Installing thermocouple in a forge

Jesse Smith

Jesse Smith

Joined
Dec 2, 2013
Messages
163
Sorry, I'm sure this has been covered, but I've been digging around in all the stickies and attempting to search for the answer, but haven't been succesful.

How do you physically install the thromocouple/sheath in the forge body? Do you just drill a hole through the body, and stub the sheath up through the Kaowool, and use Satinite to hold it in place? Then, assuming that is right, what keeps the thermocouple in the sheath?

Oh, one other question:
In the stickies, Stacy linked to this PID... http://auberins.com/index.php?main_...s_id=1&zenid=90b32ac5f8da355dc0ed454b403f29f8 but said to use a SSR as well. I'm confused about the need for the SSR since the PID in the link has an output of up to 10 amps at 120VAC. Has the PID just been updated since the sticky was posted in '09 or is there another reason for the SSR that I'm missing?

THANKS!
 
Drill a hole in the top of the forge stick the thermocouple in and pack a little kaowool around and your done

The ssr is for turning a solenoid controlled gas valve on and off
 
I know the SSR is to turn open/close a solenoid, but the PID specs say...

One of the unique features of this controller is that the built-in relay can handle 10 A of current at 120VAC. That means 1200 watts of load can be connected directly to the controller without the need of an external relay or SSR. That is a very convenient for applications in which only a small heater is used.
Click to expand...

So I was wondering if I really need a SSR in addition to the PID, or if the built in relay will work to control the solenoid? I'm thinking the PID can handle it, but I'm a noob and want to make sure I'm not missing something.

As far as the thermocouple, I thought most of them are installed near the bottom of the forge where the knife would be?
 
As said, drill a hole, use satanite and wool to secure the sheath in place. Put the TC down the sheath, and pack the sheath with wool to keep it insulated and snug.

As to the SSR, it is an electronic isolation from the control circuit. Relays fail after thousands of cycles On/Off, but the Solid State Relay does not, even after millions of cycles. Also, the load on an SSR can be much greater than that of the relay in the PID. You could run the solenoid off the PID, but I would rather use an SSR.

There is also an additional reason to use an SSR. It makes the PID controller capable of handling higher and resistive loads. That means you can unplug the controller from a forge and plug it into a toaster/tempering oven or such for controlling that device....or a quench tank heater....or a low temp salt pot.....or whatever you want to control.
 
Quick question. I usually run a muffle inside of my forge. Would I still want to go through the top of the forge and then make a hole in the top of my muffle and run my TC lead down into both of them? Or can I simply run my lead in the back of the forge and into the muffle and let it lay on the floor of my muffle? Thanks! Don
 
With so many different forge configurations, I would think any place inside the forge that keeps the thermocouple out of direct contact with the flame would be good, contact with the flame would drive the PID insane I think
 
Thanks for clearing up my questions. I knew there had to be reasons for everything, i just need to ask questions and make sure I understand why I'm doing stuff a certain way. :thumbup:
 
Yes, you will need to drill a hole in the muffler pipe to get the tip of the ceramic tube inside the muffle pipe - this will improve the ability of T/C to read the temp inside the muffle pipe where the blade is.

Ken
 
Talk about threading the needle? Getting my hole in the muffle lined up close enough to match the hole in the forge will be a bit of a challenge. But, I can do it!
 
Thanks Stacy,
I figured I would post a separate thread rather than derailing the original one here. I appreciate the info! Don
 
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