Oven and Others

[Hawkeye]

Last Saturday, my buddy Frank and I took a little field trip to pick up some equipment from a guy named Evan (Meister on another forum) who had to close his shop. A one-day trip, about 10 hours driving round trip on 2 hours sleep. Frank had already made one trip and picked up a sweet little horizontal mill and a gearhead drill press.

It was an absolute pleasure getting to know Evan. His interests follow a wide variety of directions and he has allowed his imagination to express itself in many different projects. One of these was a heat treating oven he built about five years ago. This was the reason for the trip on Saturday. The controller allows the oven to maintain temperatures within 5 degrees, with a top temperature in the area of 2000 degrees. The cavity is around 13"x8"x4", big enough for pretty much any project I could imagine.
   

   

   

I also picked up a large shelf unit (2'x4'x6') that will be a big help in setting up my new shop, a small drill press for my wood shop, a bin full of good drill bits and a large ammo box with the whole bottom covered in Boeing drill bits. And, as a bonus, about 9 square feet of 1/4" polycarbonate.
   

   

   

[PixMan]

What a great haul! I'd LOVE to have such a furnace. Is that 2000º in F or C? I don't know if 2000ºF is hot enough for heat treating tools steels, but I believe so. Not quite hot enough for melting it though, right?

I have two of those 4 foot deep shelving units, a 6 foot long one and an eight foot one. They are an amazing collector of junk with those acres of flat surface!

Got drills? Wow, that's a lot of sorting ahead of you. I like a bargain, but if it's like the set of reamers my dad had picked up a few years ago there's a lot in the same size range and not enough variety for the space they occupy. I hope you did better.

[PixMan]

BTW, I know of the gentleman Evan from another machining forum and his health problems that are worsening and leading him to downsizing his shop. If his "on-line personality" is any indication of how he is in person he's a really good fellow and so gracious in offering his tools and equipment for a song. I know from his skill level that your new furnace is no hack job!

I wish I could travel out to meet him before he becomes worse.

[Hawkeye]

Ken, you've read Evan correctly from his posts. Definitely a man worth knowing.

[Hawkeye]

I finally got the oven running today. I couldn't get Evan's controller to work so I ordered a PID unit from eBay. I had that working, but realized that I had the two elements connected in series. (Comes from the lag between ordering and receiving the PID) When I connected the elements in parallel (9.4 ohms - 25.5 amps @ 240 volts, over 6000 watts), the 40 amp solid state relay blew. This week, I bought a 50 amp SSR at the local electronic supplier. It does a nice job, working with the PID.
   

The process of setting up the PID controller included making a large aluminum heat sink ...
   
   

The attached SSR is the one that blew.
   

I built an aluminum enclosure to fit.
   
   

Here's the oven mounted on the stand that used to carry my ZX-25 mill/drill. The small display is a thermocouple gauge that I was going to use for the oven I was building before the fire. It reads in Fahrenheit, while the controller reads in Celsius. I thought it would be useful to see both at once. Unfortunately, the small one reads a LOT higher than the controller. As the saying goes, "A man with a clock knows what time it is. A man with a hundred clocks is never quite sure." I'll have to find a way to calibrate the whole affair somehow.
   

[Highpower]

6000 + Watts!!!???  

I'll bet it doesn't take long to warm up!

Mike, on the SSR that blew - if you look closely at the right lower corner of the label, is it a square 90° or is the corner cut off at a 45° angle?  Just curious.

p.s.
Run the Autotune function and it will calibrate itself.

[Hawkeye]

All corners are square. I finally found AT on the 2-page manual. I'll run it tomorrow. Thanks.

[Highpower]

I originally bought a 40A SSR along with the PID controller I ordered for my furnace. It turned out to be a Fotek unit as well. But I kept finding all kinds of reports on the internet about a LOT of them blowing up and some starting fires. I decided not to use the Fotek and ordered a more expensive model made in the USA instead. From what I could gather there seem to be a lot of counterfeit SSR's being made in China using components that only have half of the capacity they the claim to be. An Underwriters Labs report shows that the fake units have all square corners on the label.

http://canada.ul.com/safetyalerts/ul-war...e-13pn-52/

I checked the one I have and it has the right lower corner cut off at a 45. So I was curious about yours since you mentioned it blew up on you. I'm collecting the parts to build a second (larger) oven myself, and Ed was kind enough to hook me up with another American made SSR. I still don't trust using the Fotek relay I've got, especially since the new oven will be a higher wattage. No where near your 6000 watts though Mike!

[Hawkeye]

I tried the auto-tune this morning. It wouldn't let me turn it on. Must be a flaw in the firmware.