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Triangular extension rolls for Durston Mills


#1

Slightly off topic, but related. Does anyone know of a supplier who
carries triangular extension rolls for Durston Mills? Sometimes it is
just easier to make what you need…


#2

I have an inexpensive (made in India) rolling mill that came with a
number of roller combinations to include two textured rolls. I too
use a lot of triangular wire and don’t need the textured rolls. I
have toyed with having someone machine a series of V grooves into
one of the texture rolls to roll triangular wire. My concern is that
one roll will be slightly smaller than the other and that the
difference in diameter might create a shear force in the metal and
become a problem later. Since I clearly don’t know what I am talking
about, I would appreciate other views of this plan. I realize that I
didn’t solve your specific problem, but if my plan works, these
mills are fairly inexpensive and might serve your need. Stay tuned.
Rob


#3

Hi Rob,

I don’t think the difference in OD will make that much difference,
in terms of shearing the wire going through the mill. But I don’t
think you’ll need to go to that extreme either.

If you have a rolling mill (like those cheap Indian ones) that comes
with a set of square wire rolls, just use one of them, and you’ll
have as close to triangle wire as you can roll. A true triangle will
have to be drawn down from there.

From what I recall of a discussion with a rolling mill guru some
years ago, the reason that square wire rolls have those flat bottoms
in them (so they give ‘square’ wire with beveled corners) is because
if the grooves are a true “V”, with a sharp bottom, the metal snags
in the very bottom of the groove for some reason. (A reason known to
someone, but not to me.) I surmise that it has something to do with
pinching, but that’s a guess.

Regards,
Brian


#4
From what I recall of a discussion with a rolling mill guru some
years ago, the reason that square wire rolls have those flat
bottoms in them (so they give 'square' wire with beveled corners)
is because if the grooves are a true "V", with a sharp bottom, the
metal snags in the very bottom of the groove for some reason. (A
reason known to someone, but not to me.) I surmise that it has
something to do with pinching, but that's a guess. 

That’s not it. The little bevel at the apex of the half square is so
that the wire will be narrower from top to bottom after passing
through the roll, than it is side to side. What this does is that
when you then turn the wire 90 degrees, so that newly narrower
dimension is side to side, it then can fit into the next smaller
groove in the rolls, without the corners being pinched into a
flange.

Remember what it looks like if you feed a wire through a square wire
mill, from one groove to the next, without turning it 90 degrees. You
get those thin flanges on each side since the wire being fed into the
groove was wider than the groove. The flats in the bottom of the
groove are to allow you to avoid getting that flange. Without it,
you’d have a bear of a time progressing from one groove to the next
without damaging the wire. In a well made mill, you don’t have to
adjust the rolls, but can leave them in contact with each other,
almost down tight (not so much that it requires extra force to turn
the mill, but almost).

Once through each groove, rotating the wire 90 degrees between each
pass. Now, many mills are not quite that precise, and it can be good
idea or needed with certain grooves in a mill, to go through each
groove twice, once in each orientation. But even then, it’s the
little flat facets that allow you to move to the next groove. Without
them, you’d be going through each groove multiple times, opening up
the rolls for each new size and gradually squeezing it down while
turning it 90 degrees each time, on order to avoid the flanging at
the cornerss. Much more work.

Peter


#5

I have used one side of the square wire roller set with a flat
roller, but the resulting profile is not what I need in some cases.
I can also buy a draw plate, but I have yet to set up a bench to
securely hold one. My real need is for double triangular wire to
replace the bracelet base that I have been making for years.
Currently I take two pieces of 2X4 triangular wire, file one edge on
each and solder them together along the filed edges. I would like to
see if I can have one of the textured rollers that I don’t use be
machined to roll this stock out from either double half round or two
pieces of round wire soldered together. Any ideas are appreciated.
Thanks. Rob