On Thu, 22 Mar 2012 00:14:53 -0400, "Steve W."
wrote:
Ed Huntress wrote:
On Wed, 21 Mar 2012 22:45:39 -0400, "Steve W."
wrote:
Ed Huntress wrote:
On Tue, 20 Mar 2012 16:50:11 -0400, "Steve W."
wrote:
Ed Huntress wrote:
I use the oddball stuff for items where the strength isn't a real issue,
Decorative stuff or covers and such.
The high silicon gets used for wear related items. I like using it for
castings that will end up handling abrasive abuse or in locations where
it will be the wear surface. Yes it can be a real PIA to machine but it
wears real well once finished.
It makes REALLY nice bullet molds.
I use various molds, sand, metal, lost wax/plaster. Two home built
furnaces. One is electric and one gas. The electric is NICE for temp
control and even heating. The gas is much faster to full heat but hard
on alloys.
I'd like to get into it some more, and I'm half-equipped, thanks to
the generosity of onr of our regulars here. Now I have to build a
furnace. I built one of those little Gingery charcoal furnaces around
20 years ago, and it was enough to get me interested, but it
deteriorated and I haven't replaced it yet with something better.
Soon...
I started with a charcoal unit. They work BUT the temperature control is
REALLY difficult to do with repeatable results.
The gas units work pretty well IF you have a source of low priced gas to
feed them. These days that can be difficult if you don't have a NG line
already.
This was the basic idea I used for my electric.
http://www.dansworkshop.com/2008/03/...ing-furnace-2/
Mine is larger than this and has better temperature controls (from an
industrial oven with three temperature sensors)
From a cold start I can have a batch ready to pour in about an 1.5
hours. The batches after that take about 30-45 minutes after loading.
The gas unit takes about 45 minutes from a cold start and 20 or so for
each additional batch. But you don't have the thermal control over the melt.
I'd like to see one run. Did you use Kastolite, or what?
First one I used a home mix: 1 1/2 parts Portland cement, 2 parts
silica sand, 1 3/4 parts perlite and 2 parts fine fireclay Has held up
very well so far.
The newer one uses Mincast and firebrick.
If I do another it will be the home mix again, easier, cheaper and it
seems to hold up better.
I built the new one with a double wall as well. If you look at dans unit
just add a second housing with simple fiberglass insulation around it
inside a stainless cover. It reduced the radiated heat a LOT...
What's your opinion on this, Steve: Gas or electric? I won't do a lot
of melting. It will be pretty basic stuff. I can handle the electicals
or a gas burner. I have natural gas but I'm not in a hurry for melts,
so I don't care about that.
Hands down the electric. No dealing with gas plumbing or possible
leaks, no cleaning of jets or playing with the air mix to get it right,
no worries about what/if the gas is an odd mix that might add something
to the blend, MUCH more portable due to easier power access, and it is
MUCH, MUCH quieter than gas. Most of the gas units sound like let
engines which gets old really quick. With the electric you hear the
click of the contactors and the occasional sound of shifting metal in
the crucible.
What's the voltage and current draw on those things?
220-240 volts
My small electric has an inrush of around 18 amps on initial start and
that drops to about 15 once it is warmed up.
The big one takes about 40 on initial start and drops to 32-34 once warm.
Which do you think is easier to build?
Electric. BUT getting the room for the coil can be interesting. The
new one was easier sinse I knew what to expect. I used a sonotube
section with a thin sheet of foil around it. Then a coil of 1/2" black
poly around that secured with hot glue.
Thanks for your thoughts. I do know about the many online sources of
info, which I'll wade through when I'm ready for this. But since you
have both electric and gas, I'd really like your opinion.
Ok, that's one is archived. Thanks very much.
I have one of Gingery's old books about building an electric furnace
around here somewhere. It may have been written by his son. I gather
that things have progressed beyond that for home foundries, yes?
That all depends on how far you want to go, and how much you want to spend..
The Gingery furnace works but it isn't really easy to control if built
by the book. Most of the current designs use better controls and
materials. This allows a better pour because you can get a nice even
high temperature in the melt.
The big thing these days is that many more people have access to
information and sharing same. It really helps out when you can see what
works and what doesn't.
You can say that again. So many specialized and arcane interests...and
we seem to be able to find someone just as off-the-wall as we are.
Even dozens of them, with real experience and knowledge that just
isn't recorded anywhere else.
Someone posted a link to a boat plan yesterday, with a box keel and a
tunnel, which is based on the Sea Bright Skiff keel design. Being a
Sea Bright Skiff fanatic, I was tempted to jump in -- but I restrained
myself. It wasn't easy...
--
Ed Huntress