Heat treat furnace

[TomG]

I have that very same furnace myself and have been meaning to convert it over to a PID controller. They are cheap and readily available from Light Object, and McMaster Carr carries the Type K thermocouples (which I have actually purchased). I used similar PID's on my anodizing setup and they worked quite well.

Tom

[Dr Stan]

(12-01-2015, 10:26 PM)Highpower Wrote: At least now I know it's "do-able". But being a typical lazy American I would want a controller that reads out in Fahrenheit so I know immediately what I'm looking at. Conversion chart? Ain't no body got time for dat!!!  

Start learning the metric system.  It's so much easier to use and is the system used by virtually all of the world, with the exception of the US and Liberia.  Actually manufacturing in the US switched over several years ago.  All engines are in liters, spirits are in milliliters, drugs are in milligrams, electrical/electronic values have been in the metric system from day one, and so on.

BTW, water boils @ 100 degrees C and freezes at 0 degrees C.  The mass of 1 liter of water is 1 kilogram, how much does a quart of water weigh?  For those of us who wish we could loose weight, 100 Kg sounds a lot better than 220 lbs.

Also buy the HT furnace as its a very good buy.

[Highpower]

(12-02-2015, 01:11 PM)PixMan Wrote: Feel free to call or text me anytime you might need a Cº to Fº conversion, I got the app for that on my phone.

Well Ken, if you can figure out a way to put that app on my ancient flip phone....
Yeah, I'm still in the dark ages.

[Highpower]

(12-02-2015, 03:15 PM)TomG Wrote: I have that very same furnace myself and have been meaning to convert it over to a PID controller. They are cheap and readily available from Light Object, and McMaster Carr carries the Type K thermocouples (which I have actually purchased). I used similar PID's on my anodizing setup and they worked quite well.

Tom

Tom, can you point me to a part number for the thermocouple? Until I actually get the furnace, I have no idea what's in it or what will fit.  

Light Object huh? Like this one?
http://www.lightobject.com/JLD614-Dual-D...-P552.aspx

Still don't know what amperage SSR relay I would need so I'll just have to wait.

[TomG]

Willie,

You'll need one of their High-Temperature Thermocouple Probes for Air. You'll have to figure out the length based on your furnace.

I think you'll also need some type K thermocouple wire to hook it up.

Here is some good info: The Basics of Thermocouples

Tom

[Highpower]

(12-02-2015, 03:15 PM)TomG Wrote: I have that very same furnace myself and have been meaning to convert it over to a PID controller. They are cheap and readily available from Light Object, and McMaster Carr carries the Type K thermocouples (which I have actually purchased).

Tom

Quote:You'll have to figure out the length based on your furnace.

Tom, I took that to mean that you have already purchased a thermocouple that fits the "very same furnace" and already knew the length needed?

Well, no matter. I'll be picking up the furnace in the morning anyway.

[TomG]

Willie,

The hole in the back of mine for the thermocouple didn't look like it was factory, so yours may not be the same. best you order the thermocouple based on what your furnace actually has. Seems like whenever I order something based on expected dimensions, it always ends up wrong.

Tom

[Hopefuldave]

I've seen PID controllers complete with the solid state relay for 10 - 20 or so Local Currency Units, all good but... ones with ramp / soak time functions seem to all be 80 or more LCU, anybody know of inexpensive ones? I'd like to be able to anneal / normalise etc. without having to fiddle every few minutes setting temperatures!

Dave H. (the other one)

[Highpower]

(12-04-2015, 01:35 PM)TomG Wrote: Seems like whenever I order something based on expected dimensions, it always ends up wrong.

Tom

Copy that!  

Well -- I picked up the furnace today. Good news / bad news..... but most of it GOOD.  

It's a pretty clean unit and slightly bigger than I thought. Inside dimensions are 4.5 x 4.5 x 6.5 inches so it's a little deeper than I was expecting. The whole thing stands nearly 15 inches tall. 240 volt, 6.3 amps input. I was a little surprised to see that it has a mirrored scale. (Not that it will be used.) Nice touch though. Makes me miss my old Simpson 260 VOM.  

Plugged it in and flipped the switch to see what would happen, and was rewarded with a nice pink glow around the interior walls.  

I didn't want to leave it on for very long though because of the bad news. The thermocouple is GONE! The only thing left was a short (1-3/4") piece of broken ceramic rod that used to house the thermocouple wire loop. The furnace only has a 1/4" diameter hole in the back of the case that goes straight into the interior chamber where the thermocouple belongs. So I have no idea of how it is supposed to be retained in the case, and absolutely no clue about how long it should be or how much is supposed to be sticking into the interior chamber.  

So for now, I've ordered a PID controller, a 40 amp SSR (solid state relay) for supplying power to the heating element(s), and a heat sink for the SSR. I'll probably be doing a lot of web surfing and head scratching trying to figure out what to do for a thermocouple and how to mount/seal it.  

But hey..... for 2 bills, I ain't complaining!      

   

   

   

   

   

[TomG]

It does look clean Willie.

The hi temp thermocouple I got came with ceramic spacers on the wires. I had planned to position the end spacer even with the inside so just the junction protruded, and hold it in place with a bit of furnace cement.

Tom