Digital Thermometers

[tomf52]

Has anybody used one of these for watching the temps in their lead pot? I think it may be a convenient tool as it would not be in the pot and thus out of the way but would give instant temp checks when needed. Sears (Craftsman) has one on sale this week that goes to 1000 degrees F for $49.99 or something like that. Anybody got any thoughts on this?

[Junior1942]

Buy it. You'll find all kinds of uses for it other than casting. I use a Lyman thermometer for casting.

[tomf52]

Junior - I know they are great for finding a miss in an engine. Just point it at each cylinder's exhaust port and the cool one is your bad cylinder. I suppose I'll find other uses for it also.

[Lone Hunter]

Hi, I'm new to casting. Are you talking about the point and shoot inferred thermometers?

I have one and it will not read off the melted lead, it will read off of the side of the cast iron pot I used for smelting. I assume it is being reflected off the lead or absorbed by it.

Has anyone had this happen?

Thanks,

Jeff

[Mouldsmith]

While this digital thermometer maybe a bit pricey for some casters here is what we use in our shop. It comes with both a bead and 6inch wand type K probe. The wand is placed into the lead pot just like the analog thermos by Lyman, RCBS etc. We use the same bracket to hold the wand as we used for the Lyman type. Over time we have found the analog thermos get out of calibration and need readjustment, digital thermos are simple to recalibrate. While the non-cantact infrared thermos work well they can be inconvienient to use.

Available online at use-enco.com Mini Thermometer with probes Model 505-3483
$104.65.

Regards,
Barry

[Snydley]

On a scale of 1-10 ,How important is it to have and use a thermometer while casting?.....I have a Lee bottom pourthat I just turn on till it melts the aloy I put in there.........Diff temps for dff alloys?

[garandsrus]

tomf52,

If you do a search on digital thermometers you will see several posts with some good information. Many people have purchased a thermometer at Harbor Freight for about $28 or so. You need to add a thermocouple that can be immersed in lead, which is another $10 or $15. They seem to work very well.

John

[Poygan]

Perhaps I'm the exception but I bought one and find that I rarely (if ever) use it. Different molds prefer different temperatures but I adjust the setting until I get good boolits. I typically cast with only one or two molds per casting session and this works for me.

[AbitNutz]

Has anyone thought of using one of those laser thermometers? Just point the beam at the lead and see what it reads? Do they go up that high?

[Junior1942]

On a scale of 1-10 ,How important is it to have and use a thermometer while casting?.....I have a Lee bottom pourthat I just turn on till it melts the aloy I put in there.........Diff temps for dff alloys?If you're smelting wheelweights a thermometer is a must-have #10 in order to cull the zinc weights.

[upperb]

Mouldsmith:

I'm looking at the infrared thermometer, too. What do you find inconvenient about them? It would seem that not having wires hanging around the pot would be a plus. Have you had the trouble Lone Hunter has experienced?

Thank you very much.

[floodgate]

AbitNutz, upperb:

The problem with those IR thermometers is that they assume you are reading from an optically dead black surface. If you point it at the the lead in the pot just after fluxing and skimming, or at a shiny aluminum set of mould blocks, the reading will be too low versus the actual temperature. But they are handy tools if used right - like to watch for overheating bearings on our "hit-'n'-miss gas engines.

floodgate

[upperb]

floodgate:

Thank you very much for the informative response.

What thermometer do you use when smelting? Would the infrared thermometer's readings likely be accurate if it is used before skimming the lead? Would I be correct in assuming that the amount of ambient light, whether incandescent or fluorescent, wouldn't make a difference?

[Mouldsmith]

upperb,

Gave a detailed response, but reply won't post so I give up. Too long to rewrite. Short of it, bought an infrared, sucked so I threw it across the fence.

[floodgate]

upperb:

I use a quality dial thermometer obtained from Bill Ferguson, "The Antimony Man", but - frankly - I go mostly by "feel"and experience over the years with my two old SAECO pots. The "gray" surface of the un-skimmed melt would give a more accurate reading, BUT, the layer may have some insulating effect, reducing the indicated temperature below that of the melt itself; certainly a layer of sawdust or litty kitter would reduce the apparent surface temperature. The wall of the pot at the "water line" should read pretty accurately, but only if the heating element heats it uniformly. The IR thermometer shouldn't be affected by the ambient lighting, which contains little or no IR component. But an immersion thermometer or a suitable thermocouple sensor and meter would be preferable, in my opinion. (And I have, and have tried, all three types for various purposes - though I do not have a really suitable thermocouple element for poking into the melt.)

floodgate

[lurch]

AbitNutz, upperb:

The problem with those IR thermometers is that they assume you are reading from an optically dead black surface. If you point it at the the lead in the pot just after fluxing and skimming, or at a shiny aluminum set of mould blocks, the reading will be too low versus the actual temperature. But they are handy tools if used right - like to watch for overheating bearings on our "hit-'n'-miss gas engines.

floodgate

Bingo. Reflective/shiny surfaces do not work well with the infrared reading thermometers. The emmissivity is way too low and they don't give off the low frequency "light" to an extent that the thermometer needs to work properly. If you want to make one work, try aiming at a spot on the inside of the crucible as close to the melt as you can. That should be "black enough" (high enough emmissivity) to make it work. Slowly scan back & forth from the melt to the crucible and you should find a hot spot. Close to the melt, the crucible should be very nearly the exact same temperature as the lead and that should be the hot spot you read. They will work, but it takes a little finesse. Another thing to consider is the beam width or measurement angle of your thermometer. Unlike a rifle scope, a narrower beam, smaller angle is better. This gives the thermometer a narrower field of view. The thermometer will most likely give an average temperature of what is in its field of view and the narrower that field is, the closer the hot spot you find will be to the melt and hence a better reading of the melt temperature.

[454PB]

I've found the infrared thermometer works well on the surface of molten alloy by throwing a penny in the pot. It will discolor to a darkness that then gives a dark dull surface for the lazer beam to read. I just use the same penny over and over.

[lurch]

I've found the infrared thermometer works well on the surface of molten alloy by throwing a penny in the pot. It will discolor to a darkness that then gives a dark dull surface for the lazer beam to read. I just use the same penny over and over.

Not to be overly anal, but the laser is not really reading anything. For those units that have one, it is only an indication of where the thermometer is looking, and is only really showing you where it is looking at some specified distance away. The penny trick is a good idea and should work just fine, though all recent ones are some kind of pot metal (...maybe Zn...) with a copper wash? Not sure I want that in my pot, but something similar would be just as good - scrap of HRS, old copper penny, hunk of brass (flat)... Neat idea...

[Mouldsmith]

upperb,

My apolgies for my wisea$$ earlier response, I again tried to post my earlier appraisial, again my message won't post. Don't buy a non-contact your better off with a "meat-meter" or imersable wand digital, and no, the wires are not a problem.

I'm beginning to beleive the forum message gods hate me:<(.

[Snydley]

Looks like I need a Thermometer.....

[schutzen]

The infrared/laser thermometer is an excellent idea. We use them at work for a multitude of diagnostic checks. However, I have had poor luck with Sears Craftsman tools. Not the hand tools, but anthing that is electrical or electronic. I have a year old Craftsman battery charger in my shop. I used it 5 times and it is toast. Did I misuse it? I don't think so, my "cheap" old Schumacher charger on lasted 17 years. My daughter gave me a Craftsman Laser Level for my birthday. I used it twice. The laser is fine, but the sprit fluid has evaporated/drained from the leveling vials. No, I didn't drop it and it was stored in the case. Even it they replace them "free", it still takes time to replace something that should have been made correctly in the first place.

Check with NAPA for an infrared thermometer, they had them on sale for $49.95 last month. I have had good luck with their tools.

Just my two cents worth.

[upperb]

Again, thanks to all of you for your thoughts and advice.

Mouldsmith: No need for apologies. I type with 2 fingers (sometimes 3) and more than once have lost a document it took me a half-hour to type! I know the feeling!

[AZ-Stew]

Two items:

The Harbor Freight thermocouple thermometer probe will work for immersion in the pot. You gotta bend the wires a bit to get it to stay in one place, but I guess what I really should do is make a little metal clip for it so it doesn't move. It's interesting to watch the display as you move the thremocouple around to different spots in the pot. Which brings me to item 2...

Taking a reading from the top of the pot will not tell you what the temp is at the bottom (for bottom-pour casters) or in the middle (for the dippers). The temperature can be (if I recall correctly) about 20F different from the top of the melt in my Lee 20# to the bottom, nearer to where the heating element is. The heating element on my pot is about an inch above the bottom and the melt temp is understandably a few degrees hotter there on the sides of the pot than it is at the center bottom of the pot. Point is, the IR thermo won't tell you what the temp is at the point you're drawing your alloy from in the pot. Ya gotsta get the thermo down into the mix.

Regards,

Stew

[Sundogg1911]

AZ-Stew,
There are only 2 issues I have with the Lee pots. The first one is the dreaded drip, drip drip. which I can live with, the other is as the alloy lowers in the pot, i'm always backing off the temp. The heating element is on the bottom. even though I am always stirring, I wonder if i'm getting an accurate reading with my Lyman thermometer. For the price though, i'll live with these few issues. :-)

[tomf52]

Floodgate - When using your infared on this freshly skimmed surface of the pot were you holding the thermometer 90 deg perpendicular to the surface? If held at an angle the refectivity would be compromised.

[floodgate]

tomf52:

No, it was at an angle; I'll give it a try held vertically next time I've got a pot-full all melted and skimmed, and comare it with the thermometer.

floodgate

[AZ-Stew]

Sundog1911,

My Lee 20# started its life relatively drip-free, but after a few sessions it started leaking (I think my 10# leaked from day 1). I suspect it's due to alloy impurities accumulating around the valve seat. Someone on this list mentioned improving the valve seat by putting valve grinding compound on the valve rod and running it in a drill in the pot spout to increase the valve seat area. I may try it. Can't hurt.

As to the temperature swings, this issue bothers me a bit, as well. Mine swings pretty widely. I'm considering the mod someone else posted here to add a digital temperature control to the pot. A thermocouple is fixtured to the bottom center of the pot and connected to the control unit (PID?) which, in turn, controls a relay that connects/disconnects the power to the heating element. It's a far more precise arrangement than the stock mechanical thermostat, and can be done for about $75, making a well controlled pot for a price that is still far below the other manufacturers' offerings. I may take a crack at it, as well.

Regards,

Stew

[vmt_hntr]

Before I retired, I acquired 2 digital heat controllers(will go well beyond 1000 degrees F) and 2 thermocouples that were used for the solder pots there for tinning lead wires for transformers.(being an electrician, it didn't hurt a thing that I also maintained the solder pots as well) The name on theses units was Barber-Colman...big on heat controllers...and quite pricey($500 each)...was headed for the scrap heap or auction, so my buddies in calibration department fixed me up after one operation we had went south. Boy, it sure works swell for my Lyman 20# pot....the original controller didn't last very long. No tellin' how long they will last, but have been going strong for 6 years now on the original set-up...not had to use the back-up set. The thermocouple is directly in the melt held by a bracket I made that mounts off to the side of the flat surface surrounding the pot. The 'couple is then plugged into the control box that holds the control relay and digital thermometer that supplies power to the heat element which also plugs into the control box. I can keep my pot/melt temperature within 10 degrees of what I need for consistent casting. The weak link I have found is the terminals where the incoming wire and heat element join. Seems to burn that wire in two every so often(it's an easy fix). I know not every one can acquire things like I have, but being in the right place at the right time goes a long way. Happy casting....Bob in Indiana

[Sundogg1911]

vmt hntr,
I'm looking into doing this (Since the company I work for used to be part of Barber Colman) ;-) I know we have some of these units back in the test/repairs dept.
I work more in the business end of the company, not the technical side, but I have a few friends there trying to hook me up with the parts that I need.
this would make the Lee pot very usuable, instead of always using the pot on the master caster, and locking down the mold carrier. The slight dripping I can live with. ;-)