Just a side note. A piece this large without holes once finished
could be deformed in the heat of the sun on a hot day, dependent on
the wall thickness of the material of course.
Does this ever happen in practice? I would have expected that a
hermetically sealed piece to be very hot at the point in time that
it was sealed, so after it cooled it would contain relatively low
pressure air even on hot days. Or does gas slowly diffuse through
solder joints and imperfections in the metal?
Kit
Hi Janet,
First you say,
The air issue arises the moment a shape closes e.g., some shapes on the tube are likely to seal before others even if you are soldering them on all in the same heating, which means you have to continue heating closed forms (in order to close the unclosed forms). Obviously the issue arises even more seriously if you solder each of the five shapes on separately, or if the complex object will later be heated again for other additional solderings.
I could not/would not solder closed forms to something else.
Then you say:
The holes will be in the parts of the tube which are covered by the closed forms (to allow the air in the closed forms to escape via the tube), so they won't show anyway. As I wrote in the initial post, the final 'closing' of the tube will be screwed in place i.e., no soldering.
If you do it this way, I assume you will be pickling the object,
possibly between solderings, and my suggestion, advice, experience
applies.
So I am confused as to how you are planning to do this. What I wrote
was comprehensive in case someone on this forum following this
thread who wants to try to solder forms closed and then do further
soldering would know how to do it from my experiences.
Good luck, let us know how it goes, wear goggles!
Richard Hart G.G.
Denver, Co.
Hi,
I do work with larger pieces on a regular basis. I don’t do closed
hollow forms often, but in my experience a 2 mm to 3 mm hole should
be fine. I am assuming you will be heating up the piece somewhat
slowly with one or maybe two large torches with bushy flames. I have
not had any distortion this way, providing you let the piece air cool
after soldering and don’t quench it in water.
Thanks,
Joost
Just a side note. A piece this large without holes once finished could be deformed in the heat of the sun on a hot day, dependent on the wall thickness of the material of course.
I had this happen earlier in my career when I was trying to be
fancy. The pieces were soldered shut and having gone through several
heating and cooling cycles, in and out of water during finishing, and
not showing any leaking or staining, I assumed there were
hermetically sealed. A couple of the pieces were left on the back
dash behind the rear seat of my car were I forgot about them for a
couple weeks. LA summer heat and they deformed slightly (twisted),
were as the other pieces that went into showcases didn’t. The pieces
were made of 18 gauge sterling. Exactly what caused the deformation
(cold instead of hot) would be open to speculation, but it was
triggered by temperature swings of about 40 degrees F.
Dan Culver
Fascinated to hear you use such large holes!!! Do you do this because you had problems with smaller ones? Or just to be safe?
Many years ago I produced thousands of belt buckles and the hole
size progressed larger in the earlier years to accommodate different
problems that cropped up, until troubles stopped at 2.5mm. The
larger holes have an added benefit of speeding cleaning and flushing.
In production your hole size will depend much upon how fast you heat
your pieces and that is what drove my hole sizes going to 2.5mm. Safe
is a bit subjective in this case too. Is safe never having a failure,
maybe 2 out of 25, or is 5 out of 10 acceptable? The discount/premium
cost between refining and mill product will affect your decision as
well. I don’t think there is one correct answer. For cleaning
purposes you need two holes minimum, or with one hole, a probe to
apply pressure water into the piece with adequate clearance for the
water to escape around the probe. I tried that and found it
inconvenient, so two hole large enough for zero failures and easy
cleaning was my choice.
Dan Culver
Hi Joost!
I do work with larger pieces on a regular basis. I don't do closed hollow forms often, but in my experience a 2 mm to 3 mm hole should be fine. I am assuming you will be heating up the piece somewhat slowly with one or maybe two large torches with bushy flames. I have not had any distortion this way, providing you let the piece air cool after soldering and don't quench it in water.
This example is relevant to my piece:
Imagine a cylinder 25 mm tall made of 0.5 mm sheet and closed on
both ends with 0.5 mm sheet. Put a 5 mm hole in each end and stick a
tube (open at both ends; 25 cm long; 5 mm external diameter with 0.5
mm wall) thru it. Solder the tube and the cylinder together. Of
course, before soldering, a hole must be made in the part of the
tube that will be enclosed by the cylinder.
Since the tube’s internal diameter is only 4 mm., my fear is that a
2 mm. hole would cut away an awful lot of the tube. Two such holes,
even more. Given that the actual piece will not be a 25 cm. long
tube but rather 25 cm.s of 5, 6, 7, and 8 mm. tubing soldered
together (by fitting the ends of one into the other), I wanted to
have that 25 cm. ‘composite rod’ with as much structural integrity
as possible. Thus, I would really prefer not to cut out two 2-or-3
mm. holes in a 5 mm. dia. tube within such a short space as only 2.5
cm. (the part that will be covered by the 25 mm. long cylinder).
Since I will be using a very large propane-only (!) torch with a
very bushy flame, my original feeling was that a two 1 mm. holes in
the tube covered by the cylinder should be sufficient. Now I’m
thinking one 2 mm. hole. Or maybe one 2 mm. hole and also one 1 mm.
hole.
Since there is an awful lot of soldered work on the cylinder, etc.,
AND the openings in the ends of the cylinder, etc., fit nice and
tight on their respective tubes, I am NOW thinking of ‘setting’ them
on the tube with a bead setting…:-)…The main advantage is that
I would not have to soften the tubing by soldering…:-)…And, of
course, I don’t have to worry about air holes at all…:-)…
Janet in Jerusalem