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Tools, Glorious Tools! #5 - The Pyrometer

🕑 Added 2018-02-26 10:56:47 +0000 UTC

Comments

Clickspring

Will do Pat - Cheers :)

Patrick Walls

Chris, love the TGL series, fantastic information for us new guys! Keep cup the great work. Pat

Jonathan Crider

*Note*: Take the following with a few grains of salt: I have ZERO practical experience with foundries - either industrial or home-made. Having said that, Tom Walker is absolutely right. I DO have a ROUGH idea of how infrared thermometers work, and even if you were to take the crucible out of the foundry, you're much more likely to get a reading of flames, hot gasses, or possibly slag that hasn't changed color enough to see very easily, than you are to get the temperature of the metal. Even if none of those are a factor, you'd only get a return from the top surface of the molten metal, which will absolutely be much cooler (relatively speaking) than the temperature of the other 99%+ below the surface, which is what you really need a reading of.

Tom Walker

Infrared does not perform well inside furnaces. And the ones capable of high temps are very expensive.

Clickspring

Very cool Sebastian - thanks for the info :)

Sebastian Rietig

And the coolest thing about K type thermocouples: The "balancing line" is made from the same material as the thermocouple itself. So when you just twist together the two wires in the cable you'll get just another thermocouple. So you can keep the excess wire, remove the insulation from the other end as well, twist and optionally braze them together and you can use it like any other thermocouple to measure temperatures of whatever you want. So you might want to keep the cut off cable :)

Clickspring

Not sure mate :)

Karl Mansson

Will an infrared thermometer work at these temperatures? One of those point n' measure things?

Clickspring

I mean the probe and the digital thermometer, but I guess the frame too - I just followed my nose on that one :)

Ralph McCoy

Chris, you mean the piping and all, that is something

Clickspring

Yes it is a relatively widely used combination - Cheers :)

Ralph McCoy

Chris, was looking at myfordboy video for today and when he checked the temperature, could not see all of it, it looked like the same gauge you have here. Ralph

Clickspring

So pleased to hear you're enjoying them mate - will definitely do more casting vids, its such a fun process :)

August frost

I love this series. You have so much knowledge and skill, and for some reason I love watching you make the molds for casting. Love to see a video on that subject cause I can tell you definitely found some tricks.

Clickspring

Thanks for the info Sebastian, I shall happily snip away in future! Cheers :)

Clickspring

Ha ha! Terrific to have you on board mate :)

Sebastian Rietig

A thermocouple is not a resistive sensor like a Pt100 or a NTC/PTC. A thermocouple is a combination of two different alloys that will create a voltage according to the temperature of the junction. A Type K is made from a nickel and a nickel-chrome-wire (NiCr/Ni). At 1000°C the function creates a voltage of about 40mV. The thermometer has a high impedance input, so nearly no current flows through the thermocouple and no voltage is lost in the cable. So the length of the wire does not really matter on a thermocouple. The cable is protected by a glass fibre sleeving to prevent it from melting.

Luther

Just became a patron! Love the quality of work you turn out, see what I did there, keep it up.

Clickspring

Ha ha! Cheers Mike :)

Clickspring

Not sure mate, its just an Ebay special: <a href="https://www.ebay.com/itm/NEW-10mm-THICK-CARBON-GRAPHITE-ROD-10x-300mm-LONG-MIXING-STIRRING-CARBON-ROD/281773690940?hash=item419b05503c:g:opQAAOSwgQ9VzljP" rel="nofollow noopener" target="_blank">https://www.ebay.com/itm/NEW-10mm-THICK-CARBON-GRAPHITE-ROD-10x-300mm-LONG-MIXING-STIRRING-CARBON-ROD/281773690940?hash=item419b05503c:g:opQAAOSwgQ9VzljP</a> - Cheers :)

Clickspring

I would certainly do so if there was enough interest mate - it does tend to make most peoples eyes glaze over a bit tho... - Cheers :)

Natan Getschel

Hey Chris, just became a patron and looking through all the videos (everything you do is amazing by the way) and was wondering if in a future video in this series you would touch on CAD? Your models of your projects always look amazing.

Mike Oswald

Sigh, another cool tool I now must build, thanks chris

John P

What exactly is that carbon rod - is it something you could make? I mean, probably it's cheaper to buy it, but could it be done?

Clickspring

Cheers mate happy to be the crash test dummy :)

James Cuddihy

You could also use carbon rods for air arc gouging. They are copper clad though, so might need to be seasoned in something that isn't mission critical before being used in your carefully weighed out alloy. If you don't need a lot of them a welding shop would probably give you a couple.

Clickspring

Clifton Ballad

I always kinda wondered how well sticking a thermocouple in molten metal would work, and now I know. You saved me a few nuked thermocouple leads and hours of frustration as well as providing the solution I didn't know I needed, Thanks Chris!

Adam

Cool

Clickspring

I'm not sure Damien - possibly the latter? Its quite a hard and brittle material, but not overly powdery.

Damien Miller

Great video as always! Are the rods that you use graphite or amorphous carbon?

Clickspring

All the best to you too mate :)

Gordon Burns

I see where you're coming from, my antipodean friend. I guess that cable resistance could well play a part in temperature reading, in which case the full length of cable would be beneficial... I hadn't considered that, Chris, to be honest but I am sure that the pyrometer leads will not be made from an electrically high conductor with a relatively low melting point such as copper, simply because they need to be rugged and to withstand temperatures way above the melting point of copper. So, we must assume that the pyrometer wires are made from a high melting point alloy, which carries with it (as a trade-off) a stated resistance of Ohms per Metre, so in which case I agree, that the full length should be utilised. I'm eagerly looking forward to the next Antikithera video, Chris... I play them back many times. All the best, Gordon

Clickspring

Hey Gordon, all good thoughts - no chance of snagging any cable, the braided sheath ensures that it slides through neatly :) Re the extra cable length, I seem to recall reading somewhere that the length may affect the probe temp calibration - That may or may not be the case, but I figured I'd rather not chance it since I have no way to check the calibration once cut - Cheers :)

Gordon Burns

Very useful tips in this video, Chris. Just a thought but you could've fed a 'mouse wire' down the tubing from top to bottom, then drawn back the pyrometer cables, so that the cables and sleeving were totally enclosed within the tubing for their entire length, negating the chance of snagging the cabling during use. I know how neat you are, mate, and note the neatness involved in coiling up the spare leads... only why do that? I also know just how exacting you can be Chris. I guess that the pyrometer and cabling are designation-specific to the foundry temperature probe, so why not chop the wires much shorter and fit the plug so that the leads are just long enough to make connection with the temperature gauge, obviating the need for the redundant coil winding (which could have a detrimental effect, resulting in spurious and inaccurate temperature readings due to electrical inductance within the coiled conductor, not to mention the possibility of catching it on something and either damaging it, or worse still, damaging yourself. As I said, Chris, just a thought and not a criticism, mate.

Ralph McCoy

Yes of course: temperature reading stabilizes I should have know that

Clickspring

Its hard to really know Ralph, but the carbon conducts the heat very quickly, and I generally leave the probe in the melt until the temperature reading stabilises - so I would be surprised if there was any meaningful differential/error - Cheers :)

Ralph McCoy

Chris, this carbon cover how accurate is it from the outside to the thermonuclear ? I guess it would be " in the ball park" 50 degrees or so is close enough or am I being too exacting ? Ralph I enjoy the video

Ralph McCoy

Chris, this carbon cover, how accruct

Clickspring

OK, terrific Vince - I have also put a link in the text above - Cheers :)

Clickspring

All good mate :)

Clickspring

Ha ha! Cheers Wes :)

Clickspring

Thanks Harold :)

Clickspring

I was a bit surprised at how quickly it was destroyed too! Cheers mate :)

Clickspring

Cheers Jon :)

Vince Endter

Never mind, I found searching for graphite rod came up with the proper results

Vince Endter

Where can I find the carbon rod? Do you have a link?

Theodor Kristiansen

oh my new vid was beginning to think the worst

Wes Baker

Thanks as always, Chris. Warm workshop at 28˚ . Wish we could have those temps in the northern hemisphere. Oh, and clever knockup probe as well. Always thinking and fiddling you are.