Looking for Burnout Oven suggestions


#1

I am planning on getting a form2 (have to buy a house first lol, luckily our old house sold and so we are in the process of looking for our new one) and doing lost wax casting.

I was helped shown the process by a local jeweler who mentioned that to burn out resins, you need to have good air supply in the burnout oven.

I found a small furnace that I think I can get to work and the makers seem to be really good and willing to either tell me how to customize it or customize it for me before I purchase, but I need to know how to ensure good air supply in the oven to let them know what I need done.

Any ideas? What I’ve seen before is a small hole in the back connected to a chminey for flute. A fan is at the bottom of the flute blowing air staight up. This creates a venturi effect, pulling air from the oven, which supplies new air from the non perfect seal at the door. But I don’t know how big to make the hole or how powerful of a fan I would need.


#2

I actually run my burnout oven (a small Paragon SC2) in an outdoor kitchen. That was fine, until one night the sprinkler went off in the middle of a burnout. It shut down the kiln, but it now works again.

As far as venting, that little kiln has a plug on the top, and I just leave that out for the entire burnout.

I do have a larger glass kiln, but I don’t want to use it for burnouts. The SC2 has gotten a lot of residue on the glass window on the past two burnouts. I’ll probably switch the door back to the solid door before I burn out my next flasks.

What size flasks are you planning to use? Small or large? Are you using a vacuum casting unit or centrifugal?


#3

I’m mainly planning on doing small flasks. Rings, coin shaped stuff, maybe some bracelet accents or something.

I don’t have any of the tools yet, still picking them out and saving up to get them. But I plan on using a vacuum casting unit.

Here is my tentative planned list of tools:

Melting the metal - a DIY torch thing I was told you can get parts at Harbor Freight.
Vacuum investment and casting - Rio Grande - Out of Stock - https://www.riogrande.com/Product/RioVacuumTableforMoldMakingInvestingandCasting/705012

Oven - TableTop Furnace RapidFire - https://www.amazon.com/Rapidfire-Digital-Programmable-Controller-Beadmaking/dp/B00CUKD1UY/ref=lp_8129623011_1_1?srs=8129623011&ie=UTF8&qid=1485534558&sr=8-1

Printer - Form2


#4

The vacuum table looks like a good price, and if you’re only using the smaller non-perforated flasks, this unit will do exactly what you need. The system I have is similar but larger, with the section on the right able to accept larger perforated flasks, but I mostly it with the adapter for smaller 2x2.5" and 2.5x2.5" flasks. Something I didn’t have before was the ability to suck the bubbles out of the investment, so I really like the vacuum table for that. This is my unit, but I like the smaller size of the one you’re looking at…I think mine’s something like 90 lbs, and I’ve had a hard time finding a place to keep it. It’s also in the outdoor kitchen.

Also, add this to your list…if you use the 2.5" diameter flasks, you’ll want some of these flask extenders. They are thick, and make it much easier to invest your pieces. When the investment “boils” under the vacuum, it expands in size. These slide easily over the flasks, are thick enough to stand on their own, tall enough to prevent spills, and easily removed.
https://www.riogrande.com/Product/Rubber-Flask-Extender-2-12H-x-2-12-dia/702330

On the kiln, that looks like an interesting option at a great price. One thing I noticed…the coils are exposed on the inside. Since you are reaching into the kiln with metal tongs, and the inner chamber is small, you would need to be very careful and shut off the kiln before retrieving the flasks. I did notice that it has a similar controller to the Kerr Electro-Melt, which is a mini furnace for melting metal. However, my question would be if it’s programmable. The Electro-Melt is not. You can change the temperature, but if you’re burnout out flasks, you would have to babysit your kiln, and ramps are not as straightforward (the ramp schedules on the Formlabs castable resin will ramp up 200°F per hour or 325°F per hour…with the controller on the Electro-Melt, there’s no way to do that.

Another option to consider, but it comes at a higher price, is the Paragon SC3. The inner chamber is 7.75"x7.75" with a height of 8", and the coils are completely contained in the firebox, so no chance of touching them. It also has a fully-programmable controller with memory for four programs. Kilnfrog tends to have really good prices in general, and usually includes shipping. I have the smaller SC2, which actually survived being doused with water from our lawn sprinklers one night in the outdoor kitchen. I also use it for fusing small glass pieces, enameling, and precious metal clay. The RapidFire would also be able to do that.

I also know a woman who built her own burnout kiln with firebricks and a controller…

As far as your torch, you could even use the Bernzomatic MAPP torch from a home improvement store, which I think is $40. It has a nice bushy flame, and will get hotter than a propane or butane torch. I have this one, and also use it for torch enameling. http://www.homedepot.com/p/Bernzomatic-Premium-Torch-Head-328626/203718633

I used an acetylene/ambient air torch in the beginning (Smith Silver Smith or Handi-Heet Torch), but could not get larger quantities of metal hot enough. I switched to a dual-fuel acetylene/oxygen Smith Little Torch with a “bud tip,” but I had problems controlling the temperature of the metal, which caused porosity…but others use this technique just fine, so it’s likely “user error.” I recently upgraded to the Kerr Electro-Melt, which has precise control of the temperature, but it’s pricey (maybe $800 with a 5% coupon at Otto Frei). For what you’re doing, in the beginning, the MAPP torch should be fine. If you do look at a bigger torch, check Cyberweld. Their prices and service are the best I’ve found.

I wish that this kit was still offered…back in the 1980s, my parents gave me a casting kit. It literally cost $99, came with a small kiln, and a vacuum casting “box” that had a handle you’d pull to cast the metal. The casting grain was placed in the well in the top, then melted with a torch like the Bernzomatic…the heat from the flask helped get the metal liquified. Someone on a jewelry forum acquired one but didn’t know what to do with it, so I posted a PDF here of the instructions. www.katkramer.com/jewelcast

And one other thing…you might look up “steam casting.” If you wanted to play around with it, I’ve seen instructions online where they take a jelly jar lid, screw a handle onto it, and pack it with wet paper towels. After you remove the flask and melt the metal, you place the jelly jar lid on top of the flask, and the steam will force the metal into the mold. I know the technique is in this book: Lost-Wax Casting: Old, New, and Inexpensive Methods

Looks like you’ve done your research! Keep us all posted! :smiley: