IR reflective thermometer


Can I use one of there for my lead pot and casting molds? I see them for as
little as $30 or do I have to spend more? Or should I get a contact
thermometer? Or try to find my thermocouple digital one?(buried in "The
Move")
Reply to
Buerste
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I suspect the answer is "maybe". I assume you would get one with the appropriate temperature range. I use one regularly for many purposes: The quickest way to determine the room temperature in my garage is to take the temperature of the walls. It was great when trying to determine where are the heat leaks in the house. It works well when cooking (frying pan temperature), it is quite reliable in measuring the temperature of the etching bath (ferric chloride - a big advantage as you do not want to dip things into that stuff). The one area where it consistently fails is on shiny metal surfaces. For my heat transfers I use an aluminium plate and it under-reads the temp by quite a bit. However, it reads the temperature of the items *on the plate* and that for my purposes is sufficient.
I understand there are thermometers which correct for emissivity but I doubt that they will be $30.
What I am saying is that even though the thermometer my not do the job of reading the temperature of the surface of the molten lead for you accurately, there may be creative ways of getting around that problem.
Reply to
Michael Koblic
The easy way is to attach a thermocouple to the outside of the pot. I used a simple wire clamp that holds the couple to the exterior of the pot. Then fire up the pot. When the lead melts use a contact unit and compare the readings.
Reply to
Steve W.
Way too complicated for the purpose. The bimetal thermometer I use is designed for casting purposes, cost less than $20 at the time. The temp you need to know isn't the pot's surface temp, it's the internal temp. And once you get good results, remember where the rheostat position is on the electric pot control for next time. Both Lyman and RCBS retail thermometers for casting. They're stainless and won't get dissolved by hot lead. One of the easiest ways to improve bullet quality is a good thermometer. You want the lowest temp that you can get full fillout with.
Stan
Reply to
stans4
There isn't much I can add to the good answers posted already.
I have used professional equipment like the emissivity-corrected IR thermometers and multipoint thermocouple loggers.
Thermocouples read randomly low unless they are in a deep hole packed with conductive material. Strapping them to the wall under insulation doesn't always give a good reading.
Aluminum is awful to read accurately. The IR emissivity varies from below 0.1 to above 0.9 depending on oxidation, i.e. how long it's been hot. You can't tell by its appearance.
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Black heat sinks weren't so bad, a setting around 0.8 - 0.9 made the IR temperature agree fairly well with an embedded thermocouple. Notice on the chart that most dark materials like black hi-temp paint and cast iron are in that area. I'd soot the surface or spray a thin film of wood stove or barbecue paint.
My personal IR thermometer is a cheapie from Radio Shack that doesn't read hot enough for molten lead. I use it as MK suggested, to check the house insulation, and also to find a misfiring engine cylinder. Thanks for the Christmas list idea.
jsw
Reply to
Jim Wilkins
There are thermocouple probes that are intended to be immersed, and a stainless steel sheathed model could possibly be ideal for molten lead temperatures.
A bracket attached to the side of the lead pot housing with a ceramic heat insulator, could be a good way to mount the probe.
Reply to
Wild_Bill
I'd think "it depends". What's the emissivity of molten lead? What's your crucible made of? What's its emissivity?
Good Luck! Rich
Reply to
Rich Grise
====== Just my 2 cents worth, but you appear to be going overboard. People cast lead bullets for 100s of years by simply melting the lead over a fire and pouring it in the molds. What do you expect to gain by very precise temperature measurement/control of the molten lead?
Unka George (George McDuffee) .............................. The past is a foreign country; they do things differently there. L. P. Hartley (1895-1972), British author. The Go-Between, Prologue (1953).
Reply to
F. George McDuffee
That's a bit disingenuous. Real heat control starts with the kind of fire you use (propane/air, acetylene/air, MAPP/air, propane/oxygen, etc.), and our forebears were VERY cognizant of their fire's properties. A thermometer on a melting pot is just a way to recover that kind of knowledge even when using a heat source that's capable of burning the melt.
The expectation, is to gain proficiency.
(OK, so I'm a measurement junkie; my kitchen sports half a dozen thermometers and a pH meter... betcha there's other readers on this group who could match me for micrometers and verniers!)
Reply to
whit3rd
======= Again this seems overly complex if you are melting lead and lead alloy. A simple stove type natural gas or lp burner or electrical hot plate is all that is required.
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if you want/need a purpose built lead melter see
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?pageNum=1&tabId=1&categoryId=8660&categoryString=9315***685*** If you shop locally and hit the second hand stores you can do much better on the prices. I just grabbed the first items I found on the web.
Unka George (George McDuffee) .............................. The past is a foreign country; they do things differently there. L. P. Hartley (1895-1972), British author. The Go-Between, Prologue (1953).
Reply to
F. George McDuffee
Reproducibility. The idea is to make the same product every time by controlling all the variables and have the highest productivity per hour of good parts. Then, be able to exactly reproduce those conditions at any time in the future. Sorry, it's in my nature.
Reply to
Buerste
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I have a bottom-pour 20# pot and a bunch of 6 cavity molds. It's easy to make crap parts in large numbers.
Reply to
Buerste
On Mon, 14 Dec 2009 20:34:14 -0500, the infamous "Buerste" scrawled the following:
I have a pyrometer floating around here somewhere. I think the limit is 800F, so it may be in your range.
-- Every day above ground is a Good Day(tm). -----------
Reply to
Larry Jaques
For my HVAC work, I put a piece of electric tape on the shiny metal I want to read. That isn't useful information when you want to read molten lead, though. Out of the tape's useful temp range. And tape doesn't stick very well to liquids.
Reply to
Stormin Mormon
ews: snipped-for-privacy@4ax.com...
Exactly, with each mold there's a small range of temperatures with a given alloy that you'll get good results. When things go well, most of my bullets are within .5 gr of each other. The others get remelted. The cheap bimetal thermometer will be good enough, save your bucks for a digital scale to weigh them afterwards. You'll be hard-put, though, to get good results with a bottom-pour pot and gang molds in my experience, get a fairly large ladle to pour from. Bottom- pour pots just don't flow fast enough. If you gotta use one that way, put some charcoal over the top to cut down vapors. Latest Handloader mag has a lot of myth-busting about casting in it.
Stan
Reply to
stans4
Exactly, with each mold there's a small range of temperatures with a given alloy that you'll get good results. When things go well, most of my bullets are within .5 gr of each other. The others get remelted. The cheap bimetal thermometer will be good enough, save your bucks for a digital scale to weigh them afterwards. You'll be hard-put, though, to get good results with a bottom-pour pot and gang molds in my experience, get a fairly large ladle to pour from. Bottom- pour pots just don't flow fast enough. If you gotta use one that way, put some charcoal over the top to cut down vapors. Latest Handloader mag has a lot of myth-busting about casting in it.
Stan
Thanks! I do have a pot and ladle too. I can fill all 6 in about 12 seconds with the bottom pour. It would be cool to have two spigots!
Reply to
Buerste
Send it.
Reply to
Buerste
I'm not currently casting due to a lack of lead. I use an immersion probe and a Omega temp controller with a relay to control my lead pot.
I have a feeling thata IR thermometer would give you a reference value. Both on the top of melt and molds.
That might be numbers that ties to nothing else but works for you in finding a sweet spot in casting.
I have both but when I get back in action, casting wise, I'll look up this thread and add what I learn.
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
I put an IR thermometer on my Christmas list, suggesting an Extech 42512. Does anyone have experience with them or know of a cheaper one that will read to 1600F or 900C for heat treating steel?
jsw
Reply to
Jim Wilkins
I'd like a 2K F version myself. Much the same - I melt metal...
I have used with comparison matches an Extech 'Amp-probe' like jaw current meeter. It was a hall effect unit and was tested by a large company and was shown to be a good bargain and ample for the work intended.
I have a 1000 amp HP clamp - but I don't need that often :-)
Martin
Jim Wilk> I put an IR thermometer on my Christmas list, suggesting an Extech
Reply to
Martin H. Eastburn

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