rolling then drawing

My rolling mill has the customary series of 90 degree 'v' grooves for
rolling 'square stock'. The bottom of the groove has a flat so that the
final result is a square-ish octagon instead of a square.

That's not a complaint, just an observation.

When I take the resulting wire and begin to draw it round, I often get
'rags' along the corners. Makes for lousy jump rings.

What trick am I missing a here?

I'm gonna try to roll it to a more even octagon by turning it 45 degrees
in the roller. Maybe that'll help

My last attempt in sterling got pretty raggy while rolling and I had
some small success with heating it to fusing temp (well I think it was,
the surface went liquid-looking and a little bumpy) to stick the rags
back down.


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On Wed, 08 Sep 2004 00:14:25 -0700, in hõ Carl West
wrote:


My rolling mill has the customary series of 90 degree 'v' grooves for
rolling 'square stock'. The bottom of the groove has a flat so that the
final result is a square-ish octagon instead of a square.

That's not a complaint, just an observation.

The little flat is there for a good reason. It allows you to rotate the wire 90
degrees, and when you've done that, the two little flats just rolled are not side
to side, making that horizontal dimension narrower, so it then fits in the next
smaller groove without creating a "fin" along the edge. Be very sure, when
rolling, that you don't create such fins, as they roll back into the wire
creating a longitudinal crack, which can then behave just as your problem wire is
doing. In the event you get such a fine, file it off before proceeding to roll
again. A well made mill, however, if your final roll through a given groove has
the rolls down tight to each other, should produce wire that will then go as
described in the next hole, still with the rolls tight together, giving no fins.
Be sure to run the wire in both orientations on the final roll, so it's got those
little flats, as they help with drawing.


When I take the resulting wire and begin to draw it round, I often get
'rags' along the corners. Makes for lousy jump rings.

That can have several causes.

First, a bad ingot in the first place. If your ingot isn't solid, but has voids
or serious porosity, it may roll just fine, but when you try to draw it, the
problems show up. Oxides and fire scale can do this to. And while high karat
gold or fine silver works fine with those open topped grooved ingot molds,
sterling silver and lower karat golds tend, especially with the rougher cast
molds rather than the machined ones, to give an ingot who's top surface is rather
rough and irregular. It can be quite hard to roll that into good wire, since the
irregularities sometimes give rise to micro cracks and tears. Again, these don't
show up in rolling, but certainly do in drawing. If you've got such ingots, it
may help to file off the surface roughness before rolling. At the least, pickle
well, and then anneal frequently at the first sign of work hardening until the
ingot has become uniformly shaped.

Second, during rolling, if you go too far without annealing (hard to do with good
sterling) it can create small cracks and defects that will sometimes not show up
in rolling, but will during drawing. Note too, the common problem that occurs
when a fin is formed during rolling due to wire too wide for a groove. If you
have a groove in your mill that won't roll smoothly from wire straight from the
next larger size, when rotated 90 degrees, you may have to open the rolls alittle
and run it through that hole in several successive passes till the rolls are
closed up again, to avoid getting that fin, and this process may also be needed
with the first few large grooves, if the ingot is too heavy to just roll all in
one go with the largest groove.

You may also have an overly rough drawplate. Some less expensive steel plates
have transitions between the initial tapered "feed in" sections of the holes with
the actual drawing taper, and the end trailing edge of that drawing tapered part
of the hole, that are just too sharp. they can, especially if not well
lubricated, tear the wire. A little polishing compound on a toothpick in your
flex shaft, to polish those sections of the holes, will provide a smoother draw,
and less tearing.

The one thing that is NOT likely to be doing it is the difference in size between
that small flat and the larger square surfaces, so long as you've rolled the wire
through the final groove in both orientations, so you've got those little flats
on all corners. The angles between faces is what's important here, not the
size of the faces.

Do be sure you're lubricating the wire (beeswax, bur life, etc), and be sure to
start with a large enough hole that the wire loose those flats in several steps.

sometimes, if during initial drawing, you see a few small splinters forming, you
can sometimes pull the wire a couple times through a small folded bit of emery
paper to smooth off the splinters, or use a scraper to remove them. If they are
not serious, you may then be able to continue drawing. But as often as not,
you'll find the splinters are just the tip of the icerbug, and the cracks
actually run deeper into the wire.

For me, the most common cause of bad wire when drawing is a bad ingot in the
first place. I find the closed ingot molds to work a lot better. You know the
type. Sliding mold that makes a sheet ingot on one side, reversed to assemble
with a serious of holes into which you pour the metal. Generally, you'll get the
best results with the largest ingot size you can still get into your rolling
mill.

Hope that helps.

Peter


What trick am I missing a here?

I'm gonna try to roll it to a more even octagon by turning it 45 degrees
in the roller. Maybe that'll help

My last attempt in sterling got pretty raggy while rolling and I had
some small success with heating it to fusing temp (well I think it was,
the surface went liquid-looking and a little bumpy) to stick the rags
back down.

Carl West wrote:
My rolling mill has the customary series of 90 degree 'v' grooves for
rolling 'square stock'. The bottom of the groove has a flat so that the
final result is a square-ish octagon instead of a square.

That's not a complaint, just an observation.

When I take the resulting wire and begin to draw it round, I often get
'rags' along the corners. Makes for lousy jump rings.

What trick am I missing a here?

I'm gonna try to roll it to a more even octagon by turning it 45 degrees
in the roller. Maybe that'll help

My last attempt in sterling got pretty raggy while rolling and I had
some small success with heating it to fusing temp (well I think it was,
the surface went liquid-looking and a little bumpy) to stick the rags
back down.


--
Carl West http://carl.west.home.comcast.net

change the 'DOT' to '.' to email me

"Clutter"? This is an object-rich environment.
What your getting is a flash that forms in the rolling process.
there are several things you can do
1. Is to turn the wire through 90 deg inbetween each pass through the rolls.
2. dont screw the rolls down tight against each other when rolling, If
you do youll get a flash pushing out sideways.

Iif I get that problem, rarely nowadays, ill linish it off before going
on to draw to round. wire.
..
how many passes you need to make in each groove will depend on your
mill. On a 2 roll machine say on a 5in wide roll youll have 2.5in of
grooves and 2.5in of flat.

If you can afford the 4 roll machine youll have all 5in as varying size
grooves which will enable you to make one pass in each as well as one
set of rolls all 5in wide for sheet.
Need some turning by hand. !!
Experiment with copper wire if you can find some 1/4in dia, heavy
transformer wire from your local metal scap yard is the best pl;ace to
find it by the cwt.
what size wire are you aiming at?
Let us jknow how you get on.

I can't add anything to what Peter said other than moral support but having
just been there with my homemade mill, I wanted to enter the discussion.

I didn't quite understand the purpose of the flats the first time Peter
described them to me but having added them to my mill and what he just said,
it all makes sense now. I also understand why I still have the fin problem
if not very careful. Not enough steps.

I was also surprised to learn that you do not have to anneal sterling as
often as fine but I can't roll sterling in my mill anyway at least at the
ingot stage. It just is not robust enough.

You may want to try fine silver just as an exercise as it is much easier to
roll. However, frequent annealing is a must but this could also be a
problem unique to my mill. I do not have as many holes to work with on this
prototype, only 4 steps from 1/4" to about .070" where I switch to the
drawplate. This makes it rather tedious and I am making a new set of roller
with more grooves.

I find that if I only roll to the point where I need 3 passes through the
drawplate, I get very nice wire. Any less leaves rough spots. Lube is
important but I find motor oil works as well as anything and I anneal before
the last hole.

I find it very rewarding to take a piece of silver and turn it into wire of
any size and thence on to a beautiful chain. Right up there with learning
to fly.

js


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Peter W.. Rowe, wrote:

... A well made mill, however, if your final roll through a given groove has
the rolls down tight to each other, should produce wire that will then go as
described in the next hole, still with the rolls tight together, giving no fins.
Be sure to run the wire in both orientations on the final roll, so it's got those
little flats, as they help with drawing.

Ah. Mine is coarser than that. Opening the rolls is required when going
to the next groove. It tries to produce a fin every time. I roll in
one direction, turn 90 degrees roll again, _then_ tighten the rolls for
the next pass.


When I take the resulting wire and begin to draw it round, I often get
'rags' along the corners. Makes for lousy jump rings.


That can have several causes.

First, a bad ingot in the first place. If your ingot isn't solid, but has voids
or serious porosity, it may roll just fine, but when you try to draw it, the
problems show up.

At some point I'll make myself a proper mold. I have the graphite for it...


The one thing that is NOT likely to be doing it is the difference in size between
that small flat and the larger square surfaces, so long as you've rolled the wire
through the final groove in both orientations, so you've got those little flats
on all corners.

The rags _appear_ to be from the small flats being mushroomed out over
the larger faces. Could be hidden rags from squashed fins showing up.
Hmmm... more experimentation is in order...


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change the 'DOT' to '.' to email me

"Clutter"? This is an object-rich environment.

On Wed, 08 Sep 2004 07:47:19 -0700, in Ìõ Carl West
wrote:


At some point I'll make myself a proper mold. I have the graphite for it...

Graphite is a fine mold material but can be difficult to pour in a narrow wire
mold, since the graphite is such a good heat conductor that the metal almost
freezes on contact. Personally, I find the machined iron/steel molds to produce
the best results. The surface of the mold is very lightly oiled, or is coated
with soot (from a torch flame that has had the air/oxygen cut off, so it's very
yellow), as a lubricant. Of the two, I prefer oil. easier, and then when
preheating the mold, you have an indication when it's hot enough, as the oil
start to smoke.



The rags _appear_ to be from the small flats being mushroomed out over
the larger faces. Could be hidden rags from squashed fins showing up.
Hmmm... more experimentation is in order...

I'll bet the latter is the case. Surface defects from oxides or a bad ingot can
look the same. Be sure the ingot is clean and smooth before rolling in the first
place, and do not allow it to form grooves or fins during rolling.

Peter

On Wed, 08 Sep 2004 07:47:15 -0700, in ¸õ Jack Schmidling wrote:

I was also surprised to learn that you do not have to anneal sterling as
often as fine but I can't roll sterling in my mill anyway at least at the
ingot stage. It just is not robust enough.

Jack, not sure where you got this from. Fine silver is more malleable and
ductile than sterling. You do not need to anneal it as often as sterling.
Note, however, that my statements as to how often you need to roll it are based
on how far the metal can be rolled or drawn before it fails from internal
stersses, not on how difficult it may be to roll. If you find you need to anneal
fine silver frequently to be able to work it with your equipment, then you'll
need to anneal sterling more often, as it work hardens more quickly. However,
this need will be based just on the softness and ease with which the metal can be
worked, rather than the need to prevent failure of the metal. Drawing wire
generally will need annealing more frequently than rolling it, but as a general
rule, silver (either sterling or fine), can be reduced in cross sectional area by
as much as 90 percent between annealings. That figure is what's used and
published by Handy and Harmon in their industrial settings for production. You
may find you need to anneal a bit more often. But there it is...

Peter

On Wed, 08 Sep 2004 07:47:10 -0700, in ¤õ Ted Frater
wrote:

2. dont screw the rolls down tight against each other when rolling, If
you do youll get a flash pushing out sideways.

Ted, this depends a lot on one's own mill. But at least with the Cavalin Mills,
and the Durston wire mills I've used, the size step between rolls is chosen by
the manufacturer so as to see that the horizontal dimension of a groove is very
slightly greater than the vertical dimension of the next larger groove, when the
rolls are tightly closed. That, in theory, allows the rolls to never be opened
at all, stepping from one groove to the next with a 90 degree turn. The math no
longer works if the rolls aren't tightly closed, and of course, there's nothing
actually wrong with stepping through several settings with each individual groove
if it's found that is what's needed for your mill, and the metal you're rolling.

Peter

Jack Schmidling wrote:


I was also surprised to learn that you do not have to anneal sterling as
often as fine


It's the other way around. It is not necessary to anneal fine silver (or fine
gold) at all, while rolling or drawing. I roll and draw fine gold almost
daily. I never anneal it once, from ingot to final diameter, which is .8 mm or
1 mm for rivet wire or 1 mm square for wire inlay. In fact, if you anneal it,
it always breaks in the draw plate. Or at best stretches inside the draw plate
instead of being pulled through a hole.

Abrasha
http://www.abrasha.com

"Peter W.. Rowe,"

Jack, not sure where you got this from. Fine silver is more malleable and
ductile than sterling. You do not need to anneal it as often as sterling


It was the way I interpreted the statement....

Second, during rolling, if you go too far without annealing (hard to do
with good
sterling) it can..........

I assumed the coparison to fine... sorry Teach.

js


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