Adding a second TC to oven

melsdad

melsdad

Joined
Apr 3, 2008
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I want to have a backup temperature reading (second opinion) to monitor the temp. in my oven/kiln. I have done the searches, and it is recommended that a second PID and type K TC be used. I just want to clear up any details before ordering the extra PID.

Is this the correct PID for basic temperature readings:

http://auberins.com/index.php?main_..._id=14&zenid=9465d6654ecb279cca762e86c80cf73c

I would obviously need the same TC I already have for my main ramp/soak PID controller.

http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=39

Also were is the best location to have the temperature only TC in the chamber?
 
Those will work fine.

The advantage of using the same components as the main controller is that if a part fails, you have a back-up already there. Move a few wires and you are back in business. Redundancy is a good thing sometimes.

Using TC plugs and sockets allows the PID to be moved from one task to another easily,too. I don't recommend moving the TCs around, because they get brittle after firing a few times. You can get many shapes of the cheap Chinese TCs from ebay and use them for reading the temp on your quench tank, the shop temp, your tempering oven, etc. and move the PID around as needed. In places where it counts, like the forge or a HT oven, use a good quality TC and a ceramic sheath.

If you haven't looked at the project boxes and plugs/sockets that Auber carries, take a look -
http://www.auberins.com/index.php?main_page=index&cPath=7

Installing a TC sheath to slip the TC into from the outside is the way to go for durability and good readings. Make an entry port where the TC will be placed.Weld on a port tube, just like you do for a forge burner. Use a piece of pipe that fits the sheath with just a little room. Mortar the sheath in place with satanite. Once the TC is inserted into the sheath, pack the sheath around the leads with wads of Kaowool. Pack everything that sticks out of the heating chamber.
Here is the sheath most folks use -
http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=40
 
O.K. Stacy so you are saying make the second PID portable? I was going to mount the temperature only PID in the control panel under my main PID. For how cheap the parts are I may still make this a dedicate sytem, and build a portable unit down the road.
 
A dedicated system is always the most robust, so if it isn't a financial burden, that is the way to go. Mount both in the box. I would still install TC sockets on the back of the box, and plugs on the TC leads. This makes changing them easier. It also allows a different TC to be plugged in to the read only PID when needed ( like one from the quench tank).
 
That is what I will do then Stacy. I did not mention it, but I do have the TC sockets for the connections. I like the idea of being able to plug in another TC to check quench oil temp., and possibly even the secondary temperature of the tempering oven.
 
The TCs with a 1/4-20 bolt end are super for adding temperature checking to things like the shell of a forge, or a quench tank. Just drill and tap a hole and thread in the TC. Some sealant may be needed on liquid holding tanks. In other circumstances, just weld on a 1/4-20 nut and thread the stud TC into it until it bottoms on the surface being monitored.
TCs can also be purchased cheaply with end rings that are put under a bolt head.

Places that the threaded end or bolt on TCs work well are:
The forge shell
The burner tube
The manifold in a venturi forge
The aluminum plate in the toaster oven
The work cart under the forge
water pipes
The back of your grinding platen
Any place where friction may be a problem
The propane tank
The anvil ?
Tong handles?
 
If you use plugs and sockects make sure and use extension wire that matches your TC type. Using copper wire can introduce another voltage into the loop. Also, as another option, what about using a datalogger as your back up? You can monitor temps real time and review the whole HT cycle.
 
stevomiller said:
what about using a datalogger as your back up? You can monitor temps real time and review the whole HT cycle.
Click to expand...

Do you have an example of such a thing?

We have chart recorders on 5 of our furnaces at work, but they would be more expensive than my whole build.
 
Hey Melsdad,

If you do build a second senser setup, would you be kind enough to post part #s and how it works out for you?

I'm planning on a second TC in Jan or Feb and would love to have the headstart!
 
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