Bending a bracelet using HSM Thin Walled Pipe technique?
Hi -
I’ve completed the piercing on a somewhat delicate pierced bracelet
(think filigree but pierced), Now it’s time to take a deep breath
and start bending on the hydraulic press with appropriate dies and
lots of annealing. I’m thinking this is more probable of success
than using a rawhide mallet and a mandrel.
To try to maximize the potential for victory, I’m thinking of trying
to apply a version of the thin wall tube bending process (filling
with Cerrobend or something similar, maybe pitch). It’s a different
process because of the horizontal nature of the fill (flat, instead
of a tube). I’m having a struggle regarding how to fill a flat piece
with a heated material. The best idea I’ve had so far is simply to
try1000 mile an hour tape, fill with sand, tape the other side and
bend. The issue with sand is that it would be really hard to
unclog the verysmall cutouts after applying the pressure. Perhaps
some sort of powder, very fine sand…
Any suggestions? One member suggested bending the bracelet first and
then piercing, but I couldn’t figure out how to make that work for
my application (the angles seemed to prevent any useful lengthof saw
stroke very quickly).
Hi, If you are using a standard bracelet mandrel, perhaps sandwich
the bracelet between to similar blank strips, not pierced, maybe
tape the edges. Then gently put your hands around and push around
the mandrel??? If you need more leverage maybe use a wooden 2x4 or
metal bar and try to weigh down on it.
sound very crude but may work. try on a test piece. you may need a
helper to hold it. Watch your fingers…
In olden days they supported weak areas with shellac.
Sorry Bob, but you should have listened to the first guy. No matter
how carefully you try to bend your filigree will distort on bending.
The shapes will change and it will not bend uniformly. I am assuming
that you are using a non ferrous metal like silver copper, gold or
platinum.
You can saw pierce on a curved surface. It just takes more time and
effort. We regularly ajour on rings which is a pretty tight curve.
It just takes practice.
If it was me (and my experience is very limited so take this for
what it’s worth) I’d sandwich the filigree between two sheets of
similsr materiel half as thick as the original piece, and seal them
together, and fill the gaps with ‘orange’ shellac, this would support
the gaps when bending, and come undone with heat and/or soaking. HTH,
Betsy (not much seen in these parts of late)
Analogous situation. I was making brass bands to protect the leading
edge of the stems of my small boats. These were to be gently curved
strips of brass 1/4 inch thick and 1/4" wide. The band was to be
attached to the wooden stem by small screws spaced about 3 inches
apart. Lots of holes to bore. It would have been easiest to bore the
holes while the brass was straight. Could have set up a little guide
on the drill press table, slid the band along from hole to hole,
well supported on the flat surface. Then I would have ended up with
a piece of brass I had to bend into shape and it would have had a
weak spot every three inches where each hole was. It would have been
impossible to get a smooth, even curve by trying to bend the band as
a whole. Whatever the force I applied, whether by hand or any kind
of clamp or press, the discontinuities in the cross-section of the
band at each hole would mean the bend would be sharper at those
points. So I made the bends first, before boring holes, tacked the
band in place on its curved substrate and then bored the holes with
hand-held drill Obviously the boring portion of the job was a bit
more time consuming than if I had done it on the drill press with
straight stock - but trying to make an acceptable bend AFTER making
the holes would have been far more time consuming, if not
impossible. Your bracelet - although I don’t see a picture of it -
probably presents an even more difficult problem because it is
clearly not sane to make a complex pierced design after it is bent
into shape - as you say, very short saw and saw strokes needed. And
the differences in cross-section at any given point along the length
of the bracelet will vary wildly, therefore the resistance to
bending will be different and you will never get a smooth curve if
you try bending it as a whole. I don’t think it will be nearly as
tedious as you fear using a rawhide or other soft-faced mallet to
bend the bracelet around a mandrel. If you tap gently and
methodically you will get easily perceptible feedback from the
workpiece at each point along its length as you see and feel how it
responds to the strokes of the mallet. SO you can “customize” the
force of the blows, adjusting the force, spacing etc to suit what
the metal is telling you at each point along the length. Your aim is
to create the curve one small bit at a time rather than all at once
by bending the whole bracelet. It is really NOT as hard or slow as
you think. If you try bending it as a whole you will almost
certainly create “kinks” as the weaker spot(s) along its length
suddenly give in and collapse before the heavier portions start to
bend. You will then still have to hammer out and blend in those
uneven areas, if possible, by localized hammering, probably at least
as much time and work as if you set out to hammer it into shape from
the start so you won’t have saved any time - Anyway, that’s how I
see it from your description of the problem. Good luck.
I do quite a lot of the Russian Filigree work. I’ve made several
bracelets. That said you over thinking what you need to do to bend a
bracelet with filigree work. The biggest work you will have are the
inner wires/filigree popping their solder joints. You need to be able
to listen for that tell tail pop of the wire when it comes loose, and
deal with it immediately. I used PVC pipe to bend my bracelet in
sections. You just use your hands at first to bend it into shape on
the ends. This can be hard on the hands if you don’t wear gloves. I
just slowly bend a little on each end, and form those parts, then do
a gentle curve in the middle to get more of an oval. Doing it this
way I didn’t anneal at all. After I’ve done the hand bending, I
finish up with a nice used rawhide mallet, or if I can’t find it,
(hubby uses it for who knows what) I will use a rubber mallet. That
is when I do the refining of the shape. Now if it is a thin bracelet,
not a wide cuff you can use a bracelet bending plier with plastic
inserts in half moon shapes to bend it. Trick with it is to never
let the plastic parts rest on the filigree wires. ALWAYS place the
pliers so they are resting on the outside gallery wires.
When bending with either method, the filigree wires will bend as the
gallery outside wires bend. No need to add separate support. Always,
always, always, listen. Listen for that dreaded pop. It is easeir to
deal with it in the beginning of the process, than at the middle or
towards the end. If you hear a pop, stop and find where the pop came
from. I paint the whole piece except the area where the soldering
needs to be done, with yellow ochre Then I make little mound with in
the rough shape of the bracelet out of investment, and let it dry.
After it is dry, I gently heat it until it gets throughly heated
through while brushing it with the torch. That half cooks it but
completely dries it out. You can now place your bracelet on this
support to do the soldering you need to do. Wash well with an old
soft tooth brush. Then pickle, and proceed as before.
Listening is the most critical thing you will be doing. It is not a
loud but a small little pop when one of the wires goes. Never put
pressure on the wires themselves. Always bend the outside
wires/gallery wires. Relax, it is not as scary as you think.
I would agree with the sandwiching of the piece between 2 sheets of
similarmaterial. You couls also cement the sandwich with pitch which
will fill the piercings and if you bend it slowly enough the pitch
will flow under the pressure. Nick Royall