Recommendations for propane forge temp gauge?

D

dmelton

Joined
Jan 2, 2001
Messages
164
Anyone have a recommendation for something to accurately tell me what the temp in my little propane forge is?

611867c78e00b8160ec361fffa674ebd.jpg
 
Hmm, I'm not sure I want to put a lot of money into a forge that cost me a few bucks to make. ;) I wonder how accurate those infrared thermometers are?
 
it looks like the ceramic blanket in your forge is uncoated. this could cause the ceramic fibers to blow out of the forge while running. Not a good thing for the ol lungs. Recommend coating with something like satinite.

I've always struggled with the idea of a thermocouple in a forge. I suspect there is a lot of variation of temps throughout the chamber and you are not actually measuring the temp of the steel. curious to see what others have to say.
 
an infrared thermometer that will measure up to 2k will probably run more than the thermocouple...

http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=39 27$

http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=14 35$


the only IR thermometers I could find were over 100$ and didn't reach 1400 degrees...

plus you can later use the PID and thermocouple to make your forge a PID controlled forge later on, when you have more cash to blow on your hobby!
 
I use an Omega KHIN-14U-RSC-24, about $60 shipped
and this unit I got used off ebay - Omega HH-26K Digital

Jerid's probably right, but this is just another tool to use.

8EF45A1E-5BF5-457D-8DB0-420E284F5B61_zpsebsrfeng.jpg
 
For most purposes, a type K thermocouple is good enough. The upper end of its range is high enough to check a forge is getting to welding temperature (given that this is a bladesmithing forum. If you are intending to weld Wrought Iron, you'll probably need to go to a Platinum-based thermocouple, which is rather more spendy).

HSC/// seems to have a similar idea to me, though I'd use the Omega KHXL-14U-RSC-24 thermocouple. It's basically the same thermocouple assembly, except that the sheath material, "Super Omegaclad XL", is claimed to be good to 1335 degC/2440F. Inconel 600 is usually considered good to 1100 degC (2012 degF)

http://www.omega.com/pptst/KHXL_NHXL.html

The part number builder on that page will not allow the 24" length, but putting the part number in the search box (top right) will get you the price ($57.00 today, $3 more than the Inconel version).

For a readout, I recommend a search on ebay for "TM902C". It should run to between 5 and 6 bucks delivered (albeit not very fast) and just works. I have had a couple of dozen over the last year or two and put them on the calibrator at work. They have all been as accurate as big-name branded pyrometers costing 20 times as much. At the price, I have been quite happy to leave them on site for the local guy to use. The only downside I can see is that they only read in degC. They come with a 3ft-long glass-fiber insulated bead-type thermocouple that is good to 400 degC/750 degF and is flexible enough to fit through the gap round an oven door: ideal for checking most tempering setups. Whatever is marked on the front (750 degC, 1300 degC, etc.), all the TM902Cs I have tried have read to between 1365 degC (2489 degF) and 1368 degC (2495 degF).

The 1/4" diameter is rigid enough to use to profile the temperature in a horizontal forge and the 24" length gives your hand a good chance of staying out of the heat (though if you've got any kaowool left from building your forge, poking the thermocouple through a square of it to use as a heat shield is a good idea).
 
I'm currently out of stock, but a setup like this sells for $35 shipped. Most DMM can display temperature in °C up to 1999°.
TC_small.jpg
 
Atlas Knife Company said:
I'm currently out of stock, but a setup like this sells for $35 shipped. Most DMM can display temperature in °C up to 1999°.
TC_small.jpg
Click to expand...

I got one of those and the thermocouple melted off in my welding forge first use. Not sure what they are rated for but I was running about 2300 F. I had to get a much thicker thermocouple with a ceramic sleeve for something that actually stays in the forge continually.
 
Jerid, my blanket is coated, it's just an OLD coating and has flaked in a few places. It's bleached as white as the kaowool now so in pics it's hard to see. I do need to re-coat it though. Thanks for the heads up!

NickBoyle, that looks to be the ticket. I don't need precise, I just need something a little more reliable than a magnet and judging color. If this kind of forge pyrometer works well enough, I could forego the heat treat oven build for a while longer I think.

Thanks!
 
Yeah, that's more than it's rated for. Ideally, these are for temporary use only, Just long enough to learn the temperature/color relationship. After that, you shouldn't need the thermocouple. If you want to leave one in all the time, it definitely needs a ceramic sheath and probably a B, C, R, or S type thermocouple. Type K is only rater for 1250°C

JMJones said:
I got one of those and the thermocouple melted off in my welding forge first use. Not sure what they are rated for but I was running about 2300 F. I had to get a much thicker thermocouple with a ceramic sleeve for something that actually stays in the forge continually.
Click to expand...
 
You must log in or register to reply here.
Back
Top