Recommendation? diy heat oven

Unfortunately unless I'm running off of my portable generator, 220 is out of the question because of Shop location
 
Hubert S. said:
Ok, just want to add one more thing regarding safety. If you design the furnace for a 20 Amp outlet, use the proper plug so it cannot be plugged into a standard 15 Amp outlet. The designation for the plug is NEMA 5-20P.
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Safety first! Always. It can never be said enough
 
So you have 16 Ga Kanthal (A1?) and you need to maximize the power available from 110V? At present, your 16 Ga Kanthal is in the form of (a?) 20-Ohm coil(s?).

Caveat: I am in the UK, so US mains supplies and wiring practices are a mystery to me.

If you have a 15A supply available, V = IR, R= V/I = 110V/15A = 7.33 Ohms.

You can cut down your elements to give around 8 Ohms.

Watts = Volts x Amps = 110 x 15 = 1650 Watts.

If you have 20A available, V =I x R, R= V/I = 110V/20A = 5.5 Ohms

You can cut down your elements to give around 6 Ohms

Watts = Volts x Amps = 110 x 20 = 2200 Watts

If you have 2 outlets, each of 15A, and able to be run at the same time, you could use one to run the PID controller and an 8 Ohm element on one side of the oven, and use the other to run the 8 Ohm element on the other side of the oven (the SSR feeding this element would be triggered by the pulsed DC output from the PID controller. Most provide enough output to trigger 2 SSRs in parallel), giving a total of 3300 Watts. I have done something very similar here in the UK with 2 x 13A 230V domestic power outlets running a 42" HT oven. For that, the heating coils were 3 kW per side.

Note that 16 Ga Kanthal A1 is pretty thin. I used it for the first half-dozen HT ovens I built, but had a few elements burn out and went up to 1.6mm (about 14 AWG) Kanthal A1 for the last 3 ovens. These have not, to the best of my knowledge, had an element failure and are coming up to 5 years old. I'd generally regard the 16 Ga as ok for occasional hobby use up to Stainless Steel temperatures, or for more regular hobby use to Carbon Steel temperatures. 14 AWG seems reasonably ok for regular use to stainless steel temperatures. Make sure element replacement is something you've considered in the design. My first ovens used a welded angle-iron frame and changing elements was a grinder-and-welder job. Later ones bolted together, a hard lesson learned.
 
timgunn1962 said:
So you have 16 Ga Kanthal (A1?) and you need to maximize the power available from 110V? At present, your 16 Ga Kanthal is in the form of (a?) 20-Ohm coil(s?).

Caveat: I am in the UK, so US mains supplies and wiring practices are a mystery to me.

If you have a 15A supply available, V = IR, R= V/I = 110V/15A = 7.33 Ohms.

You can cut down your elements to give around 8 Ohms.

Watts = Volts x Amps = 110 x 15 = 1650 Watts.

If you have 20A available, V =I x R, R= V/I = 110V/20A = 5.5 Ohms

You can cut down your elements to give around 6 Ohms

Watts = Volts x Amps = 110 x 20 = 2200 Watts

If you have 2 outlets, each of 15A, and able to be run at the same time, you could use one to run the PID controller and an 8 Ohm element on one side of the oven, and use the other to run the 8 Ohm element on the other side of the oven (the SSR feeding this element would be triggered by the pulsed DC output from the PID controller. Most provide enough output to trigger 2 SSRs in parallel), giving a total of 3300 Watts. I have done something very similar here in the UK with 2 x 13A 230V domestic power outlets running a 42" HT oven. For that, the heating coils were 3 kW per side.

Note that 16 Ga Kanthal A1 is pretty thin. I used it for the first half-dozen HT ovens I built, but had a few elements burn out and went up to 1.6mm (about 14 AWG) Kanthal A1 for the last 3 ovens. These have not, to the best of my knowledge, had an element failure and are coming up to 5 years old. I'd generally regard the 16 Ga as ok for occasional hobby use up to Stainless Steel temperatures, or for more regular hobby use to Carbon Steel temperatures. 14 AWG seems reasonably ok for regular use to stainless steel temperatures. Make sure element replacement is something you've considered in the design. My first ovens used a welded angle-iron frame and changing elements was a grinder-and-welder job. Later ones bolted together, a hard lesson learned.
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Wow, you guys are really really smart and really really fast at replying!
 
I was able to get my homemade oven up to 1796°F however the ceramic terminal block in between the high temp cable and the element now has melted lead in the terminal block. any suggestions it's a 30 amp rating and I'm using 120 VAC?
 
prodago said:
I was able to get my homemade oven up to 1796°F however the ceramic terminal block in between the high temp cable and the element now has melted lead in the terminal block. any suggestions it's a 30 amp rating and I'm using 120 VAC?
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Picture ?
Did you twisted Kanthal wire from elements on ends ?

pnVMKgm.jpg
 
prodago said:
No I did not, I'm assuming I should have? I tried uploading a pig but it's telling me I need a URL which I don't have
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online instructions often refer to twisting the end wires (where you have doubled back the long end wire to produce the twisted section, or better yet twisting AND bending 180 degrees and doubling over at the contact point to reduce the resistance (and thus heating) at that point. You want the wire heating inside the oven (single strand), but NOT to heat at the connector block (you do this by NOT having a single strand attached to the connector. You really can not have "too many" parallel strands there - you just need the bundle to be small enough to fit into the connector.
 
Cushing H. said:
online instructions often refer to twisting the end wires (where you have doubled back the long end wire to produce the twisted section, or better yet twisting AND bending 180 degrees and doubling over at the contact point to reduce the resistance (and thus heating) at that point. You want the wire heating inside the oven (single strand), but NOT to heat at the connector block (you do this by NOT having a single strand attached to the connector. You really can not have "too many" parallel strands there - you just need the bundle to be small enough to fit into the connector.
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Thanks Cushing
 
prodago said:
No I did not, I'm assuming I should have? I tried uploading a pig but it's telling me I need a URL which I don't have
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You can use Imgur for picture. I hope that ceramic terminal block is outside hot zone not inside chamber? I mean Kanthal wire goes thru the bricks out and then on ceramic terminal block , right ?
 
The terminal block should be a high temperature ceramic block with stainless steel metal parts. Brass screws are 360 brass, which melts at 1700F/950C.
 
sorry for all of the newbie questions but is it possible to connect two coils together for one coil? Or would this not work?
 
prodago said:
sorry for all of the newbie questions but is it possible to connect two coils together for one coil? Or would this not work?
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Find someone who know more then you about this . You can connect two coils together of course , but how they are connected make huge difference ......
Consider a very simple circuit consisting of four light bulbs and a 12-volt automotive battery. If a wire joins the battery to one bulb, to the next bulb, to the next bulb, to the next bulb, then back to the battery in one continuous loop, the bulbs are said to be in series. If each bulb is wired to the battery in a separate loop, the bulbs are said to be in parallel. If the four light bulbs are connected in series, the same current flows through all of them and the voltage drop is 3-volts across each bulb, which may not be sufficient to make them glow. If the light bulbs are connected in parallel, the currents through the light bulbs combine to form the current in the battery, while the voltage drop is 12-volts across each bulb and they all glow.

In a series circuit, every device must function for the circuit to be complete. If one bulb burns out in a series circuit, the entire circuit is broken. In parallel circuits, each light bulb has its own circuit, so all but one light could be burned out, and the last one will still function.
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prodago said:
sorry for all of the newbie questions but is it possible to connect two coils together for one coil? Or would this not work?
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I am decidedly not expert at this ... but i would try to stay away from connecting two coils together ... i would not count ontwisting them together to maintain the connection, solder would instantly melt, and any kind of "connector block" would likely fail due to the temperatures it would be exposed to.

Raw kanthal wire is pretty inexpensive, and it does not appear to be hard at all to wind your own coils ... i would just go the route of making your own if you need a longer coil...
 
I agree with Cushing that making a proper coil is pretty easy. I disagree that connecting two coils in either series or parallel is bad. If one coil is connected to a proper stainless and ceramic terminal block, two will connect just as easily.

Use connector block like this:
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2pcs 30A Ceramics Terminal Blocks High Temp Porcelain Ceramic Connectors 2 Way | eBay

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For series, connect the coil to opposite sides of the same terminal. For parallel connect each coil to a separate terminal and jumper/double the power wire to both coil leads.
s-l1600.jpg
 
Stacy ... i am thinking such connector blocks need to be on the outside of the oven? If so, i was merely thinking it best to avoid creating additional holes in the walls just to get the things in series. If parallel wiring is wanted, such connector can not be avoided.

If the connectors can reliably be placed inside the oven, then i am surprised....
 
Cushing H. said:
Stacy ... i am thinking such connector blocks need to be on the outside of the oven? If so, i was merely thinking it best to avoid creating additional holes in the walls just to get the things in series. If parallel wiring is wanted, such connector can not be avoided.

If the connectors can reliably be placed inside the oven, then i am surprised....
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In mine tube furnace they are inside and they hold just fine .1250 Celsius is maximum temperature I used in that oven for sanmai .
PS . Connection can be done with Tig or spot welding , no need for connectors .BUT as you mentioned making new one would be my choice
KAfT661.jpg

m4grTVC.jpg
 
Natlek said:
In mine tube furnace they are inside and they hold just fine .1250 Celsius is maximum temperature I used in that oven for sanmai .
PS . Connection can be done with Tig or spot welding , no need for connectors .BUT as you mentioned making new one would be my choice
KAfT661.jpg

m4grTVC.jpg
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Huh, I’m surprised that the high heat does not both weaken the screws, and also accelerate the formation of oxides on those screws. But… if it works, it works
 
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