Newbie with a question...Thermocouple VS Thermometer

[krw101]

OK, So this has been over a year long journey for me to start to cast. I was reading on here and doing a lot of research trying to figure out what all I needed. In fact I was reading "From Ingot to Target" when in the hospital waiting for my wife to be discharged after my son was born(c-section) last February. Well you can guess how much time I had to get anything done after that although I have been able to round things up this whole last year and am ready to start putting some of it together.

Now the question, I'm making a pot and at some point plan on a PID. Till I get a PID set up I was thinking of placing my thermocouple as I would but just pick up a cheap digital temperature display for now. I don't see why this wouldn't work and am wondering why I haven't stumbled on threads of others doing this. Seams like a good idea. Thermometer $30, Thermocouple and display $15. Am I missing something?

Thanks for any help,
Ken

[Frozone]

yup, try to find a cheap digital display that reads to 700º F or more.
The normal ones top out around 140º.

Here (http://www.aliexpress.com/store/product/Digital-DC-Temperature-Meter-for-K-Type-EGT-Probe-F/508924_500757343.html) is the only cheap one I have found so far.
And it needs a lot of supporting components.
I also have never seen a Working example yet - out of three tries.

[dikman]

Coincidentally, I've been searching ebay for thermocouples, to see what's available, and I came across a few places that sell assorted thermocouples and digital "readers" to plug them in to (which I guess is what you're talking about). They aren't very expensive, but do require the t/c to be fitted with a two pin plug (not spade lugs).

Just search on "thermocouple).

[krw101]

Coincidentally, I've been searching ebay for thermocouples, to see what's available, and I came across a few places that sell assorted thermocouples and digital "readers" to plug them in to (which I guess is what you're talking about). They aren't very expensive, but do require the t/c to be fitted with a two pin plug (not spade lugs).

Just search on "thermocouple).

Yep, that's what got me thinking... Stumbled on them, they look like digital voltmeters, just they display in temperature.

I may just dive in with a PID, haven't decided yet, just was wondering why no was was using these.

[el34]

A PID is so much more than a temperature indicator. It controls the temp of your pot, a very good thing.
I know you already know that, it's just worth stressing. Until you go PID how will the pot you're making be controlled?

[wv109323]

I would not spend the $30.00 on a thermometer and no control for your pot. I would spend $80-90 bucks for the PID and be finished. Keep us posted on the build of your pot . I am interested.

[el34]

I would not spend the $30.00 on a thermometer and no control for your pot. I would spend $80-90 bucks for the PID and be finished. Keep us posted on the build of your pot . I am interested.

Copy that.

[krw101]

Well you guys made me decide to just go for the PID... I might get the digital readout at some point if for nothing else so I can double check the PID.
For those interested, I'm making my pot out of the bottom of a old CO2 fire extinguisher(free) with a 1750watt band clamp(cheap online). I got an old oven(free, neighbor remodel) that I'll pull a knob off of to regulate it so I can run it with no PID if I so desire. I will try to draw it up so I can post it and listen to everyone tell me all the things I have wrong, figure that it's a lot easier to fix that way.

[GLL]

A couple years before I got my PID units from Frozone I bought this digital thermometer on sale from Harbor Freight for just over $20. It has been VERY accurate !
The K-type thermocouple goes to 1000 degrees F .

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

Jerry

[krw101]

That's exactly the type of thing I was thinking! Too bad I can't find that on their web page.

[el34]

Well you guys made me decide to just go for the PID...

Good decision. Pot temp is an important variable in casting boolits consistently. A PID will make that happen, all you do is discover the happy temp for each mold.

Then comes controlling the mold temp, the other important variable. Sooner or later that will be automated too, better than "get your casting cycle timed just right so the mold cools off just right".