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propane forge pyrometer advice


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Recently acquired small knifemaker propane forge. Have everything ready to go except for a pyrometer. Would like advice on type (affordable), where to buy, estimated cost, installation, etc.

Another question: Like to work with 154CM (or 154CMP or CPM?) for knives, and am told I need to "soak" it at hardening temperature (1950 f.) for two hours. How critical is the EXACT temperature and time?


paulallen, greencastle, IN

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Welcome to the forums, Paul.  Help us all out and put your location in your profile.  Odds are there are IFI members living near you.


As usual, I am by far less knowledgeable than others who may be here to answer later...but I can predict what they will say:

  How long have you been making knives and what equipment do you own!  If you are new to it (as it would seem since you just got a forge) then you want to put working with CPM steels and the like onto the wish list and go get yourself some 1095 or 1084 steel.  Also, get some old farriers' rasps or even some mystery steel just to practice shaping blades.  It would even benefit you to get some mystery steels and learn all the methods of testing them in order to determine how they should be quenched and tempered.  That way you will understand "why" steels are treated certain ways and not just learn "what" to do.

If you have loads of extra cash then you can jump right into high tech steels.  You will need a very expensive, programmable oven because it isn't just about the temperature it soaks at, but the rate of increase and decrease in temperature is measured as well (I believe).  I also believe that people finish the temper on those steels with a cryo bath.  In short, if you are new to knife making then you are shooting for the stars.

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Welcome aboard Paul, glad to have you.

Wow, that was really well said Lou, your experience shows.

If you'll put your general location in the header it will be there every tie you post, just saying it once in a post won't stick in our memories after we open another one or start writing a reply to yours. 

I'm not a bladesmith guy but I have experience working with all kinds of steels for what ever the purpose. My advice is you learn blacksmithing to a decent level of proficiency before you start working with specialty steels. That gives you ONE learning curve to climb, once you  know how to make steel do what you want learning how high carbon or high alloy steels move is only a matter of adjustment, not square one. 

Make blades though, do stock removal these are skills sets different from those used on the anvil and you'll need them to make good blades anyway. Learning grinding, dressing, fitting and finishing don't interfere with learning to forge. Separate learning curves that don't cross. 

We love pics, show us your: work, shop, tools, kids, pets, yard, anything you'd show a little kid you didn't want to explain.

Frosty The Lucky.

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Lou -- Thanks for the advice. Been knife making since the '70s, starting with "recycled" files, scrap steel, purchased (non-stain) and then purchased stainless. (Nothing worse than a rusty knife . . . except NO knife . . .) Had early stainless (440C & 154CM) heat treated by Paul Bos. Made about 50 knives, sold some, gave some away. Then moved on to other hobbies. Resumed about 10 years ago (retired), now I'd like to heat treat my own stainless. Won't invest much in the effort, since I am too lazy to "market" my knives. I'm aware of still-air quenching, cryonic stress relieving, etc. Stress relief is mostly to preclude warping. Still-air quench (I assume) isn't an absolute necessity. I'm assuming (perhaps naively) that if I can manage the hardening "soak," I can prevent warpage without cryonic stress relief, and can quench stainless with an oil quench. If that's incorrect, I'm sure someone more knowledgeable on this forum will so advise me. My PRIMARY question was about locating a pyrometer. Do you have advice on that?

Frosty -- Thanks to you, too, for the advice. I appreciate both your and Lou's taking the time to respond, but I'm not a "beginner." As I mentioned to Lou, I made about 50 knives in the '70s, and another couple dozen in the last decade or so. I work with stock removal (belt grinder and lotsa filing). I can't afford to invest hundreds/thousands of dollars into what is just a hobby for me, but I would like to be able to process stainless blades myself. Both you and Lou appear to have extensive experience with various steels. One question: Is there ANY stainless suitable for knifemaking that does NOT require the extended hardening "soak?"

If you both indicate that it's impossible to harden/quench/temper stainless without expensive equipment, perhaps I'll shift gears and try to get back into black powder rifle building (have about three dozen of those completed over the years, but stopped because the parts folks are getting a bit too "proud" of their wares . . .). Maybe get back to the guitar and violin.

Thanks much for the advice. STILL WOULD LIKE ADVICE ON A PYROMETER. My apologies for cluttering up this forum.

-- paulallen, greencastle, IN

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Hello Paul Allen. I use a K type pipe fitting style thermocouple that is made of Inconel with a mini connector. Then I use a thermocouple readout that will read a K type thermocouple.  You can get the readout from a lot of different places, but it's not worth skimping on the thermocouple itself.  The most recent ones I bought from MSC were from Thermo Electric. Omega Engineering is another good thermocouple source. I paid about $120 for two of them.

As far as metal and following heat treat guidelines, I would say following the recipe is pretty important.  If you don't want to invest in a Heat Treat oven, then I would do what you said you did before, either use Bos or Peters Heat Treating is supposed to be top notch. 


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Steve -- Sorry about that. I should have spent more time perusing the forum, clearly, to see that I was in the proper section (there are LOTS of categories . . .) I'd become frustrated trying to get some straightforward answers to two specific questions, got excited about finding a forum where I might find answers and rushed a bit too much.

My apology! I'll try to do better the next time . . . honest . . .

-- paul

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Here is a write up I did a couple of years ago.

How I got my Pyrometer.  September 15, 2015 by Wayne Coe


I have had a number of people ask me about how to get a Pyrometer like mine so I decided to write up this little sheet.


I have the PID that you can find at this URL. 


There are a number of other companies that sell this PID and there are other PIDs also.

Last year I paid $28.42 including shipping but now I see that it is $28.95 plus shipping.

With this PID you must also supply your own power cord so there is another expense, unless you can source a power cord from an old extension cord or something similar.


For the Thermocouple you can use this URL.  http://www.omega.com/pptst/TJ36CAXL_NNXL.html

These come in 12” and 18” probes.  For a 12” probe you can  order a TJ36-CAXL-14U-12.  I just priced that out and it came to $44.00 plus shipping.  Remember that the reading comes from the very end of the probe only.  The tip of your probe needs to be in the area that you are measuring the temperature.  In the case of a Ribbon Burner that would be in the center of the burner.  I have mine lying on the floor of the forge. 


I mounted my PID in a double outlet box and used the plastic outdoor type box which is gray and is waterproof and dust proof if you use a cable gland for the connections.  I ran both cords out through the one cable gland.  Keep in mind that the probe is somewhat fragile when hot.  You need do devise a method of securing the probe in the forge and the PID so that they don’t fall or otherwise get moved around while you are working.  I drilled a hole in a fire brick to extend the probe through and mounted the box to my forge stand.

To program your PID for temperature control I found this on www.lightobject.com support forum.


Re: JLD7100 PID Temperature Controller Setting

Postby cumorglas » Wed Sep 08, 2010 7:17 pm

press the set button
using the arrows to move the blinky bit over and the numbers up and down make it say 0089
then press set again
use the up and down arrows to get it to to say inty
then press set again
use your up and down arrows to get it to say k which doesn't look like a k at all. it sort looks like this
|_|  It looks more like a backward

then press set again
then use up and down arrows to make it say end
then press set again
then you should be fine and able to tell what temp it is wherever in your forge you put the thermocouple. make sure it can handle the range you need. if not k thermocouples are not terribly expensive

Be sure that Fahrenheit is the temp setting -- CorF = 1.

Good luck and Let me know how I can help you.


Wayne Coe


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I should have put the "if" in caps!  Paul, I was honestly trying not to assume you didn't have experience, hence my "if".  But I understand how it campy be annoying to get novice answers to experienced questions.  I answered the secondary question because it was within my ability to give some input.  I'm slowly moving toward building my first propane forge currently and have only done limited reading on pyrometers and thermocouples.  In fact, the repost Wayne just shared was the beginning of my learning journey on the topic.


Im sorry I can't suggest a stainless steel that can be heat treated without an oven.  I'm unaware of one.  Even 440a is tricky without an oven.  If you are able to get excellent control of your forge by controlling the propane and air you may be able to get good results still.  The pyrometers will teach you how to control the forge enough to replicate the effects of an oven. It's what I hope to be able to do down the road because I don't expect to ever own a heat treat oven either.

I'm confident that our gas forge gurus can get you to a place where you can control the temp of your forge.  If you get a thread started on that topic I'll be reading and learning from it as well.


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The soak is not to prevent warpage it is to solutionize all the weird carbides high alloy steels can have so you can get a nice fine grain when you quench.

The cryogenic quench *AFTER* the normal quench and tempering for the alloy is to deal with retained austenite; which high alloy steels tend to have more of than plain steels. Note that the cryogenic quench changes some of the retained austenite into martensite----which you then need to do a repeat of the normal temper on!

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Lou -- Thanks. As Will Rogers wisely said, "We're all ignorant -- just about different things." At this point, I'm woefully ignorant about how to make stainless steel work for me in knifemaking at a reasonable expense. I'm trying to fix that . . .

Tom -- Thanks much for the great pyrometer info. Just what I was looking for. I'll put it to use! -- paul

Frosty -- Thanks for the advice. I do stock-removal. My non-keeper knives have been sent to an Arizona friend who has a fine arts shop for potential sale. I'm trying not to clutter up this great forum with non-useful material; my shop, kids, etc. ain't all that exciting, anyway . . .-- paul

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