Laser Thermometer Question

[Mike W1]

I've long envied my mechanic buddy his SnapOn laser thermometer but couldn't quite see enough need to spring for one with my limited needs. But recently purchased one from Harbor Freight with a good discount. I don't expect it will be dead on accurate and have read enough comments to know I'm not going to get a reading off a shiny lead melt.

However while casting some 9mm's yesterday I tried taking some readings of my mould blocks and handles. Don't remember actual temps but am thinking they were in the lower end of the 200 degree range. Being my casting thermometer is showing the melt at between 650-700 and I'm getting consistently good bullets I was quite surprised those readings were not a lot higher.

My question would be is this an expected temperature range for mould blocks or would they actually be quite a bit higher?

Also any idea of what I could check with the thing to get some idea of how accurate it actually is?

[Sonnypie]

Don't know the answer to Q#1. Mine run hot enough to get really uncomfortable through a heavy welding glove PDQ.
And I don't have my NOE thermometer yet.

Q#2 - If you have an oven thermometer you could compare it to it's reading. Put it in the oven and heat it up. Then shoot the thermometer and compare the results.
It is a Po-man's way of a comparitory reeding.
Remember the oven will lose heat fast the second you open it. So Jack be ready, Jack be quick, Jack hit that thermometer really quick! (With the beam Son, with the beam.)
(You might find Mama's meat or candy thermometer in a drawer and sneek it away, too. Do so at your own peril though...) [smilie=1:

With an oven, you have the oven setting, the oven thermometer, and your Fancy Dan temperature shooter as well, for comparisons.
Sounds very cool to me. (In a hot way...)

BTW, couldn't you shoot the edge of the lead at the furnace wall and get a reading?
(Reason being, my little furnace wall is anything BUT shiney...)

Which one did you get?
Flex Shaft? (http://www.harborfreight.com/flex-shaft-infrared-thermometer-94233.html) Or Shoot-a-dot? (http://www.harborfreight.com/non-contact-laser-thermometer-96451.html)

[JSnover]

Don't be surprised if the mold temps are lower, especially if your blocks are aluminum and you've already dropped the boolit. Try shooting the mold as soon as the cavity is filled.

[Mike W1]

Which one did you get?
Flex Shaft? Or Shoot-a-dot?

Well it's a chinese made thing marked CEN-TECH Infrared Thermometer and now you know all I know about it. Actually had my outboard motors thermostat in mind when I bought it but it's still at my son's in northern MN so have not tried it out on that just yet.

My moulds are all Lyman, this one being new a month or so back so I believe they're some form of steel of late.

I just guessed a block would run quite a bit hotter than 200+ hence the question.

[JSnover]

I've never used a thermometer of any type to check mold temp. It needs to be up there but not necessarily near the melt temp. You'll know when your mold temp is too close. It'll take forever for the sprue to harden and you'll get size/weight variations. Run it good and hot for a while and check it when the sprue is still wet.

[Sonnypie]

Which one did you get?
Flex Shaft? Or Shoot-a-dot?

Well it's a chinese made thing marked CEN-TECH Infrared Thermometer and now you know all I know about it. Actually had my outboard motors thermostat in mind when I bought it but it's still at my son's in northern MN so have not tried it out on that just yet.

My moulds are all Lyman, this one being new a month or so back so I believe they're some form of steel of late.

I just guessed a block would run quite a bit hotter than 200+ hence the question.

Mike,
I just rechecked the links and they are both Cen-Tech. No matter, just curious.
My thought (short as it might be...) was that the flex shaft type could be set up (mounted) and then used as a push to test sort of arrangement.
It's anchored but aimed at what you want to monitor. Touch the read button and see what it's doing. The unit could be a ways away from your actual operation so it stayed cool, but gave you reference reads as you cast.

Kind of like a dash mount (http://www.amazon.com/Garmin-Vehicle-Suction-Cup-Mount/dp/B000NW12C0/ref=sr_1_7?ie=UTF8&qid=1317245935&sr=8-7) for a hand-held GPS... sort of idea. Or a fish finder. :-? For example.
(Clarification: I have my Lee Pro 4-20 furnace mounted to an aluminum tray and bolted down so it is solid and secure. So I could see something like an infrared thermometer being aimed at what I want to get a read on.)

We use to have different instruments at work for non-contact temperature, RPM, and recording for testing and checking things.
I kind of miss being able to borrow some of that stuff overnight to check things. It was a nice perk.

You can check all sorts of things with a non-contact thermometer. They are a nice tool.
Enjoy!

[Jeffrey]

Water / ice mix is 32*F, 0*C. Boiling water is 212*F, 100*C at sea level. Any thermometer can be calibrated or checked using these two easy to make substances. In the event of 'too shiney' surface use black electrical tape to get a reading on. Cover bowl of spoon with tape, insert spoon in water, scan spoon. Try aiming the thermometer at a clear sky - well below freezing. Clouds will give cloud temperature. Fun to play with.

[uscra112]

Before I retired from Zeiss, at least 2-3 times a year I had to engineer systems that would measure the exact temperature of machined parts prior to measuring their dimensions. (Engine blocks, heads, etc. in Big 3 auto plants.) So I've done more than my share of study of temperature measurement methods. Let me say categorically that these non-contact "laser" measurement systems are almost worthless. They measure infrared radiation from the target, and that radiation varies wildly with what is called the "emissivity" of the surface. The industrial suppliers of these things claimed that they could tell me a temperature within 2-3 percent of displayed value, IF we sent a large number of samples to them so they could measure the emissivity and calibrate their sensors. Any time a sensor required replacement, they had to go through the whole rigamarole again. Any time the surface finish changed, ditto.

Without calibration, and given unknown surfaces, they wouldn't guarantee accuracy to better than 25% of the displayed value! And that's industrial grade equipment costing thousands of $$. Bottom line, if you calibrate a Harbor Freight instrument against an accurate contact thermometer, you may be with 5% for the exact object you calibrated for. Any other object, you can be wildly off.

BTW the laser has nothing to do with the measurement process. It's just an aiming aid.

Best method is a low-mass thermocouple or RTD device, (thermistor). These are not expensive. Some under-$100 Volt-Ohm-Meters come with a thermocouple probe. I have had two of these, and they worked pretty well. I've never stuck one into melted lead, but there are versions that are encapsulated in ceramic which I would.

[Mike W1]

Without calibration, and given unknown surfaces, they wouldn't guarantee accuracy to better than 25% of the displayed value! And that's industrial grade equipment costing thousands of $$. Bottom line, if you calibrate a Harbor Freight instrument against an accurate contact thermometer, you may be with 5% for the exact object you calibrated for. Any other object, you can be wildly off.

BTW the laser has nothing to do with the measurement process. It's just an aiming aid.

Best method is a low-mass thermocouple or RTD device, (thermistor). These are not expensive. Some under-$100 Volt-Ohm-Meters come with a thermocouple probe. I have had two of these, and they worked pretty well. I've never stuck one into melted lead, but there are versions that are encapsulated in ceramic which I would.

Interesting. Kind of wondered about these things, seemed a little too good to be true so to speak. Checked it this morning against my buddies rig and they're close. And I had no idea that the laser was strictly for aiming either.

Thought it kind of funny that a mould casting good bullets with 650-700 degree lead poured in it was only measuring somewhere in the 250 eg. range. Now I strongly suspect that the mould was likely a lot hotter than that!

But I definitely don't need another toy right now so I'll skip the RTD device you mentioned.

[uscra112]

The idea of mounting some sort of IR sensor where you could wave the mold past it as you work is interesting. It wouldn't require calibration of the instrument, only that it repeats fairly well. Keep a watch on the thing, and learn what it displays when the mold is working well. It matters not whether it says 400 degrees or 50.

Until, that is, you try to tell somebody else what your best temperature is. THEN you have to have an instrument that's calibrated to a standard that the other guy can match HIS instrument to, or his results will be different, maybe wildly so.