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Inexpensive infrared thermometer

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  • Inexpensive infrared thermometer

    I am looking for an infrared thermometer to measure temperature of steel in my forge.
    I don't want to spend a fortune but would like to have a better measurement than the color of the steel.
    Anyone know of a good cheap thermometer for this application?
    Bill
    I cut it off twice and it's still too short!

  • #2
    More along the line of what not to try... I have used the Harbor Fright infrared hand held unit without much success. Trying to read the temp in a gas forge is tough... the refractory is hotter and much greater in size.
    Unless you need to control the temp for heat treating, in which case you would be better served with a thermocouple in a sheath located in the heat-treat oven, The eyeball doesn't work to badly after some practice.
    It only took me ten years to judge forge welding temperatures by eye :>)


    paul
    paul
    ARS W9PCS

    Esto Vigilans

    Remember, just because you can doesn't mean you should...
    but you may have to

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    • #3
      I have had a coal forge in Minnesota for 10 years and now have a gas forge here in Indiana.
      Looking at the color has worked "sort of OK" up till now but I want to try some more exotic steels for knife blades.
      I thought an infrared thermometer might help.
      I have searched but can't find a unit under $300. That's a bit much for not much more capability over my eye.
      The only one I see on the Harbor Freight website is limited to +400dF. Thats way to low for forging temps.
      Maybe I'll find one I can afford on ebay.
      Bill
      I cut it off twice and it's still too short!

      Comment


      • #4
        You can buy ceramic temperature cones for pretty accurate temp determination at any pottery supply. They droop over at the calibrated temperature, single use only but relatively cheap.
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          Orton pyrometric cones will not work properly for this application. They don't just react to the temperature, but also to the heating rate. It works perfectly fine for ceramics, but not for heat treatment of metals (unless, of course, you can guarantee a consistent ramping rate and then calibrate the process for a particular cone number). But it won't be as simple as "use Cone 04 for 1945F". At the same time, such things as temperature crayons used in welding would be suitable for the application.

          I bought my Smart Sensor AR872D infrared thermometer (pyrometer) brand new on eBay. It works more than decently and was a way less than $300. I don't remember exact price, but I think it was around $100.

          I used it in my electric kilns and compared with thermocouple readings. The readings were identical. The trick is to focus it on the surface you're interested in and have no overheated parts around. Doing it inside a working gas forge will not produce reliable results for the reasons mentioned by Paul (unless the part is very large). However, if you remove the blade from the forge, the reading will be reliable. If you had an electric kiln, you could measure directly as long as you don't point to the hot coils. Same with a heat treatment with a torch: heat the part, remove the flame, measure.

          EDIT
          P.S. Here is one: http://www.ebay.com/itm/NEW-AR872D-N...item336de2895d (I don't think the seller mentions a correct temperature range. Mine is from -50C to 1100C which is from -58F to 2012F)
          Last edited by MichaelP; 05-31-2013, 12:43 AM.

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          • #6
            You are looking for what is called an optical pyrometer. They are not cheap, a few on ebay.

            http://www.ebay.com/itm/ANTIQUE-GERM...item4abb708764

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            • #7
              I have a Raytek Raynger ST80 and it has worked great for years. But it only measures up to 1400F. It was expensive eight years ago but very affordable now. JR
              My old yahoo group. Bridgeport Mill Group

              https://groups.yahoo.com/neo/groups/...port_mill/info

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              • #8
                DX carries lots of thermometers - perhaps worth looking if they have something suitable...

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                • #9
                  Specifically this one, rated to 2372 degrees F with sensor and only $30 with good reviews.

                  http://dx.com/p/k-type-digital-indus...-c-1300-c-7286

                  It uses type K thermocouples and you would probably want one with a much longer probe like this one for $4.90:

                  http://dx.com/p/k-type-thermocouple-...er-grey-213591
                  Free software for calculating bolt circles and similar: Click Here

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                  • #10
                    The problem with the thermocouples is that the thin wire ones have very quick response, but cannot withstand high temperatures. The thick wire ones are very slow, but can go very high. The ones that have a protective shield (as the one in the link) are extremely slow, but in a reducing atmosphere of a fuel forge, I'm afraid it'll be the only reasonably priced option.

                    Consider buying thermocouples, connectors and K-type extension wires at Omega. I had a very negative experience with the cheap Chinese ones sold everywhere: everything from wrong wires that only look like K-wires, wrong "look alike" connectors which, in addition to everything, were wired incorrectly, defective couples, etc. Omega has an excellent tech support and customer service.
                    Last edited by MichaelP; 05-31-2013, 04:05 PM.

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                    • #11
                      With a type K like the one I linked you can easily run the wires inside a pipe to act as a handle. If you add a copper contact block to the end of the thermocouple it will change temp quickly and be relatively immune to radiation from other surfaces, especially if you shield the contact block with a metal cover that exposes just one side.
                      Free software for calculating bolt circles and similar: Click Here

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                      • #12
                        Thanks for the input.
                        Several good suggestions here.
                        I think I'll buy both the optical pyrometer on eBay and the thermometer and probe from DX.
                        $150 for both.
                        That I can afford and one will surely work.
                        Bill
                        I cut it off twice and it's still too short!

                        Comment


                        • #13
                          This is what I mean by a contact block and cover. This will make it very selective and faster responding. Use a stainless cover and screw to clamp it to the couple. Stainless has very poor heat conductivity so it will not quickly absorb surrounding heat to affect the reading.

                          Free software for calculating bolt circles and similar: Click Here

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                          • #14
                            I don't think 1000 deg F is what your looking for but if so Enco has an IR Extech mod 42350 for $78.95-30%, $55.27 w/free shipping. See the end of the last Enco thread.
                            "Let me recommend the best medicine in the
                            world: a long journey, at a mild season, through a pleasant
                            country, in easy stages."
                            ~ James Madison

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                            • #15
                              Thanks Flylo
                              I need the ability to measure about twice that------
                              Evan
                              That's clever! When I have time Ill try it. I have a piece if stainless tube that will work for a shield.
                              Bill
                              Last edited by Seastar; 06-01-2013, 10:18 AM.
                              I cut it off twice and it's still too short!

                              Comment

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