I just got around to ordering a pyrometer. Of course, I was advised that the probe could not handle the temperatures that we run in our forges.

Ed; do you leave your probes in the forge all of the time, or just long enough to check the temperature?

Hi Steve!

I leave them in all the time. I drill a hole through the forge shell/refractory, insert the thermocouple, with about 1/2-1" of it inside the forge. My PID is mounted on the front lip of the forge table, with a cord running to the nearest outlet.....it's become habit for me to fire up the forge and then plug in the cord to the PID. I've learned that a thermocouple rated for 2000F will last about 6-8 months in my welding forge, and MUCH longer on my general purpose forge (which tops out at about 2000F).

If you plug the PID in one day, and see a line of "E" across the readout, or the temp is jumping all over the place, it's time for a new thermocouple. You will also see a line of "EEEEEE" across the PID if you exceed the max. readout temp of 2500F......that doesn't hurt the PID, but tends to burn up thermocouples pretty quickly.

Ten years ago when we first moved to MT from MO I was having trouble getting good welds. Figuring it was a temperature issue due to the altitude change I purchased one of the high priced Pyrometers from a ceramic supply house and loved it. Early last year it went bad so sent it in for repairs but these folks told me it could be some time before I got it back so went looking for help. I found the little PID just like Ed uses for $20 on ebay so ordered it thinking if it worked till my old one got back I'd be tickled... That little rascal is still working great and I like it better anyway since it has the lighted display and is easier to read in low light.

I use the K type probes also and would also add that you can get a ceramic tube to slide it thru in the forge. This protects the probe and it should last for years. I drilled a hole thru the outer jacket and ran the tube into the fire chamber about half in the insulation and half out. Just don't paint over the tube with any of the forge coatings, it really impedes accurate temp readings... <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//rolleyes.gi f' class='bbc_emoticon' alt=':rolleyes:' />

I use them at my day job and borrowed one when I started forge welding to relate temperature to color. I ended up buying one from Omega (we use Omega at the lab and the service is excellent). The lower temperature ones aren't bad in price(1335 C or about 2440 F - sorry I then to think in C outside of cooking temperatures - for about 30 USD - controller is another hundred at list I think)and you can get higher temperature ones (up to 3400 F in a forge...higher if it never sees oxidation) which are more expensive (100-250 bucks), but then the controller really hurts on price (I think the cheapest was 400). We have one set up for molten metals for casting where we got a used rebuilt controller and a used probe from lab that was selling stuff off when they shut down and even that way it was pricey - but it will read the temperature of molten iron.

There is a book on how to hook these to a gas forge and control with it: Digital Temperature Control for the Blacksmith Forge by Potter. We have it but as a hobbyist I haven't found time to try it. It's pretty readable. I've redone old muffle furnaces for the shop and that was easy. The gas makes this a little scary - I really should though as the TC says my color sense with hot steel sucks...

I use a small PID and TC like Ed. I cut a power cord off a defunct lamp (with a built in rocker switch) for power.

If someone is looking at this thread down the road and the eBay link posted above is kaput, you can get the PID directly from Auber Instruments ( http://www.auberins.com) for the same price. They specialize in thermal controllers and such. They also have the manuals to their products available on line. Here's a link straight to the PID, Universal 1/32 DIN PID Temperature Controller.

I have found sourcing high temp type K thermal couples can be more challenging than the the PID. This $18 one of Auber's is rated to 2,000F: K type high temperature thermocouple for heat treatment. They have a $25 ceramic insulated one rated to 2,300F: High Temperature Thermocouple for Kiln.

Anyway, like Ed said, for not much more than $50 you're in business, AND, when you're ready to make a controller you're all set. Just add a SSR for an electric one, or a solenoid for a gas one.

BTW, the first time I did this I bought one of those high-fa-loo-tin capped ceramic tubes for a baffle to insert the TC in (like some folks use a piece of pipe for). Broke the bugga first time I used it in a hot forge when I hit it with the bar of steel I was heating. So be careful if you try that approach.

Hey Guys,

I really appreciate all of the advice!

I ordered the Therma-K meter, with a high temperature industrial probe. The probe is rated to 2012 degrees and the sales rep said that he couldn't promise it would stand up to higher temps. That's why I asked Ed if he left his probes in the forge. I may want to order one like he uses; if the probe that comes with my meter doesn't last. I seriously considered purchasing a PID , but time is money right now and I wanted to have something that I could put into service quickly.

I am still struggling to complete a project that caused me to initiate this thread. The project requires a complicated series of forge welds. The piece must be in the forge for a very long time as all of the welds are made. The problem is that I can get about 90 percent of the welds made, and the remainder of the welds refuse to close. I cannot understand why this is happening. I've lost about a month's worth of shop time this summer due to bad welds on this project.

I have tried four different fluxes. Stopped and cleaned the piece during the welding process. And tried every means that I can think of to mechanically close the welds. The last piece that didn't weld, I sand blasted, wire brushed and acid etched it until I was absolutely certain that it was sanitary, with no scale in the open welds. I fluxed it with anhydrous borax and tried to close the welds. They still wouldn't weld. I am totally perplexed as to how I can complete hundreds of welds on this piece and then part of it becomes unweldable. Is the flux not capable of withstanding the length of time in the forge, the steels not a good choice for this project, the atmosphere in the forge wrong??????

I thought that maybe the flux was being destroyed by the length of time in the forge and perhaps too high of welding temperatures. My forge is capable of running very hot; I think. Thus, my reason for ordering a pyrometer. Too, I want to check the atmosphere in the forge. I want to make sure that it is not oxygen rich and causing excessive scale. It seems logical to me that increasing the gas inflow until the forge starts to run cooler would indicate a reducing atmosphere. Once I have an understanding of the conditions in the forge, I will consider different fluxes and steel combinations. I am determined to figure this out!

I ordered my K-type probe from Omega. I called and told the rep what I was going to use it for and that I needed it to be able to withstand up to at least 2300 degrees. He checked with a tech in the lab and said that they would build one for around fifty bucks. I've had it above 2300 with no problems. They are real easy to work with. Just tell them what you need and they work with you any way they can.

I wish I could suggest something on your welding problem, but I ran into the same thing recently. Never did get that stupid weld closed.

Dale

Dale,

Thanks for the information about Omega being able to build special probes. With yours and Ed's information about probes, I should be able to find a good one, if needed.

I received the unit from ThermoWorks Friday. I was welding damascus at the time, so was able to check the forge. Had it up to 2400 degrees. The probe held up, so far.

That sounds great Steve. I don't use mine a lot, but it comes in handy for heat treating. With a little tweaking I can regulate my forge to whatever temperature I want to harden a blade. Sure beats trying to guage colors.

Dale

They also have this same model in 12v or 24v.