How bad could it be? Infrared Thermometer from HF

[donnrcp]

115928Any body have one of these? Good to 968 degrees F, +/- 2.5%

[theperfessor]

Mostly useless for any purpose related to bullet casting. Sorry, enough stickies here about these saying the same thing.

I've got one and use it for several things but not casting.

[kencha]

Yeah, pretty much no good for measuring the temp of melted lead. I don't think that one can be adjusted for emissivity (couldn't see any mention of any adjustments in its manual). So it is not going to be accurate. Besides, lead's emissivity varies quite a bit between its solid, possibly oxidized state and the shiny molten state. Lead is just not a good candidate for IR temp monitoring.

You can try tricks like measuring the temp of the ashes if using sawdust as flux, or some such. You're just getting the surface temp of the ashes though.

Better off getting a standard thermometer, or even better, using a thermocouple with a PID.

[theperfessor]

They are good for finding air leaks and insulation problems by spotting warm spots around your house from the outside. They are good for other things too, just not for most casting purposes. A good analog thermometer isn't all that expensive and a good PID is the way to go if you have a few dollars more.

I wasn't trying to come down on the OP or be curt or short, but there have been many threads about these things, including at least one with some great test results. All show poor results compared to other temperature measuring tools.

[el34]

I bought one on sale but haven't done anything with it. I thought I'd spray paint one side or the bottom of a mold with hi-temp flat black engine paint (great emissivity) and rig up a simple fixture to have it measure mold temp between casts, and without having to pick it up and aim it. Probably clamp the trigger ON and power it with an AC adapter. I can picture just passing the mold over it or next to it without changing hands and see what the screen says.

[oneMOA]

I bought one on sale but haven't done anything with it. I thought I'd spray paint one side or the bottom of a mold with hi-temp flat black engine paint (great emissivity) and rig up a simple fixture to have it measure mold temp between casts, and without having to pick it up and aim it. Probably clamp the trigger ON and power it with an AC adapter. I can picture just passing the mold over it or next to it without changing hands and see what the screen says.

The high temp paint may not withstand the brake cleaner or other solvent/degreaser that you use to clean your mold before casting. I use an IR thermometer for checking the temp of my cast iron mold and it seems to work just fine. A aluminum or brass mold would probably work if you smoked the bottom or side of the mold and read that spot. Mine is not made by Harbor Freight and there may be a quality difference explaining why mine reads OK and others don't. In either case of the mold material, the sprue plate should read fine as it's black and not reflective.

[el34]

In either case of the mold material, the sprue plate should read fine as it's black and not reflective.

Bingo. The HFIR meter is now on the project list, about halfway down.

[dragon813gt]

The sprue plates are reflective. They are not a truly flat surface. We use black grip tape at work if we want to know the temp of pipes. That is the type of flat non reflective surface you need for the IRs to work somewhat well. If you search for the threads I've made there is one about IR thermometers w/ test results. I had a FLIR camera that I tested at the same time. Neither one is good for casting.

[el34]

I still might try flat black engine paint on a side or bottom of a mold in an attempt to measure its temp. The PID does great for the lead, don't need no stinkin IR.

I have an NOE mold with the hole drilled in one block for a probe. I might try finding a small TC-based temp readout module that I could velcro to my arm to monitor mold temp while casting. And pull out the probe or unplug it if I need to set the mold down. Dunno.

[Mike W1]

Just for giggles I removed some paint from a spot on my LAM II and painted it flat black. I could MAYBE detect about 1° F difference than the area next to it. I believe that the IR's really aren't suited to our needs just like most of the posts have said. I saved a post from some place or another written by someone that knows quite a bit about them and certainly can't argue with what he said. My PID controls my heater and I do find the IR useful comparing a shot at the reservoir to know when it's ready. Just don't think I'm getting an actual temperature reading with it. Doesn't matter for that anyhow.

[Dale in Louisiana]

Throw a steel washer on the top of your lead in the pot. It will oxidize to a good, emissive dark color. Aim your IR thermometer at it. You won't be measuring exact temperature, but if you use the same target from one day to the next, you will be able to determine if you're at the same temperature, and if the target says the temperature is changing, then it IS!

I've been doing infrared thermography since the late 1980's. One trick I learned was that instead of changing the emissivity with each different specimen, measure the temperatures between like objects. That's what you're doing with the oxidized washer - making your very own 'like object'.

Same goes for the temperture of your shiny aluminum mould - you won't know the EXACT real temperature, but if it's casting good today at temperature XXX, then tomorrow when you get it up to temperature XXX again, it should do as well.

dale in Louisiana
(Does anyone know what a Hughes Probeye is? I do.)

[dikman]

Interesting idea about the washer. You could measure the temp and then compare it to the PID setting, that way you may be able to work out some sort of table to calculate what you're reading from the IR unit compared to the PID.

Of course, if you've already got a PID it's a rather pointless excercise.:roll:

[jmorris]

A friend picked one up the other day and I played with it. Hated the fact that it always goes back to C when it times out but it sure cost a lot less than my "good one".

[Garyshome]

Those babies are real handy, I use mine all the time, got a great deal on it a while back. [Check the temp on the hot plate]

[AggieEE]

Dale in Louisiana, Yes I know what a probeye is. I used to work for Tandy Corp building the TRS80s and got the loan of a small one as an experiment. With the computer board running you could see the different traces on the board light up as the lines were turned on and off.

[jmorris]

I used to work for Tandy Corp building the TRS80s ...

That dates you, 30 minutes playing back a cassette tape to load a program in the computer. Ah, the good old days.

[bangerjim]

Good for most temp reading.....except the ones we want! IR does not work on shiny surfaces (black body radiation for physics class). I use them for duct temps, steam temps, process water, solar panels, etc in my company when a Flir IR camera is not available.

I use BirchwoodCasey Aluminum Black on the side or end of Al molds. It is NOT a paint so it will not be bothered by head or wear.

I have a $200+ IR handheld unit that still does not work on molten Pb, so forget it and find another method of reading the temp indirectly.

banger