View Full Version : digital infrared temp scanner?

03-12-2011, 10:52 AM
Has anyone tried any of those handheld temp scanners to check the heat of their lead melt?

I don't have a particular one in mind, or even know if they will read high enough to monitor a lead pot.

Just checking to see what others have discovered before I get too distracted!

03-12-2011, 11:50 AM
I've been wanting to get one to measure my mold temp periodically. Is it necessary? Heck no, but I'm a tool guy and I think it'd be cool to know the temp of the mold when I'm dropping "perfect boolits."

03-13-2011, 09:47 AM
again do to the reflectivity of the shiney lead you will not get a accurate reading. you might get close if you float a piece of steel on it but it's surface temp.

This would depend on the wave bands of the IR sensor (wave band and single or dual band) and the surface emissivity and temperature. What an IR thermometer is tying to measure is what is the peak radiation wave length emmited by a surface. In general the peak of the radiation occurs at the same wave length independent of surface material, for example 500 degree surfaces regardless of the emissivity of the material will have the same peak wave length. So the issue is how well the thermometer can estimate what the peak wavelength is.

You are correct you only get the temperaturee of the surface but it is the surface of a liquid metal, the gradient in the pot may not be great.

I am still looking for someone to report a comparison between a conventinal lead pot thermometer and an IR one in a bullet casting role, the time responce might be the more significant difference in the two types of thermometers.

03-13-2011, 12:22 PM
I have one from Habor freight I use it to measure temp of molds i am pre heating. i use a regular thermometer for lead pot/

03-13-2011, 05:28 PM

So far you are the only person who so far has said they have both types of thermometer. If you would take a few minutes the next time you are ready to cast some bullets and make readings with both thermometers and post the results it might settle or at least provide some insight to the usability of a IR unit. The conventional thermometer is probably usable hands free which would be one facet, the IR thermometer has a response time of less then a second while the conventional unit responds in 10 seconds or so.

Walter Laich
03-13-2011, 07:23 PM
When I tried my IR thermometer on the lead in the pot I got a reading that was several hundred degrees lower than the conventinal one. I'll have to try it on the mold right after pouring lead into it to see how that works out.

mold maker
03-13-2011, 08:05 PM
I have a 20 year old Lyman, and one of HFs IR thermometers. In the pot, the measurements are within 25-35 degrees. Since the Lyman has seen long use and abuse, that may be the reason for the difference. Both require a min. of 700 degree to avoid spout freeze with the Lyman pot.
At 800,(both therm.) pure lead gets the rainbow effect, and produces oxides fast.
That follows pretty much what I have read to expect. I doubt that any of the conventual themometers are closer than +/- 10 degrees, and that is awfully close to what I am experiencing.

03-13-2011, 08:11 PM
Go with the probe type for accurate temp ... The infrared will show lower than actual temps on a shiny surface .... It will work on a bullet mold if it is painted flat black with bbq paint ...

03-13-2011, 09:37 PM
Just an FYI, the IR thermometers do not give accurate readings on ANY shiny surfaces, liquid or solid. I had a job at work a month or so ago that required preheating the parts to a specific temperature before welding. The parts were machined, and therefore had shiny surfaces. The guys were using an IR themometer to check the parts and couldn't understand why a 400 degree oven wouldn't heat parts to 250 degrees. So I explained this to them, they looked at me like I just landed from Mars especially after I explained how I knew this (from Cast Boolits). So I proved it by putting a piece of masking tape over the part then reading the temp with the IR thermometer, all of a sudden we have 430 degree parts! So the surface finish of whatever you are trying to measure the temperature of needs to be dull, dark, matte, etc.


03-14-2011, 09:38 AM
When I tried my IR thermometer on the lead in the pot I got a reading that was several hundred degrees lower than the conventinal one. I'll have to try it on the mold right after pouring lead into it to see how that works out.

Try a measurment of the pot wall just above the liquid metal level

03-16-2011, 04:53 PM

This is a bit too absolute a statement, an IR thermometer may (or even probably) not make an accurate measurement of a "shiny surface" because it doesn't "see" the surface you intend to measure but rather something in the surrounding enviorment being reflected to the IR thermometer. At the same time something can appear dull, dark, etc in the visable spectrum and be bright and reflective in the IR black anodized aluminum is highly reflective (white) at some near-IR wavelengths. Gold is used for mirrors for longer wave length IR applications because if is more reflective then the aluminum or silver mirror coatings at those wavelengths if I remember correctly.

With an IR thermometer making the measurement as close to perpendicular to the surface as possible, will reduce the potential for the shiny surface effect you describe although it may not eliminate the effect.

The regular casting thermometer may work easier for liquid alloy but for example heat treating bullets the IR thermometer may work better.