Small burnout kiln

Jewelry Discussion
1

I have been lurking on this list for some time. I have examined the
archives for on burnout kilns. What I have found is OK,
but not complete enough for my needs. So, my first post. I need a
small burnout kiln to melt the wax from investments—something like
the Paragon SC11, I think. However, I can’t afford the $425 price
tag. I have James E. Sopcak’s “Handbook of Lost Wax or Investment
Casting” in which he describes how to make a small burnout kiln. I
have all the necessary components to build a kiln such as the one he
describes except for three items: 1)Nichrome coiled wire 660 watts @
110 Volts or 1000 watts @ 110 Volts, 2) a Pyrometer, and 3) suitable
power control (thermostat) 660 watts or 1000 watts. Do any of you know
where I might purchase these items? Regards,

Mike Youngblood

2

A ceramic supply house such as Amaco should have them. A mom and pop
greenware shop might be another possibility.

Marilyn Smith

3

A refrigeration ac heating supply house will have what you need to
build that little furnace. The element will be replacement one for a
clothes drier and the control is what s called an infinite control
for an electric stove element. These are available in 220 or 110.
The element use just involves a knowledge of ohms law E=IR an Power
in watts P=IE. A better bet on the control is a digital controller
but By the time you have bought a pyrometer or a controller you might
as well have bought a Paragon furnace!!! It is best to steam dewax
before using a kiln – you should check with paragon
about using these as a burnout kiln.

4

Hi there Mike, I made this kiln about three years ago. I’m not giving
you shop names because I live in Australia - they’re probably not over
in America, so you’ll have to make do with the generic type of store.
The nichrome wire I bought from a shop that repaired electrical
appliances. The pyrometer from an electronics shop although you can
get these from ceramics/pottery supply places but the only size
offered to me was bigger than the kiln itself. The power control I
use is a control to limit the rpm’s on a brush-cutter motor (like a
drill), also from an electronics shop - kit form. This doesn’t stop
the temperature from rising, merely slows it down. You can buy
thermostat controls for kilns (ordering tham as spare parts) but you’d
have to know what you were doing in the electronics department - they
don’t hook up directly to the wire.

Enjoy building you kiln
Eileen

5

Hi Mike,

1)Nichrome coiled wire 660 watts @ 110 Volts or 1000 watts @ 110
Volts, 2) a Pyrometer, and 3) suitable power control (thermostat)
660 watts or 1000 watts. Do any of you know where I might purchase
these items?

Look in your Yellow pages under ovens, thermostats etc. You might get
lucky & find someone that sells everything you need.

Here’s another idea you might try.

Get a one or two burner electric hot plate & clay flower pot (be sure
it’s clay & not one of the plastic ones) that’s wide enough at the
open end to just cover one of the elements in the hot plate. Place a
shallow pan that’ll fit in the pot or that the pot can sit in, on the
heating element. Place the flask to be fired in the shallow pan.
Support the flask on 3 equally spaced nails or some other metal
support. Wrap the flower pot in heavy duty aluminum foil & place the
inverted flower pot over the flask so it covers the heating element
entirely. Punch a hole in the foil where it covers the hole in what
used to be the bottom of the flower pot. Turn the hot plate on. Since
there’s no thermostat you’ll have to play temperature control by ear.

Dave

6

Years ago I built the burnout kiln described in Sopcak’s book. I
enjoy making tools as much as creating jewelry. It is even more
satisfying to me, to see if I can build something out of found
material. It’s a challenge to do it make something as cheaply as
possible and FREE sounds good to me. Since the materials called for
in this plan are very common, I was able to build the kiln without
buy anything. How much cheaper can you get. However, I did decide
that, rather than using a heating element from an old hot plate, I
would buy a new one, since that was the one item that would
deteriorate from use.

There was one major problem I encountered. I was so proud of how well
everything fit together, after carefully cutting the sheet metal and
bricks. There were no gaps anywhere (I only wish my joints in silver
were as tight). Once it was assembled, I decided to turn it on to
make sure everything was connected right. The result was that it got
so hot, in a short time, that the heating coils collapsed and shorted
out. The coils actually welded themselves together.

After carefully studying the plans again to figure out what I had
done wrong, I found on the last page, a reference to vent holes in the
back of the oven that could be used to put a thermocouple through.
Upon closer inspection of the photos, I did discover what appeared to
be two holes in the back of the oven. If my memory is right there was
no mention of making these event holes in the instructions.

I was not planning to buy a pyrometer at that time, so I had not paid
attention to the section on how to install it through vent holes. I
also had not installed the power control. I wanted to check to see if
everything was connected correctly first.

Since I have worked with kilns for many years, I should have known
better, but I suppose I just didn’t think the little oven would be
that efficient. With the tight joints that I created, the heat had no
where to go, so it just kept getting hotter and did it really quick.

I got busy with other things in my life after that and never went
back to correct the problems. Even though I had problems it
demonstrated that it had the potential to being a very usable, small,
and cheap kiln, if you vent it and use a controller.

Mike Wallace

7

I also have constructed the same kiln described in Sopcak’s book . I
utilized a high wattage, i.e. commercial grade light dimmer
controller to adjust temperature. And with a pyrometer have had
excellant results in controlling temperature. Very little variance in
maintaining the correct temperature once you determine and mark your
settings. Just and occasional look and or adjustment. Venting is very
important to preserve the element and clean burnout. burnout.

charles
@charles_hayes

8

Hi Mike,

  I have all the necessary components to build a kiln such as the
one he describes except for three items: 1)Nichrome coiled wire 660
watts @ 110 Volts or 1000 watts @ 110 Volts, 2) a Pyrometer, and 3)
suitable power control (thermostat) 660 watts or 1000 watts. Do any
of you know where I might purchase these items? Regards,

We can sell you the parts you need. We sell the wire straight and you
can coil it by wrapping it on a rod. How long do you need the coil to
be? The wire is sold in different gauges and so they have different
values. Is the element exposed or embedded? How is it going to be held
in place? Will you need ceramic plates for it? The pyrometer is $88.
Do you need a thermocouple with it? Are you just wanting a dial type
thermostat that has numbers 1 through 10 or something more
sophisticated that actually has temperatures? Such as a digital
control. The simple 1 to 10 control is $40.50 and the digital control
would be about $300 to $800 depending on what you want in it.

Let me know and we can supply you with what you need.

Ken Kotoski
MPG Repair
www.mpgrepair.com

9

Thanks for the reply Eileen, A number of you Orchidians have replied
to my inquiry about building a small burnout kiln. Thanks to you
all. It looks like I am on the right track. I have found a place on
the net that sells Nichrome wire. Of course, there are a number of
places were I can purchase a Pyrometer and thermocouple hook up and
an on/off controller. I’m still looking for good prices or “used”
“second hand” ( or to be politically correct, is it “preowned?”)
components for these items. Anyway, thanks all for the help. Regards,

Mike

10

Mike,

 If my memory is right there was no mention of making these event
holes in the instructions.

You are correct about this. I have the book right in front of me.
No mention of making holes for venting the oven. The holes for the
pyrometer and thermocouple would vent some heat but I doubt if that
is the real purpose. I suspect that the pyrometer and the thermostat
like on/off controller would normally regulate the heat in the kiln.
As with all kilns, it is a good idea to some test firing to get a
handle on the kilns efficiency. I am glad that you mentioned this
problem. I would probably have done the same thing. At any rate,
when I first fire up the kiln, I’m going to do it outside my shop and
read a book or something while I log the firing schedule. Thanks for
the tip. Mike

11

Thanks for the reply Ken. This is great. I think we can do
business. Let me see if I can give you the you need.

 How long do you need the coil to be? The wire is sold in different
gauges and so they have different values.

OK, I can’t be exact with this measurement but I can come fairly
close. The inside dimension of Sopcak’s kiln is 4" x 4" x 4-1/2."
Groves are routed in two of the side (soft insulating) firebrick to
house the Nichrome wire. These bricks are 4" x 4-1/2." The
“M"shaped grove in each side brick, linearly, is approximately 11.”
So I would need a minimum of 22" of Nichrome wire plus enough more
(maybe 5" per side or 10" ) to go through the back brick and connect
to the terminal board, maybe 33" total. This is the raw or initial
measurement; I will leave it up to you to figure out how much more
wire will be needed for coiling. I don’t have a clue as to what
gauge of wire I need. I speculate that the groves in the brick would
be about 1/4" in diameter if that helps.

 Is the element exposed or embedded? How is it going to be held in
place? Will you need ceramic plates for it?

As described above, the element is embedded into a grove or channel
cut in the soft fire brick. I have not thought about holding it in
place. Perhaps I could make some U-shaped staples from the Nichrome
wire and push these staples into the soft brick at appropriate
intervals to hold the coiled Nichrome wire in the grove. What do you
think? I don’t know what you are driving at with the ceramic plate
question. Maybe you could enlighten me. Perhaps I do need a ceramic
plate?

The pyrometer is $88.  Do you need a thermocouple with it?  Are you
just r something temperatures?

I can manage a pyrometer for $88 but I will need a thermocouple. The
idea is that the thermocouple protrudes through holes in the
firebrick and is attached to the pyrometer (at least, that is the way
I understand it). I guess I can manage with the numbers 1 through 10
although I was thinking that the pyrometer would have degrees F on
it. I thought I saw a ceramic kiln pyrometer selling for about $80
with an F degree temperature scale??? If I just have numbers, how can
I calibrate the kiln? Will I need to get a portable pyrometer with a
degree F gauge and do some firing schedules to calibrate the 1
through 10 scale for degrees F? The maximum temperature I need to
reach with this kiln is 1900 F. It is critical for me to know the
temperature of the kiln at various stages in order to burn out the
wax but I can’t afford to pay $300 for a pyrometer with a F scale.

That is about it. If you need more let me know. Let me
know the amount of Nichrome wire you think I will need and the cost;
also the give me the price of the thermocouple and pyrometer and
approximate shipping cost UPS ground.

Regards,
Mike Youngblood

12

One more question before this kiln question dies. I am still a
jewelry “wanabee” maker assembling my tools and such. I bought a hand
made kiln that looks fairly good, white enamel outside and firebricks
inside. It is made to work on 220 current. Are the thermocouple
switches and on-off thingamajigs (oh! “apparatus” to you folks
overseas) that are easy to get for this size current? I assume that
the 110 ones would not work for 220?

Thank you,
Rose Alene McArthur
@O_B_McArthurs

13

Hi Mike, Okay great. Now does the element need to be in one piece or
two? The length and the wattage will determine the gauge. If you need
two are they each 33" or a total of 33" for both? Also is the 33"
measurment the length of the groove? If so the coil will need to be
shorter. This is so you can stretch it out a little. The coils can’t
touch each other or they will short and create a hot spot that will
prematurely shorten the life of the element. As for the lead ends,
however long you want them is fine. If they are too long you can just
cut them off to the right lenght and use the extra for your U clips.
The connectors you use on the element ends will need to be for high
heat. They need to be stainless steel or nickle plated. If you don’t
have these we can supply them as well. The best setup would be some SS
screws and nuts. This makes for easy element changing if ever needed.
Any insulators needed on the element wire for the connectoins should
be ceramic. If you are using a metal cabinet ceramic insulators should
also be used to prevent a short from the cabinet to the elements.

Fire brick will hold the wire fairly well but as the wire gets hot it
will become ‘soft’, not so it will melt, unless it gets to it’s
melting temp., but so it will sag if not held in the groves. So using
some of the Nichrome wire for U clips is what is normally done in
firebrick ovens.

The ceramic plates are used in some ovens to hold the elements but
since you have groves in your firebrick you won’t need them.

The Pyrometer is in degrees F. But you will need a thermocouple with
it to make it work. A thermocouple is $34.50 and will include hookup
wire. We will calibrate the pyrometer to whatever temp you will be
needing. A note about analog pyrometers: They are accurate at the
calibrated temp. They are not accurate at any other temp. So if you
need it to be accurate at say 1300 degrees F then at 200 degrees F if
would be off by an amount, generally 20 to 50 degrees F but could be
more, so as the temp moves closer to 1300 it would get more accurate.
After it passes 1300 it would start to loss accuracy again. This is
true for all analog pyrometers. Analog pyrometers are the type with a
needle. A digital pyrometer is accurate at any temp to within a degree
or two usually. They also are much more expensive.

The controller is the item that would have the 1 to 10 numbers on it.
The cost for one of these types of controls is $26.70. To start with
once you have the whole oven put together don’t crank the controll all
the way up. You should start in small increments and mark the 1 - 10
dial on the controller for different temps. That way you will have a
reference to gauge by when you need them.

For shipping I would need to know your zip. We charge actual
shipping.

Ken Kotoski
MPG Repair
www.mpgrepair.com

14

Hi Rose, Thermocouples are available you are probably using a type ‘K’
but could be different. The controll should be available or if the
exact match is not a suiable replacement is. Voltage is important as a
110V would not work for a 220V unit. However a unit rated for 220,
240, 250V would work for a 220V. If you needed to replace the controll
you would need the amp draw along with the voltage. Or if the control
has a make and model number on it that would work to cross it over.

Ken Kotoski
MPG Repair
www.mpgrepair.com