take a long
time to roll it down to useable size, my ingot mold makes about 3mm thick
ingots. My advice would be to anneal and hammer it down thinner. Anneal
again and then roll and make sure you anneal often. If you pickle after
annealing make sure you dip into water with baking soda to neutralize the
pickle or you’ll etch and stain your rollers. There’s no trick I know of
for the rolling mill, at that height the teeth aren’t meshing. Hope this
helps…Dave


#3
        I have recently purchased the inexpensive, imported from India,
Karat Rolling Mill.  So far it is working well.  Until I tried to roll a
sheet about 3.5mm thick.  It seems that the gears are spread too far
apart at that width and start jamming up.  This seems like a very silly
question but I will ask anyway:  is there perhaps a trick that will get
it to roll a thicker piece without jamming up?  Also, is 3.5mm a common
largest width for rolling mills or is it just my inexpensive machine? 

There is no trick for making a rolling mill work with thicker sheet than
it was designed to.

The more expensive rolling mills are worth the investment.

Most of them will handle a 6mm thick sheet and some will handle a 9mm
sheet.

I bought a used Cavillin combination rolling mill a few years ago. I lucked
out and picked it up for $200 they are $800 new.

Timothy A. Hansen

TAH Handcrafted Jewelry
@Timothy_A_Hansen
http://www.home.earthlink.net/~tahhandcraft


#4

Dear Jill and Richard, I believe the thickness of the material you can
roll in a mill is related to the diameter of the rollers themselves. I
just ordered a dursten mill with 60mm thick rollers and it will take up to
7mm. Vince, Eugene, OR.


#5

Hi Jill,

It’s really important when considering the purchase of a mill to look at
the maximum thickness for sheet (and for wire if it does wire too). And
for just the reason you mention. The gear can chip and break if they are
too far apart when you roll something through the mill.

3 to 5 mm maximum sheet thickness is common for most hand rolling mills.

Many ingot molds however make 3.5 mm ingots. If your mills max thickness
is 3.0, the best thing to do is to grind down the sides of the ingot mold
so that it makes an ingot of 3.0mm or less.

Hope that helps. I would be hesitant about tricks to “forcing” the mill
to do what it is not designed to do. Could break the gear teeth.

Best Regards,

Elaine Corwin
GESSWEIN CO INC USA
Tech Support: 1-800-544-2043 ext 287
Tel: 203-366-5400


#6

Other rolling mills do accommodate billets thicker than 3.5mm so your
machine does have a rather limited capacity. I have a 120mm wide 4:1
Cavallin and I’ve done 6mm thick pieces with it. And yes, the 4:1 gear
reduction is invaluable, especially for this kind of thick stock. Donna


#7
Many ingot molds however make 3.5 mm ingots.  If your mills max thickness
is 3.0, the best thing to do is to grind down the sides of the ingot mold
so that it makes an ingot of 3.0mm or less.

One other way to decrease the size of the billet that’s not as wasteful of
material as grinding, is forging. The billet is relatively soft in it’s
normal state after cooling. Place the billet on an anvil or solid steel
surface that’s well supported. Use a heavy (2-3 lb.) hammer with the wide,
flat face to forge the billet thin enough to go through the mill. Work the
billet evenly to leave the surface as un-dimpled as possible. If there’s a
thick (3/4 in. or greater) piece of flat steel available, it could be
placed on top of the billet & the hammer applied to that. Depending on the
reduction necessary, the billet may have to be annealed after forging &
before rolling.

If more billets will be made for rolling in the future, the mold used to
make them should be marked with a depth indicator indicating the height to
which billets intended for rolling are poured.

Determine the depth (D) of your mold at the deepest spot. Subtract the
mill roll opening distance (O) from this number. The result is the distance
from the top (T) of the mold a mark should be placed. The formula is D - O
= T.

When making the roll opening measurement, be sure the teeth stay meshed
for the entire circumference of both gears. How much the gears need to be
meshed depends on the contour of the gear tips. If the gears do not mesh
sufficiently, they’ll wear more at the tips & have a tendency to try to
climb over one another. If they climb over one another there’s every
probability of serious damage to some part of the mill.

Use a scribe or cut off blade to incise a mark along the inside of the
mold for the full length at a distance ‘T’ down from the top of the mold.
The line only needs to be deep enough to be easily seen while pour billets
for rolling. When pouring billets that will be rolled, stop pouring when
the line has been reached. The line won’t interfere with casting billets
that are thicker than rolling billets.

HTH,

Dave