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 HERMES2069 |
Heating element | #21 | ||
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Posts: 481 01/27/2009 07:48 |
I use a double wall insulated flue
 , end caps, 10", with a Mica strip heater. I use an immersion thermostat to control it. simple and very accurate.
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 canerodscom |
#22 | |||
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Posts: 1960 01/27/2009 09:52 Bamboo preacher |
John, (BigTJ)
Though I would discourage no one from using a mica strip heating element, I have moved away from them. After I burned out my third mica strip I decided to build a heat gun oven. Once it reaches equilibrium, temperature from one end to the other varies no more than 6* F at 375 or so. For example, at far end the temp will be 377*, in the center 375*, and nearest the exiting air, 371*. Rather than post a tutorial on how my oven is built, let me just give some broad guidelines. The outer box is 4x8 duct inside 6x10 duct and sandwiching high temp insulation -- just as you see the mica strip heaters in rod making texts. Each end is capped. Through one end I inserted 5' or 3" dual walled furnace exhaust . Cut a hole for the heat gun in the same end. Heat gun is Black and Decker, less than $40 from either Lowe's or Home Depot.
The only drawback I have found is achieving steady temperatures at less than 160* F (heat set Urac). With a little effort, or perhaps a different heat gun, I can probably make that work too.
Harry Boyd
maker@canerods.com http://www.canerods.com http://www.canerods.blogspot.com http://www.bamboorodschool.com |
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BigTJ |
#23 | |||
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Posts: 703 01/27/2009 15:46 |
Harry,
Thanks, as usual, for taking the time to give me feedback. I was wondering, would a lightbulb retrofit work for your 160 degree set-up? A couple 100 or 150-w bulbs would probably get you there, you could mount them inside spare end-caps. BTW I insulated the heck out of my oven, I have a 3" duct inside a 6" duct inside a 17" by 17" wood box. The box is lined with tinfoil and stuffed with insulation, I put a whole roll of it in there. I followed the McAulty design (the one on your website) TO THE LETTER save the dimensions of the wood box are a little bigger. The only thing I can think may be wrong is that I somehow have some short-circuiting in the airflow, or not enough air flow going through, however I can feel a strong flow of air a the nipple. One day I might pull the oven apart and try to seal off where the nippile contacts the 3" inner duct. For now though it bakes awesome, so who cares if I have a temperature delta? Thanks, -John
Last Edited By: BigTJ 01/27/2009 15:53.
Edited 3 times.
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canerodscom |
#24 | |||
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Posts: 1962 01/27/2009 16:20 Bamboo preacher |
John,
The light bulb dealie might work. Thanks, I'll give that some thought. Managed to get it set at about 165* and held that steady for an hour. That worked plenty well to heat set the Urac. Harry
Harry Boyd
maker@canerods.com http://www.canerods.com http://www.canerods.blogspot.com http://www.bamboorodschool.com |
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HERMES2069 |
Safety | #25 | ||
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Posts: 482 01/27/2009 16:23 |
I hope you guys out there are building these ovens with safety in mind.
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canerodscom |
#26 | |||
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Posts: 1963 01/27/2009 18:27 Bamboo preacher |
Good point Phil. My oven stays cool to the touch on the exterior. The heat gun is connected to an outlet all alone on a 20 amp breaker. Fire extinguisher is 12
feet away and on the way out the door.
Harry
Harry Boyd
maker@canerods.com http://www.canerods.com http://www.canerods.blogspot.com http://www.bamboorodschool.com |
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BigTJ |
#27 | |||
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Posts: 704 01/27/2009 18:44 |
Ditto. These ovens are really safe though. much safer than say a home fireplace or space heater. The exterior of my oven is close to outside ambient
temperature, the inlet and outlet sides are made of sheet metal which can't catch fire.
That all being said, I have a fire extinguisher at the ready, run it outside, and never, ever leave it unattended. -John |
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glassfisher |
#28 | |||
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Posts: 16 01/29/2009 23:17 |
franklin wrote:Sorry for the late reply, it was a little over $100 for the element, cntroller and a few feet of high temp wire. |
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