Can anyone tell me why, when making a jump ring coil of square wire,
it always wants to bend on the diagonal instead of the flat? For
that’s where the metal is thinnest. I wanted a lot of little rings of
the square wire to fit into a space as part of a necklace. I was
winding a coil of 0.85mm square annealed sterling on first, a pair
of round nosed pliers to find the right size former, then winding the
3 cm long coil on a piece of 2.2 mm brass wire as a mandrel this
afternoon, and I was forced to remember that the wire invariably turned
itself over, to bend so a corner of the wire points outward. OK, I
had no problem after I threaded the wire through the last die it was
drawn through, to present it to the slowly rotating mandrel and it
wound on the flat (I’d forgotten that earlier!) But physics and
engineering experience suggest to me that it should PREFER to wind on
the flats! Silly answers, anyone? Part of Murphy’s Law, I suppose.
Cheers, John Burgess
Square wire bends on a diagonal axis because this allows a larger
section to remain unaltered by either stretching or compressing, and
smaller sections to stretch (inside of the bend) or compress (outside
of the bend). It’s the path of least resistance.
Bending square wire on the square requires that the full width of the
cross section be compressed and stretched as opposed to just corners
when it’s bent on the diagonal.
It’s the path of least resistance.
Dick
Here’s one answer John - It all has to do with Pi (I can’t do the
Greek letter), and differential stretching. The same thing happens
with round wire, but you’d need an x-ray to see the effect (or you
could scribe a straight longitudinal line down the wire, and see how
long it takes to twist around one circumferance). Basically, you’re
wrapping in a spiral, which means that there is differential
stretching in two directions. This comes out as a spiral bend if the
wire is free to follow that path. (DNA-ish?) I’ve been making square
wire links since the 60s and would welcome any practical way to damp
down this effect. Taking my time, and making certain that the wire is
dead soft to begin with seem to be the two sovereign remedies. I
almost always have to planish each link when I’m done, anyway.
Jim Small from SMALL WONDERS
Hi John, One apparent cause of square wire spiral is the rotating
motion of the hands. In order to hand coil ones hands do not stay in
the same plane. They are rotating in a spiral pattern, resulting in
the twisted wire. A draw plate guide prevents the introduction of a
spiral twisting in the stock. Another possibility is the twist already
in a coil of wire used for stock. In order to coil any wire
hose(garden etc) one must introduce a twist. This allows the coil to
lay flat and even. Other thoughts?
Marcus Amshoff
Hi John,
Boy, it sure is fun to be able to offer some help (maybe) to one of
the ‘best helpers’ on the list!
I’m not sure this has any basis in fact, but it’s my supposition as
to why this happens. Metals, even when annealed, want to remain in
their present form or shape. When forced into some other shape,
they’ll assume a shape that requires the least movement on their part.
Unless of course, they’re constrained from taking that path. When
winding square wire into coils, the wire wants to assume the on edge
position because that requires the least amount of material to move to
the extreme positions (outside & inside of the coil).
Don’t know if that idea stands up to scientific scrutiny, but it’s a
place to start.
I wind lots of wire shapes other than round into coils for rings (I’m
a chain maker). I’ve made a wood clamp to guide the wire onto the
mandrel. It allows adjusting the tension on the wire as well as
controlling the lay of the wire on the mandrel.
Dave
John, Of course I had to read your post before going to bed and
totally buggered up any hope of getting any sleep with this on my
mind. 
I would have to say that it is due to the natural rotation
of the metal being wound around the mandrel. If for example one was to
take a wedding band of square section and cut it, for all sense of
purpose we now have a jump ring. If we then were to split this
sideways and look at the end we would see a slight rotation of the
square section leaning downwards from the centre line or axis of the
link. If we were to measure that angle from a centre line taken
vertically and it was lets say 10 degrees, then it would also be 10
degrees on the other side making a total of 20 degrees. Now this angle
is taken from two edges that were coincident before the split,
therefore taking into consideration that the twisting could in fact
be greater than the 20 degrees and being probably closer to 45 degrees
around the whole circumference would explain a possible reason for it
to twist onto an edge. The heavier the gauge, the larger the
probability. of a larger twisting angle. The fact (as you mentioned)
that the metal has less metal on the edge could contribute to the ease
of flow of the twist onto an edge. Another possible scenario, or a
combination of both is that metal to the inside of a curve reacts in
an opposite direction to the outside of a curve. If we look at (not
the curve that touches the mandrel) the curve as the material lines
up edge to edge along the length of the mandrel, is it feasible that
the inside curve has less distance to travel lets say than the outside
due to the rotation?. This would therefore possibly show that the
outside curve is trying to lessen the stress by equalling the pressure
with the inside curve with a 45 degree twist. This twist would make
both the inside and the outside curve, now curves that are not only
equal but come off the surface at a 45 degree tangent. Hope this
makes sense…(very interesting post John.) Wow that’s it for me. Best
Regards. Neil George
John, I would think that as you are winding the wire it would need to
kept at ninety degrees to the mandrel to prevent twisting.
Steve
But physics and engineering experience suggest to me that it should PREFER to wind on the flats! Silly answers, anyone? Part of Murphy's Law, I suppose.
I think the answer may lie in the fact that in metal under tension
the greatest shear force occurs at a diagonal … think tension
failure.
Shawn
Hi Jim,
Here are the instructions to make a small guide from wood to be used
when coiling square wire. The dimensions aren’t really critical, so
they can be adjusted to suit the available wood supply. That’s
provided you don’t go so large as to make the tool cumbersome. 1/4
inch thick lattice or large paint stirring paddles work well.
Construction:
1. Cut a piece of wood 6 x 1 1/2 x 1/4".
2. Cut a piece of wood 3 x 1 1/2 x 1/4".
3. Mark a center line the long way on the 3 " piece.
4. Place a mark on the center line 3/8 " from each end.
5. Cut a notch centered in the end of the handle about 1/8" wide x 1/4" deep.
6. Place the 3" piece over the 6" piece with 1 end flush with 1 end of the 6" piece.
7. Tape the 2 pieces together with masking tape. Don't cover the 2 marks.
8. Drill a 3/16" hole through the 2 pieces at the marks.
9. Insert a suitably sized machine screw (8-32 or 10-32 x 1") through the 2 holes.
Insert it so the screw head is against the 6" piece.
10. Secure the screws with a wing nut to facilitate tightening & loosening.
11. Sand all wood edges to remove any splinters. If desired, the expose end of the
6" piece can be shaped into handle to make it easier to hold.
Use:
-
Place the wire to be coiled between the 2 pieces of wood so it
passes to the right of the front screw, to the left of the rear screw
& through the slot in the handle. -
Depending on the shape of the wire, square, 1/2 round or
triangular, and the desired position of the flat side in the coil,
place a flat side against the appropriate part of the tool. Adjust the
wire so about 1" protrudes from the front of the tool. -
Tighten the wing nuts loosely, to keep the wire in the selected
position. -
Attach the end of the wire to the mandrel.
-
Slowly turn the mandrel until the wire guide contacts the mandrel.
-
Leaving an edge of the guide in contact with the mandrel while
wrapping the coil facilitates any required adjustments. -
Watch the lay of the wire while coiling. If the wire begins to
twist, Rotate the wire guide in the opposite direction to correct the
problem. -
If several wraps have twisted before the error is noticed, uncoil
those wraps by reversing the mandrel direction & holding the uncoiling
wire taut with the guide. -
Re-wrap the wire by carefully guiding it onto the mandrel until
the guide again is in contact with the mandrel.
Holding the tool so the handle is on the bottom allows the wire
supply to pass between the heel of the hand & the handle. With the
tool in this position, it’s easy to adjust the wing nuts if more or
less tension is required while winding.
When tightening the wing nuts, the tendency is to over tighten. This
makes it difficult to wind even coils. A little experimentation will
help determine the correct adjustment. Generally, the rear wing nut
can be a little looser than the front.
If the edges of the tool become worn through repeated use, turning
the pieces over will expose an unworn surface.
If you want to make the tool from metal, a thin piece of leather can
cemented to the working sides of the guide to prevent marring the
wire.
Dave
Dave: would you have a picture of said wooden clamp? Or could you
describe it? It’s a fabulous idea… if I could only figure out
what it meant! thanx, rhoda
Moderator’s comment: Use the Orchid FTP to upload pictures to the Orchid site
Hanuman
ting mandrel and it wound on the flat (I'd forgotten that earlier!) But physics and engineering experience suggest to me that it should PREFER to wind on the flats! Silly answers, anyone? Part of Murphy's Law, I suppose.
No, John. The same physics and engineering. You’re visualizing what
happens wrong, I think. when you bend wire, the outside periphery
stretches, and inner surface compresses. The wire wants to maximize
the portion of the wire along the center line, where it neither
stretches nor compresses, while minimizing the part that most compress
the most or stretch the most. Bent on the flat, the portions that
compress the most and stretches the most are equal to the center
section that does neither. On the diagonal, with only the points
compressing or stretching the most, these areas are less than the mass
along the center diagonal cross section which must only bend. Thus
bending on the diagonal, less material must stretch at the outer
periphery, and less material must compress at the inner diameter. As
a result, it takes slightly less force to bend the wire on the
diagonal, thus this is the way it will try to form itself.
Conservation of energy… Did I tie that explanation into suitable
verbal knots? (I tried)
Peter Rowe
G’day John
Yes, I’ve had the same experience with square wire and also wondered
why it tends to kink. I spoke to an engineer specialized in wire
etc., who also knew of the problem and he suggested it derives from
the fact that one is not exactly making a circle but more a spiral
formed thing (like a thread in a bolt or screw), and that is the
nearest I could get to an answer, unless - as you suggests, it is
Murphy’s law in action.
Kind regards
Niels L�vschal, Jyllinge, Denmark
@L_F8vschal
Hi Rhoda,
would you have a picture of said wooden clamp? Or could you describe it? It's a fabulous idea... if I could only figure out what it meant!
Sorry, I don’t have a picture. If the instructions I posted (probably
after your post) don’t clear things up, send me a msg off list & I’ll
see if I can help.
Dave
Anyone else want to join me and spend a day at Dave’s side. Bet we
could convince him to hold a class for us link makers, chain makers,
etc.
David I have watched your many helpful post for quite some time now.
I know you both sell and teach yet you never put any of that in your
replies. I recognize and appreciate that. How many do you teach at a
time, and when are you available?
There are many “special fares” into Tucson on Southwest and other
Airlines. I know others may be interested.
Teresa
Can anyone tell me why, when making a jump ring coil of square wire…
Try twisting the square wire before you wind it around your mandrel.
Twist in the opposite direction from the way you’ll wind the rings on
the mandrel. Do it by hand, holding one end in a collet chuck and the
other end in a vise. This allows you to control the amount of twists
per inch. Make each complete twist the same length as the
circumferance of the mandrel. Anneal the wire EVENLY before you twist
as well as prior to winding the rings.
Ken Weston
I had posted the technic I use to obtain a coil of square wire rings
many months ago.This really works well and is equally useful for
winding 1/2 rd wire. Place the size mandrel you desire into a vice or
the jaws of a hand drill held in the vice. Feed the wire thru a draw
plate (square one for square wire) so it goes thru easily, but not
too loose. Holding the plate against the mandrel, either crank the
drill or turn the plate so that the wire is fed onto the mandrel
without twisting.
This works very well, but if you have problems, E-mail me and I’ll
happily walk you thru it again. @DrDule