A jeweller and goldsmith has to cut tubing fairly regularly. My favorite
methods include: cutting only on the upstroke using a jewelers sawblade;
using a separating disc; rolling the tube with high pressure under an X-acto
knife or sharp blade, then snapping the tube-this works pretty well as long
as you have good leverage..
Any nick or 're-entrant angle' with a triangular needle file, sawblade
etc will allow a tube to be snapped. The resulting break is not very clean
and best used if you follow up with a small belt sander. The longer the
remaining piece (thus the more leverage) the better this method is. If
your tube section is very short then slide a rod into the tube to gain
more leverage: then it will snap rapidly and easily.
A small tubing cutter may be made from an old file. I usually use my bench
pin but there are times when it is useful. Only cut tubing on the upstroke
and let the blade slide lightly in the slit on the down.
|possible tube cutting jig
Separating discs work very well for cutting tubing, both at right angles
to the tube as well as oblique cuts and notches for sharp angled tubing
Tubing can be cut while spinning when mounted in the flex shaft handpiece.
Span the sawblade in upside down in the saw frame and hold the handpiece
in your left hand with the teeth pointing away from the handle so that
the tube rotates towards you and into the teeth of the blade. When the
sawblade is held onto the tube it cuts it off. Assuming a three mm tube
more or less one leaves it about a maximum of 3.5 cm or so out of the
end of the chuck jaws. If it is longer there is some danger of it bending
while spinning. The tube can then be cleaned up with emery paper while
it is rotating and then marked to a given length with dividers. One can
them mark the tube again with the dividers or vernier callipers and cut
off another piece. This method offers speed and a guaranteed right angled
cut to the tube. If one is making tubing settings for a given size one
holds a ball burr into the rotating tube which cuts the seat for the stone
and then cuts the tube off to get a tube setting. If set up to make the
same size settings it can be as fast as one every three seconds to make
the seat and cut the setting off. As some stones like diamonds, synthetic
corundum and spinel will take heat as long as there is no sudden temperature
change one can even cut the seat into the tube with a round burr, place
the stone into the setting and then set the stone in place by holding
a piece of polished steel at an angle against the mouth of the setting.
Then the set stone is cut off and soldered in place on the work. Just
don't quench it!
One can cut rotating tubing in a flex shaft chuck rather crudely by holding
a pair of snips or side cutters tightly onto it while it is rotating in
the flex shaft. This has the effect of "spinning" the tube inwards simultaneously
creating a bead with smoothly tapered ends. One can even close one end
off completely by first cutting the tube with snips to bevel them inwards
and then hold a piece of steel against the rotating tube end to close
it. As mentioned before round nosed pliers work well. This has applications
when making stick pin ends. There are also professional (and professionally priced) specially hardened
steel angle cutting jigs available for cutting wire, tubing and sheet
at specific angles. One saws against the tool itself to obtain exact angles.
Frei and Borel carry them in North America, Fischer amongst others in