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Where is the hotest spot of a flame


#1

I have a vacuum casting machine and I’m about to cast my first piece
with it. I’m using Oxy/propane and a small Victor torch with a #4
propane tip. I’m used to using acetylene with the nice sharp flame.
But it seems that the propane flame is loooong and all blue. Where
is the hotest spot in such a flame? Can you cast with such a long
flame (at least10 inches) or am I doing something wrong? Tim
McCreight says to use a reducing flame, and that is what I’ve got,
but it is so long, I don’t know where to put it on the crucible. Any
advice would be appreciated.

Larry Heyda


#2

Get a rose bud tip for shorter flame and much more heat. The hottest
place is at the tip of the inner blue flame.

John Dach


#3

Wrong torch, wrong tip, wrong approach, talk with a qualified
Jeweller that is a certified or a knowledgeable person that can help
you so you don’t end up a statistic.

Stephen Wyrick, CMBJ
Gemmologist


#4

Hi Stephen,

Wrong torch, wrong tip, wrong approach, talk with a qualified
Jeweller that is a certified or a knowledgeable person that can
help you so you don't end up a statistic. 

Thanks for the triple condemnation. Makes me afraid to ask any more
questions on Orchid. I thought I was approaching “qualified,
certified, knowledgeable jewelers” by posing my question here. Is
everyone who joins Orchid a thoroughly educated professional trained
at a certified jewelry school? It seems many members are coming from
different fields but are trying to learn how to be jewelers by
reading, hearing from others, etc. Not everyone has the wherewithall
to attend an expensive jewelry school. As for your “wrong torch,
wrong tip, wrong approach” claim, I’m not sure you are completely
correct either. The Rio Grande catalogue shows a melting torch for
platinum that can be used for gold that has a single orifice tip. I
have heard that a rosebud tip is better, and I will get one, but I’m
sure there are others on this list who cast with a single orifice
tip. One very knowleadeable contributor here uses a cheap Chinese
cutting torch to do all his melting. So there are apparently many
approaches. Anyway, I thought your response was very unhelpful, and
I hope I’ll receive assistance from others on this list as I try to
learn this intricate craft.

Larry Heyda


#5

What is the problem is a single orifice tip can and will melt the
metal, it is just that if you are trying to melt a lot of material,
you cannot get enough Btu’s out of it, you cannot put enough gas
through it. A cutting torch or a rose bud tip has more orifices or
many more orifices thus you can get more Btu’s to get the larger
amount of material hot and melted. A very small mini torch tip can
solder gold wire inside of a cigarette paper without lighting the
paper on fire because the VERY small flame has the heat concentrated
in a very tiny area. Not much Btu’s but what is there is very
concentrated. To melt a large amount of material, you need much more
Btu’s thus a tip with more holes, burning more gas in a given time
period, thus enabling you to melt a quantity of material. Lastly,
the thing here is not really the temperature of the flame, it is the
need of greater Btu’s. If you thing of a gas stove burner, any one of
the individual flames is as hot as any other one. If you have just
one individual flame burning and try to heat a pan of water, you will
never get the water to boil. The heat loss from the pan and the
water is greater than the heat you can add to the pan of water with
just one flame. Now have all of the flames on the burner lit, each
being as hot as the next, but you have many flames. Now you can put
more heat (Btu’s) into the pot of water faster than the heat is lost
from the pot, and you can get the pot to boil.

I hope this helps you. I too was a bit short in my original answer
to your question. If you need more help on this, please feel free to
e mail me privately or call me (360.681.4240). I am located in
Washington State in Sequim on the Olympic Penn.

John Dach


#6

Larry,

Sorry for the wrong, wrong, wrong approach message. Please don’t
give up on orchid. Orchidians run the gamut from high school
students, to the finest professionals. Keep reading the posts and you
will discover a world of helpful suggestions and a good number of
members who will show great kindness as they share

Hang in there.

Mary A.
www.jewelryforthejourney.com


#7

Hi John,

Thanks much for your explanation about multi-orifice torches. I
never thought about it that way, but it makes perfect sense.

I have now successfully melted a good quantity of bronze with a big
old Craftsman cutting torch I bought at a farm auction last week. I
think I’m getting the hang of it. The other problem I had was not
understanding what a “reducing” flame really looked like. Once I
researched that on the net, and better understood the differences
between a neutral flame and a reducing flame, I was able to get a lot
of firepower out of the cutting torch, and the melting happened
quickly. I’ve also ordered a multi-orifice tip for my smaller Victor
torch. We’ll see which is better in the long run. Thanks again for
your help.

Larry


#8

Why thank you, Mary! How kind and supportive. I wasn’t seriously
going to quit Orchid. It’s a real lifeline. Others have already
helped me immensely, and I’m well on my way to successful casting
becuse of their generosity. I think this is a wonderful group.

Larry


#9

Hi Larry,

Is everyone who joins Orchid a thoroughly educated professional
trained at a certified jewelry school? 

No. You’re right in thinking that there are many people here on
Orchid who are from different fields. There are many “qualified,
certified, knowledgeable jewelers”, and there are people who do
beading, wire-wrapping, metal clay, polymer clay, those who take the
odd class now and then to add to their skills, and those like myself
who are self taught from reading books and participating in Orchid.

There should be plenty of people on here who are more than qualified
to answer your question but I think it’s one of those things where
people assume that you’ll get lots of answers and so they’ll let
others do the talking. I don’t have enough “big” torch experience to
be able to comment but hopefully you’ll get some better answers than
the negative one you received.

Don’t be afraid to ask questions on Orchid. Orchid is a very
friendly bunch of people even though sadly your negative feelings are
not the first I’ve heard. It’s very easy to be put off by one
off-hand (or seemingly off-hand) response and go away disillusioned.
The poster who responded may well not have had the intention of being
so dismissive and negative. Normally, you’ll find that people on
Orchid respond in a very friendly and helpful manner. Please keep
posting.

BTW, your sculptures are amazing! If your jewellery skills become
anywhere near as good as your sculpting skills, we’re in for a
treat.

Helen
UK
http://www.hillsgems.co.uk


#10

Hi Larry:

I use an old cutting torch to melt with at home as well. (I use an
oxy-hydrogen rosebud at school, but that rig’s pretty freaky to get
used to. Picture trying to adjust a reducing flame…when it’s
invisible…)

I suspect you’ll like the cutting torch better than a small rosebud
in the long run. Largely because it’s larger. Rosebuds, especially
small ones, are prone to flashbacks when they overheat due to
prolonged use. Cutting heads are so much larger that it takes a
lot more time to heat them up. So they’re a lot nicer to use. If
you’ve got one of the cutting heads where the cutting O2 handle flips
up to lay along the top of the torch, flip it up and wire it in
place, so there’s no way you can accidentally hit the cutting jet
while you’re melting. The results would be…spectacular. Otherwise,
wedge a block or something under the handle. You really don’t want
to hit that cutting jet with a couple of ounces of molten silver in
front of it.

Regards,
Brian Meek.


#11

Hi Brian,

Thanks for the confirmation about using a cutting torch. I also
talked with Richard Hart in Denver who has been using a big cutting
torch for the last 10 years, and loves it.

I’ve built a carriage that holds it in place over my crucible while
I’m pulling the flask out of the oven. Works well.

Larry.


#12

Thank you for the encouragement, Helen, and the kind words about my
sculptures. You might be very right that the response I got was not
meant to be ill-intentioned, but was just a stern warning to learn
the ropes before I went about playing with volatile gases. If that
was his intention, I apologize to him and everyone else for ranting
the way I did. Since then, a number of people on here have offered
me some good advice regarding casting torches, and I have found that
my huge Craftsman cutting torch does a swift job of melting a good
quantity of metal.

Your web site has a very sophisticated, classy look to it, and it
compliments your fine jewelry beautifully. I especially like the big
agate cab with the silver rail around it.

Thanks again.
Larry


#13

Hi Larry,

Thank YOU for your kind words about my website and jewellery. The
piece you like has been relegated to the depths of my jewellery box
as it’s one of the first pieces I made when I started making
jewellery about 18 months ago, so it’s got so many flaws. I have
lots of pieces I want to remake now that my skills have vastly
improved over what they were. My husband says I should keep them but
if I did that, they’d never be worn. I prefer to have pictorial
reference of what they were like and then pull them apart and remake
them - then take pictures of the improvement and actually wear the
piece. I’ve neglected my website for too long and am in the process
of getting some new pictures uploaded.

Thanks again.

Helen
http://www.hillsgems.co.uk


http://helensgems.ganoksin.com/blogs/