Hot Deal! Inexpensive Digital Thermometer from Harbor Freight

[AZ-Stew]

All,

I got an ad in the mail a week or so ago from Harbor Freight listing a digital thermometer at a VERY reasonable price. They have several models. Some are IR or laser, but the one that is suitable for our purposes uses a thermocouple, which is two wires of dissimilar metals welded together at one end and the other end connects to the instrument. As the junction of the two wires changes temperature, the electrical resistance changes. The thermometer converts this to a digital display of direct temperature readout. This unit is rated up to 2,000 degrees and down to some degrees (don't remember how many and the instruction sheet is out in my shop) below zero. It reads in degress F, C and Kelvin. And the price is definately right. It's on sale now for $26.99 (Reg. $36.99) until Sept 11. The model number is Cen-Tech 92242. I couldn't find it on their web site, but it may be available in a Harbor Freight store in your area. No, I don't work for them. I work for an electronics company.

I set mine up to check the temperature in my new Lee Pro 4-20 pot. It's very responsive. From room temp, it takes about 10 seconds to stabilize in molten lead alloy. Then when the thermocouple is moved around in the pot the temperature differences from center of mass to, for instance, the sides of the pot where the heating element is, takes only about a second. It will show differences of only a couple of degrees. Far more sensitive than a dial thermometer. It's supposed to be accurate to within 1 degree F over the range. I know it is right on the money at room temperature, but I don't have any way, at present, to check calibration at lead pot temperatures.

If you buy one, when you first turn it on, be sure to set it for degrees F, and to the 1 degree resolution. I thought I had killed mine when I first stuck the thermocouple in the pot. The display went blank almost immediately. The thermometer was set from the factory to 0.1 degree resolution, and the lead temp exceeded the display scale. No damage, just a worried operator until I figured out what was needed (should have read the instructions :roll: ).

The unit has auto shut-off after about 10 minutes, which is irritating if you want continuous temp monitoring. It also defaults to degrees C, instead of F, so when you turn it on you also have to set it for F. Maybe the unread instructions tell you how to set the unit to come on in degress F. I usually read instruction sheets, but I was in a hurry to do some casting and to report this nice little tool to this forum. If I come up with more info after I read the instructions, I'll post it.

Here's a photo of the unit in action with the thermocouple (white wire) in my new Lee pot with some familiar items in the photo to give you an idea of the unit's size. The bullets on the right are some of the .32 SWCs from an RCBS mould. There is a Lee ingot mould and the RCBS .32 mould showing, with the thermometer and instruction sheet at the bottom and left. Oh, yes, it also has it's own stand in the back of the unit. It's in use in the photo.

Regards,

Stew

[PatMarlin]

I say a big wooo hooo on that one Stew.. :drinks:

[PatMarlin]

I couldn't find it neither.

[AZ-Stew]

For those who are interested, I just called Harbor Freight customer service about this item. They told me it's only available in retail stores. Judging from their web site, there are plenty of stores around, so everyone should be able to find one. Amazingly, extra thermocouples are only $1.80 each. I think I'll order a couple of spares since they're the most delicate part of the instrument.

Good luck and good casting!

Stew

[Edward429451]

K type thermocouples are rated to 2000 deg.? I never knew that. I use a similar setup with a regular digital multimeter for HVAC work.

And all this time I've been casting with no lead thermometer...

I think I'll try that. I have extra thermocouples.

[kodiak1]

Too Cool but we don't have Harbor Freight stores in Canuckastan.
Home of Ice and Eskimo Pies.
Ken.

[AZ-Stew]

Sorry for the misunderstanding. The thermometer reads up to 2,000 degrees Fahrenheit and will convert to degrees Celsius and Kelvin by pressing the associated buttons on the front of the instrument. The numerical value of the Celsius and Kelvin readings will be lower than 2,000 degrees, but will be equivalent to the Fahrenheit value.

Regards,

Stew

[Edward429451]

As long as the thermistor don't melt off the end, it should be fine, which is what I was wondering about.. Thanks for the clarification.

I have a Harbor freight here locally. If anyone wants one I'd be willing to pick it up & ship it to them gratis. You would have to pre pay for unit & shipping but HF & the post office is both close so no big deal there. I drive by them constantly.

[Four Fingers of Death]

Those Chinee boys can really turn out a cheap product, and that's no Fluke :-)

No doubt they will turn up in Australia soon if they aren't here already. We don't have Harbour Freight her, but have similar stores, Toolex and Gasweld. That's cheaper than an old analogue one. MIck.

[John Boy]

Stew, for that price .... I'm gonna buy 2 of them. Never know when one might need a spare. Good excuse to buy another pot too [smilie=1:
Thanks for the Hot Deal!

[John Boy]

Stew, for that price .... I'm gonna buy 2 of them. Never know when one might need a spare. Good excuse to buy another pot too [smilie=1:
Thanks for the Hot Deal!

[Topper]

Thanks for the tip Stew;-)

[AZ-Stew]

Edward429451,

No thermistor involved. Please see this link for more info:

http://www.omega.com/prodinfo/thermocouples.html

Regards,

Stew

[PatMarlin]

Whata bout' this one:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91778

I wonder what the range is?

[dragonrider]

got no HF stores in New England.

[AZ-Stew]

PatMarlin,

I think the measuring range is too small for our work. The laser and IR thermometers carried by Harbor Freight are typically oriented to the automotive industry, for measuring engine temperatures and whatnot. I don't think they go above about 500F. You're welcome to call their 1-800 tech support line and ask them, though. If you do, please report back to us.

Dragonrider,

My sympathies. :violin: Here's your excuse to move out of Communist-held territory. :wink:

Regards,

Stew

[Edward429451]

Great link there stew. Learn something new everyday.

from what I can tell from a brief reading about the selection they have, my sheathed K type isn't the correct one. Some of the ones they have are over 200 dollars!

You obviously do not have a 200 dollar T-couple with your setup. Are you able to identify the exact one that you have? Or at least snap a close up of the probe end?

I don't want to spend more on it than a regular lead thermometer. All I need is the thermocouple.

[AZ-Stew]

Edward429451,

I have occasion in my job to deal with temperature measurement as related to semiconductor devices. Typically, the thermocouples we use appear to be little more than a wire insulated with a fabric material and a small metal bead at the end exposed outside the insulation. This is where the two wire materials are joined. The two wires are individually insulated inside the fabric sheath.

The thermocouple that comes with the Harbor Freight thermometer is similar, except it's larger than the ones we use for semiconductor temp measurements. I believe the link (above, post #13) explained that larger wires are needed for higher temperatures. Again, though, there is nothing more than a small metal bead at the business end where the wires are joined. The other end has a two-pronged plug that fits a socket on the instrument.

As far as cost, the RCBS thermometer is $39.99 from Midway (+ shipping) and the Lyman is 28.99 (+ shipping), so either way, if you buy the digital from HF you're going to save money, in addition to avoiding the issue of calibration that you'll have using a thermocouple and digital multi-meter.

Regards,

Stew

[Edward429451]

Yeah, thats prolly what I should do is just order from Midway.

My experiance with HF is that they sell some good stuff and a lot of junk. I dunno about their meters.

Let us know how yours holds up, will you?

Do you have a way to check the accuracy of the setup you have? That'd be interesting to see.

I usually get my meters calibrated once a year (usually!) I sometimes deal with some pretty high voltages, and pretty minute readings (Ohms, microamps).

[AZ-Stew]

Edward429451,

The only way I know to check the accuracy of the HF meter without additional instrumentation is to put the probe into several different hot liquids and see what temperature is displayed as the material passes from solid to liquid and vice-versa. Melt/freeze temperatures of metals are well known. I have some nearly pure tin, some nearly pure lead, some linotype and some wheel weight metal. This will give me a ballpark idea, but the best way would be to put the thermocouple into a calibrated oven. I don't think my company's lab has one that goes high enough, and I probably can't borrow it long enough to use it anyway.

For my uses, it doesn't really matter. What I want to know is relative temperature of my casting alloy. I've already found out that:

1.) The numbers on the dial of the Lee pot I'm using mean nothing. This was no surprise.

2.) I prefer to cast at the lowest temperature that will give me consistent mould fill-out. When my thermometer reads below 600F with wheel weight alloy, the bottom pour spout is about to freeze. When the indicated temperature is above 650F I have less trouble getting square corners on the bullet bases (IMPORTANT!).

3.) After weighing a few bullets last evening, the results SEEM to indicate (not enough data collected yet to confirm, but enough to make me want to investigate further) that bullets cast with my RCBS .32 SWC mould have more consistent weight when cast at the lowest practical temperature, 650 - 700F, than they do a couple hundred degrees higher. More to come on this later.

4.) The thermostat on the Lee pot has a fairly coarse potentiometer. It's difficult to make small temperature adjustments.

None of these things would be known without some means of determining relative temperature. While exact values would be nice to know, I'm not sure they're as important as knowing the temperature delta and having an idea what happens to the alloy at certain temperatures as indicated on my thermometer.

As far as durability of the HF meter, it has a warranty and, as noted earlier, I plan to get some extra thermocouples since they're cheap and they do get bent around during use. As you know, bending wires around eventually work hardens the metal and the wires break. I've bought several of their digital multi-meters and have yet to have one fail. They aren't used daily, but they always work when needed. In addition, for $5 - $9, they're hard to beat. I've been watching HF quality over the years and have been impressed with their progress.

Regards,

Stew

[Edward429451]

<without additional instrumentation>

That's what I do. I have several different meters and a couple digi thermometers and test em agains each other. Some can be recalibrated. (Nothing in lead melt range though).

I have a small Lee pot and just yesterday picked up a new/used RCBS ProMelt. I need to calibrate the dials (with a magic marker) and see whats where. I've been casting hotter & hotter but don't really have a clue what temp I'm at. Frosty fills out the mould for me. I got that 6 cav 45/70 GB mould so hot it got to the point that it stayed molten in the mould for a few!

Good info! Thanks.

[John Boy]

... there is a good probability that all the retail HF stores don't have the digital. The one here in Jersey didn't have it in their inventory database. So, ask for a Rain Check and hope you don't get one of their ...'Sorry, this item is no longer stocked by Harbor Freight.'

[LET-CA]

My local store has four of them in stock (on sale too) - Sacramento, CA

[brshooter]

To check calibration at a lower temp, insert the end of the thermocouple in boiling water= 210 degrees F or 100 degrees C. unless you live on top of some mountain or Denver.

[PatMarlin]

I'll trade a Thermometer for Eskimo Pies.. :mrgreen:

[lar45]

A thermocouple does not have a thermistor on it. The thermistor is a different device that changes resistance to changeing heat.
The thermocouple generates and electrical current by the two dissimilar metals being put into a different temperature source. It's the change in temperature from one end to the other and the difference in the two metals that creates the current.
Larger thermocouples can be used to power small devices if you have a regular heat source.

FWIW


As long as the thermistor don't melt off the end, it should be fine, which is what I was wondering about.. Thanks for the clarification.

I have a Harbor freight here locally. If anyone wants one I'd be willing to pick it up & ship it to them gratis. You would have to pre pay for unit & shipping but HF & the post office is both close so no big deal there. I drive by them constantly.

[kywoodwrkr]

Just called my my local HF store.
If I hurry, before the 12th, I'll be able to get the very last one!
That is if I buy all ten of the ones they have in stock!
Anybody need one?
I can buy and ship, up to nine that is, for the cost + tax(6%) + the postal cost only if one(or more) is needed.
DaveP

[HTRN]

Those Chinee boys can really turn out a cheap product, and that's no Fluke :-)

That actually made me giggle.


HTRN

[mattc]

patmarlin
the laser thermometer you mentioned in post #14 has a range of 4* to 518* F

[PatMarlin]

Thanks I saw that. I was at HF Yesterday and looked.

They had the other one, but I had to spend money on other stuff.. :roll:

[GP100man]

fellas before buying atemp gun let me tell you my exp. when the melt was shiney &clean my temp gun went crazy ,but always low250f to 400f. lead melts at 600f rite? when i tried to shoot out side of pot over lp burner heat tanted reading !so ibought a thermometer stuck it in the pot &now ad just heat according .

[PatMarlin]

Whatn kind of thermometer?

[Texasflyboy]

Thanks for the post on the Digital Thermometer. I ran out today and bought one at the Houston Texas store, they had about 12 in stock. It wasn't in the catalog, nor on the sale flyer. The sticker price on the shelf was $34.99 but I asked the nice gal at the register to check the price and it rang up at $26.99.

I really should have bought two...maybe I can go back tomorrow.

By the way, the unit comes with a small K type thermocouple that really wasn't useful to me for casting.

But I did manage to disassemble the little spade connector that comes with the K thermocouple and discovered that it will be really easy to retrofit my "K" type thermocouple I got from eBay to this unit. The factory K type wires are held in place with philips screws. I will make the change tomorrow and post pics before and after if anyone is interested.

Before I did that, I did just run the bare wires from my K type into the little + and - slots and it worked fine. I ran a few temperature tests and the digital HF model was within +- 1 degreee F. I ran it up to 1000F before I was satisfied. It's a nice thermometer for the money.

If you really want to trick this unit out, get a stainless shielded K type thermocouple from one of the vendors on eBay. I paid about $15 for mine. It's a K type, with a stainless steel sheath about 10" long, bent 90 degrees at 5" into a "L" shape. Works great with this unit. And you can immerse this style thermocouple into molten lead. See my other post about "Diary of a Casting Pot Construction" to see a similiar style thermocouple I used in that construction (that one was a "J" type, but made the same as the "K"s with the stainless sheath)

Thanks again for a great tip. This is a great deal for a digital thermometer for casting.

Tom in Texas

[Texasflyboy]

OK,

Here is what I did with this unit:

Here is what you get for $26.99 when it's on sale:

http://users2.ev1.net/~eastus1/a/00.jpg

Here is a peek inside the original lead housing. I was adapting the unit to use my stainless steel armored "K" type thermocouple, instead of the one that came with the unit.

http://users2.ev1.net/~eastus1/a/3.jpg

Here is what I did to adapt my K style to use the factory plugs:

http://users2.ev1.net/~eastus1/a/0.jpg

And here is the finished job:

http://users2.ev1.net/~eastus1/a/1.jpg

Took about 15 minutes to do the switch. It works great.

Tom in Texas

[garandsrus]

Hi,

I am interested in getting one of these, but was very surprised by the plastic plug. Those of you using this, do you just hold it above the pot with only the electrodes in the pot?

I thought it would be more like the Lyman thermometer that had a "submersible" shaft.

Thanks,
John

[Texasflyboy]

Sorry for the confusion. The plastic plug in the photos are the connector leads that plug into the top of the unit.

What is not shown is the working end of my "K" type armored thermocouple. The working end looks like a 1/4" stainless steel tube bent at 90 degrees.

Click the following link to see an eBay auction of the style I am talking about. It will show you a typical armored K type style:

Link to K Style Auction Photo (http://tinyurl.com/qdl92)

The stainless steel end is the end that goes into the molten lead. The bare wire ends was what I was adapting on the temperature control unit.

[garandsrus]

Texasflyboy,

Thanks! That clears it up....

John

[AZ-Stew]

garandsarus,

Take a look at the photos I posted in the original post. Click the small photo to get a larger view. The plastic plug attaches to a socket at the top of the instrument and the other end of the wire goes in the pot. It's about a yard long, so there's no worry about the plastic melting.

Regards,

Stew

[georgeld]

Buttons on lead melting????

What you guys gonna think of next??

IF I didn't already have a Lyman, that would be a good idea to look at. Store's about half a mile down the street.

Some things HF sells is worse than junk. But, other stuff is amazingly high quality.
Ten yrs or so ago I bought a 14" chop saw and used it a lot when I was doing a lot of welding and cutting steel by the ton almost daily. It lasted about five maybe six years and cost $50.

Next one I bought was a $240 Milwaukee. It's been returned for repairs three times, and needs it's fourth switch when the two yr warranty ran out. I've just been pulling the plug since then. Once I get fed up with it, will set it out in the alley and see how long it takes to take a hike away from here. And get the back up HF off the shop shelf.

Tin snips and number stamps have been soft for me. But, the sockets and wrench's are great. Fact is, I bought a set of tools to replace good stuff that was stolen from my shop trk. Then got a set of lettering stamps and was going to put my name on them. First smack and the letters were flat. Not a mark on the wrench. Next two sets turns out the same way, gave that up and got a refund and engraver and been happy since.

I've taken a lot of their things back. They'll even swap a fairly new looking tape measure it if don't feed back into the box. For a long time they hassled me over a ticket and used heat tape for them so they go blank in a few weeks. Some months ago they changed to a 'satisfaction or refund/return policy' on everything.

The part I dislike most is buying crap from China when our people are out of work. Like that cartoon Dad has on their fridge.

Guys in a Toyota says: "I can't believe Ford laid me off".

[B747]

Can the straight armored K type style as shown in the ebay link be bent
into an L shape or would that damage it?
Thanks


Sorry for the confusion. The plastic plug in the photos are the connector leads that plug into the top of the unit.

What is not shown is the working end of my "K" type armored thermocouple. The working end looks like a 1/4" stainless steel tube bent at 90 degrees.

Click the following link to see an eBay auction of the style I am talking about. It will show you a typical armored K type style:

Link to K Style Auction Photo (http://tinyurl.com/qdl92)

The stainless steel end is the end that goes into the molten lead. The bare wire ends was what I was adapting on the temperature control unit.

[garandsrus]

Hi,

I went to Harbor Freight today and the thermometer was on closeout for $20 plus 6% Mi tax. I bought three (I only need one or two) and they had another three or four at least. If anyone wants one, I would be happy to send it to you for $21.20 plus actual shipping (while supplies last!), which should be pretty cheap as it's light and small.

John

[Denver]

Hi,

I went to Harbor Freight today and the thermometer was on closeout for $20 plus 6% Mi tax. I bought three (I only need one or two) and they had another three or four at least. If anyone wants one, I would be happy to send it to you for $21.20 plus actual shipping (while supplies last!), which should be pretty cheap as it's light and small.

John

John;

Sent you an emule.

Denver :Fire: :castmine:

[Gun-adian]

John,

PM on the way.

Thanks for this.

Mike.

[garandsrus]

I have a thremometer for the first five folks that asked for one. The zip codes are:
57107
Canada V3J 4M1
48653
91106
92374

I purchased the remaining thermometers that the store had so no more are availale through me...

John

[Edward429451]

I bought one of those stainless steel probes that someone linked to for 14 bucks to the door, and robbed one of my connectors off of one of my extra thermocouples and am out testing it on my pots right now.

My little Lee pot maxes out at 960ish and setting 9 is just over 900, 8 is just over 800, and 7 is, you guessed it, just over 700 deg. Whoa. How often do you see that? I guess my Lee stat is calibrated fine.

I haven't warmed up the Pro Melt yet.

Woo Hoo, I know what my melt temp is! First time in over 30 years. (I uh, started casting young) ;>)

[Texasflyboy]

Can the straight armored K type style as shown in the ebay link be bent
into an L shape or would that damage it?
Thanks

They come pre-bent if you email the seller and ask that it be bent. I had mine bent at 90 degrees 5.5" to fit my big casting pot. You can get yours bent at any length, just email and ask.

Tom in Texas

[John Boy]

Stew and Texasflyboy ... Thanks for the posts, gents :drinks:
My 2 rain check meters finally arrived at the local HF store and picked them up.

Then, got 2 of the K Type 12" sheathed probes on ebay - $24.95 with S&H. They should be here in a couple of days and then, change out the probes and test em' out.

[garandsrus]

I have received payment from each of you ...

The zip codes are:
57107
Canada V3J 4M1
48653
91106
92374

It looks like the thermometer is a pretty well made unit.

Have fun!
John

[John Boy]

The K type 12" SS sheath probes came today. Changed out an ambient temperature probe.

Heated up a tea kettle of water and watched the 'kettle boil'. The probe read 216* F when the water was boiling. The kettle of water was at 7 ft above sea level. Spec's on the digital are (+ or -) 4 degrees... Bingo!

Threw some Pb in the cast iron pot and watched the temperature rise. Couldn't determine exactly when the lead started to melt if the thermometer was at 620 degrees because the temperature readings are increasingly slow to be displayed.

Turned the digital on and off and the temperature would not go back to the F reading ... 646 degrees. Screen kept showing a '1'. Switched to the Kelvin scale while the probe was in the melt and it read the K number immediately. Then switched to the F scale and the F temperature popped up on the screen.

With the probe in the melt and holding steady at 646-647 - hit the check button. The reading was 641. Still in the calibration range. Regular bimetal Lyman thermometers are accurate to 10 (+ or -) degrees

Also, the digital will not display xxx.1 readings with the temperature in the 600* range.

Soooo, think it is a $26 + $7 winner.

[pjh421]

Texasflyboy,

Wow! What a nice website. It sure beats the old green booklet for identifying boolits/moulds.

Paul

[jacpot]

I know this thread is a few years old, but I wanted to add this about thermocouples for those that are using one such as the Cen-Tech 92242 (which is a great Dig-therm for the price)
I deal with high temps every day at work and use infrared thermometers and the 92242 for spot checking and it holds up very well.
Since I'm a Newbie at Casting boolits, I don't have much to comment on other topics but I know this particular subject very well and wanted to add these "Bullets" for those not familiar with thermocouples.

1. a T/C (Thermocouple) is two different metals that are welded together. this "weld" point acts like a semiconductor junction and will generate a small electrical signal. this signal changes depending on the temp of the junction. the meter reads the millivolts produced at this junction and converts to a temp reading on the display.
2. T/C come in different "types" (i.e. J-type, T-type, K-type) and each has it's range of operation. T-type is typical for lower temp ranges and is less accurate at high temps, J-type is midrange with accuracy up to about700~800 C, and K type is usually good up to +1,300 C.
3. Because the "weld" is what generates the signal, be careful not to short out the leads as this will create a secondary thermo-junction and give inaccurate readings.
4. I'm not sure of the effect of Lead getting between exposed (bare) leads above the weld, but it could create a secondary junction and throw off the readings.
5. the connection terminal of most T/C are color-coded. K-type is yellow, T-type is Blue, and J-type is usually Black or sometimes Green. So be aware if you are buying a replacement T/C that you get the correct "type".

I hope this info helps

[Ozark Shiner]

I've got the exact Harbor Freight set up and it works like a champ ! Just got my stainless steel thermocouple probe last weekend.

Going to be just the thing to smelt a few hundred pounds of WW sitting in buckets in the garage.

No Zinc worries now....

[PatMarlin]

Great info there Jacpot. Thanks-

[GLL]

LOVE mine with stainless K-type ! :)

Many thanks to garandsrus back in 2006 !

Jerry

http://www.fototime.com/11E8391FEDF1E74/standard.jpg

[sdelam]

I just searched habor frieght and they dont seem to sell them anymore:cry:

[GLL]

I think that they were being discontinued in 2006 when Texasflyboy bought several !

Jerry

[sdelam]

Just checked the dates on the post. Opps

[AZ-JIM]

The model you are looking for may be discontinued, I got one for Christmas Harbor Freght/Cen-tech item no. 95670 it is an automotive multimeter with the temp function in C/F that ranges from -20 - 750C and -4 - 1382F. It came with the K-type themocouple and it was $32.08 out the door. I haven't used it yet but it looks like a nice unit.

Jim

[Four Fingers of Death]

The motorcycle mechanic in th elittle village in the hills a few miles from here uses one which he just points at the cylinders. If one is running hot or cold he know he needs to tune it, awesome bit of gear, a bit fancier than these and probably cost mega bucks.

[Willbird]

IR thermometers are not ultra expensive, I have a Craftsman multimeter that has one built in.

[arjuna70]

IR thermometers are not ultra expensive, I have a Craftsman multimeter that has one built in.

Can you use Sears Craftsman in the pot for temperature. Is it one like this:

http://www.sears.com/shc/s/p_10153_12605_03482139000P

Sorry for the dumb questions, I'm a noob and am trying to decide whether to buy the RCBS Thermometer for $50 or something like this.

[kelbro]

Can you use Sears Craftsman in the pot for temperature. Is it one like this:

http://www.sears.com/shc/s/p_10153_12605_03482139000P

Sorry for the dumb questions, I'm a noob and am trying to decide whether to buy the RCBS Thermometer for $50 or something like this.

Yes, you can. You'll need a TC (thermocouple).