Paragon Kiln

Just a note on why two SSRs.

When you are using USA 220 voltage there are two hot lines. One SSR would indeed stop the current flow, but it won't de-energize the coils. Even though the coils would stop glowing, and the door interlock was open, anyone who touched the coils with a knife or tongs taking a blade out would be shocked ... or electrocuted.
Two SSRs disconnects the power from both ends of the coils. This is the only way a door interlock would be of any good on a USA 220 volt oven.

On the cost factor, I am with JT.
Yes, you can use the cheapest SSRs, TCs, kanthal, PID, etc. but you are building a piece of precision equipment. Just like in cooking - the better the quality of the ingredients, the better the quality of the dish.
You are unlikely to get an good quality 8 gauge type K TC for $10. Then you need TC wire, a TC connector block, etc. That is a lot more than $12.
I also would get a better PID than a $20-65 unit for a HT oven.
The coils are the engine of the oven, and the wire size and quality should be the best.
I would say a person with knowledge of HT ovens and good shop skills in metal work and welding could build a good unit for $500. A person who isn't as well skilled may not be able to build one at all.
 
So the doubled use of the SSRs makes sense now. I just put a rocker on the other hot, I hadn't thought to run the SSRs in parallel. I think I will do this. Thanks. One less thing I can screw up.

There are a bunch of insulated 3.2mm (8 AWG) wire diameter k-type TCs on ebay for under $10 I bought a couple and tested. Accurate to limits of my ability to test with a cone. Unless you are referring to the block that connects the extension wire to the TC wire (which was part of the TCs I bought), I connected the TC extension directly to the PID. I forgot to include the TC extension wire, which I think I used about 1 yard of, so call that $1.5.

I won't argue about PID quality. I bought one from Auber instruments, I think I paid $65, and while the control quality seems spot on, the interface is not my favorite. I looked for something wifi enabled or similar but didn't really find anything that looked like it had a better interface and wasn't proprietary (in other words, I could find replacement controllers from paragon etc, but couldn't find a good wiring diagram and wasn't sure if I was gonna be able to wire them/set them up with non-paragon systems. Do these controllers come with wiring diagrams and do they allow full user adjustment and auto PID calibration?

I used ~40' of 16AWG kanthal A1 for the resistance element. If I had used a larger gauge wire, I wouldn't have been able to maintain the recommended coil spacing to achieve my required resistance in the room I had. Not sure if guys are running 14 or 12 ga kanthal but as I remember, I would have needed about 75' of 14 ga and 120' of 12ga for a similar resistance, and both of those lengths could not be stretched by a minimum factor of 3 in the space allotted without going up to a coil OD in the 1" range. I didn't do this because I didn't want to mill out that much IFB for one and because many of the high dollar kilns I looked at weren't using those gauges or those coil diameters.

I agree that if you don't have any of the required tools or know how to use them that this would be a tough project.
 
Haven't made it to the end, but that build looks awesome. I may upgrade to that TAP controller in the future. I was worried when I looked that All I found looked to be specific upgrade controllers for individual kiln models. I thought that perhaps they had settings hard set from the MFR. Thanks for the info, I will read through the rest this evening.

The WIFI feature is particularly intriguing.
 
JAM said:
Hey, can I be your friend? :) I could use an oven for around $300.
Click to expand...
I've made one oven recently, that was for me. I have made a number of forges recently. I would send any business on that front to one of the dudes on the forum here who sells their stuff. I don't.
 
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