Checking PID & Lead Thermometer Calibration?

[Mike W1]

Got to play a bit with my new PID controller setup today and looks like it'll be a dandy. One or the other is definitely off so my plan is to take a glass of crushed ice and water to check the thermo couple. The lead thermometer is scaled from 200 to 1000 degrees so figure I'll boil some water on my smelter furnace and check em' both that way. Only way I can think of to do it.

Should that work?????

[CGT80]

That is the route I took. Afterwards, check the PID readout vs. your lead thermometer and see how close they are at the temp of melted lead. The PID doesn't have to be spot on to work well, although I want mine to be accurate as well. Seeing the number 650 vs. 670 on your PID won't matter as long as you know what value you want for the casting you are doing and as long as it keeps it at that number. If you get both devices to show the same number while casting, you can use either to later check your melt and you will know if one has varied. If they are different you would have to record the difference and hope it is the same at various temperatures. My lead is scrap and I use various molds so I don't always use the same temp, but I do want it to stay at one temp when I figure out how how I need it to be. The next batch of lead might be a little different. The factory lee temp control was about as good a me just plugging the cord in when the pot got cool. The lower the lead level the hotter it would get, even on just one setting. The PID made a huge difference. I'm still new to this, so others may have even better info.

[theperfessor]

I did the crushed ice and boiling water routine with mine also. I have some scrap roof sheathing that is pretty much pure lead. My PID read 623F when it melted; pure melts at 621F. I figure that's close enough. Can you get any pure lead?

[Mike W1]

Did the ice and boiling water today and my readings were close with the PID. 35 and 208 F. Doesn't need to be any closer than that! However I did find my thermometer reads around 50 degrees low. It's got the nut on the back so think I'll give it a whirl adjusting it with boiling water and try to get it a little closer. Cast a few 9mm's today and I'm really impressed with the new controller. Learned a few things too!

[el34]

Curious- what kind of wire did you use inside your box to connect the TC connector to the PID controller?

[Mike W1]

Curious- what kind of wire did you use inside your box to connect the TC connector to the PID controller?

Used a section of the braided cable of the TC from the socket to the PID. Power into the unit was 14 ga. and power out also 14 ga. to the power outlet from the output of the SSR. All other connections were made with hookup wire and I'd guess that might be 16 or 18. Wasn't marked so I don't really know. Used 2@ 8 lug terminal strips, one for Line and one for Common. Each strip was jumpered on the bottom with 14 ga. solid wire. Spade lugs crimped and soldered on ALL wires. Probably overkill but works anyhow.

That braided stuff on the TC about drove me nuts! Never figured out how to unbraid the stuff.

[Frozone]

.......That braided stuff on the TC about drove me nuts! Never figured out how to unbraid the stuff.

Steal one your wife's large sewing needles. It'll pick it apart.

after you get enough undone you can trim it but with difficulty, it doesn't cut clean.
Then use heatshrink shrink tubing to hold the cut part in place and prevent more unraveling.

BTW TheProfessor's method is about the best way to check. Mechanical thermometers are often inaccurate at the ends of their scale.

[reddoggm]

That braided stuff on the TC about drove me nuts! Never figured out how to unbraid the stuff.[/QUOTE]

This braided wire your talking about is that SRML wire (silicone/rubber /motor lead) looks like the stuff in the old toaster ?

[Mike W1]

I did get the wire braid cut back eventually but didn't find it to be fun! Did the heat shrink thing as suggested in the instructions. Never thought about trying a needle though. Don't have any PURE lead to check things with and that's not worth doing for me. I was more concerned with which temperature reading was nuts and boiling water and ice showed me it was the mechanical one that was off. A couple degrees on the TC reading isn't that important.

el34 - did you think I had used something else wire-wise to hook up the socket for the TC probe? Wondered why you'd asked.

[el34]

el34 - did you think I had used something else wire-wise to hook up the socket for the TC probe? Wondered why you'd asked.

Before I built mine I hooked up the controller, TC, SSR, and Lee pot with it all laying out on my kitchen counter to do a "sanity check" before assembling everything. The PID stayed deadnuts accurate over a few hours of test time. The TC was directly connected to the PID.

Then when I put it all together in my chassis I didn't put enough credence into the rule to use TC-compatible wire and connectors for all TC connections. I used 'regular' wire between my panel-mount TC connector to the controller. What I found was that the controlled temp would be very accurate initially but over about 15 minutes it would become increasingly inaccurate, finally settling at about 40F off. My fault for ignoring the effects of using non-TC wire/connectors inside the cabinet. Their metal junctions produced their own temp-related microvoltage, just like a TC does, but at a different value and would alter the TC voltage before it got to the controller. I replaced the wire with a piece I had cut off of the TC but getting a true TC connector finally fixed everything.

I was checking against 2 lead thermometers that agree with each other.

Your test looked conclusive but so did mine initially, it took a while to see it drift off.

http://castboolits.gunloads.com/show...ler-lie-to-you
starting at post #17.

[Mike W1]

I had the good fortune to be able to go through PAGES of stickies before I did mine. Only thing I screwed up was after having it assembled I took a couple connections loose to get at tightening something or other up. In the process I reversed the 7 & 8 leads to the SSR. Once I caught that things worked just fine. By this time I think I've almost memorized those stickies. About 6 times through and it made sense!

Before I built mine I hooked up the controller, TC, SSR, and Lee pot with it all laying out on my kitchen counter to do a "sanity check" before assembling everything. The PID stayed deadnuts accurate over a few hours of test time. The TC was directly connected to the PID.

Then when I put it all together in my chassis I didn't put enough credence into the rule to use TC-compatible wire and connectors for all TC connections. I used 'regular' wire between my panel-mount TC connector to the controller. What I found was that the controlled temp would be very accurate initially but over about 15 minutes it would become increasingly inaccurate, finally settling at about 40F off. My fault for ignoring the effects of using non-TC wire/connectors inside the cabinet. Their metal junctions produced their own temp-related microvoltage, just like a TC does, but at a different value and would alter the TC voltage before it got to the controller. I replaced the wire with a piece I had cut off of the TC but getting a true TC connector finally fixed everything.

I was checking against 2 lead thermometers that agree with each other.

Your test looked conclusive but so did mine initially, it took a while to see it drift off.

http://castboolits.gunloads.com/show...ler-lie-to-you
starting at post #17.

[el34]

I had the good fortune to be able to go through PAGES of stickies before I did mine.

Cool, it's good to end up with more knowledge than what the immediate need requires.

[Mike W1]

I had a real good day. Got my dial thermometer to read within 7 or 8 degrees of the TC and that was at 640 deg. Close enough as I'll just use that one to keep an eye on my top feeder pot. Cast a nice little batch of 9mm's after that and am convinced I should have listened and had one of these controllers long ago.

Mild day here temperature wise but then I got my 22/45 out, set up the brass catcher and send some small lead downrange. From the comfort of my wood heated shop with the top half of my newly converted dutch-door. From the looks of the target I need to get back into practice but at least I was warm!

[dikman]

From the comfort of my wood heated shop with the top half of my newly converted dutch-door. From the looks of the target I need to get back into practice but at least I was warm!

That sounds like an extremely civilized way of shooting .

[dpoe001]

i was told not to repair these any more just replace with new(they last for years running 24-7)i use the old ones just for thermometers