PID placement of sensor

[bazzer485]

I carefully crimped my k type bare thermocouple with a copper crimp and put it under the spout nut against the lead pot, it was bolted very securely. What I find is the temperature at that point rises very rapidly when the valve is open pouring lead. Sometimes more than twenty degrees. What it tells me is this is a poor place to put the sensor. So I’ve ordered a replacement which I will put in the molten lead to , hopefully get a more accurate reading.

Barry

[Hairy Dawg]

I made a clamp for mine that holds it 1/2" from the side wall, and 1/2" from the bottom. I get very stable & repeatable readings.

[Mike W1]

I made a clamp for mine that holds it 1/2" from the side wall, and 1/2" from the bottom. I get very stable & repeatable readings.

That seems to be the way to go and the way mine are also.

[jsizemore]

I stick the probe in the liquid lead. When I finish a casting session I pull the probe out of the remaining lead so I can use the PID in another pot. I know, you only have one pot and one alloy. I was the same way. I'm down to 5 pots now having got rid of 2. Some deals are to good to pass up.

[RydForLyf]

Mine is in the pot as well. It gets in the way at times, but gives best actual measurement.

[Hairy Dawg]

I stick the probe in the liquid lead. When I finish a casting session I pull the probe out of the remaining lead so I can use the PID in another pot. I know, you only have one pot and one alloy. I was the same way. I'm down to 5 pots now having got rid of 2. Some deals are to good to pass up.

I use my PID for other uses as well. My thermocouple has a plug on the other end. Each thermocouple is hard mounted to whatever appliance it goes with, whether it be my second pot, mold oven, or powder coat oven.

[44magLeo]

I have a col of copper wire on the edge of my pot. The coil is big enough to slip the probe into. The mount holds the probe about a 1/2 inch away from the bottom and side next to the flow rod above the spout. This way I get the temp very close to where the lead comes out of the pot.
Leo

[bazzer485]

I have a col of copper wire on the edge of my pot. The coil is big enough to slip the probe into. The mount holds the probe about a 1/2 inch away from the bottom and side next to the flow rod above the spout. This way I get the temp very close to where the lead comes out of the pot.
Leo

Leo. Yes it’s obvious for whatever reason the temp measured outside the pot at the nozzle is not the same as the lead temperature. So the probe in the lead next to the output valve is the place to put it. I like the idea of the copper wire
Barry

[Mal Paso]

Leo. Yes it’s obvious for whatever reason the temp measured outside the pot at the nozzle is not the same as the lead temperature. So the probe in the lead next to the output valve is the place to put it. I like the idea of the copper wire
Barry

Thermal Drain. Auber has a good FAQ https://www.auberins.com/index.php?main_page=page&id=6 I silver brazed a thermocouple through the bottom of a pot with just the tip inside. It was erratic and off temp until I changed the probe so it was 5/8 inside the pot and that fixed it.

[Conditor22]

A friend did this and I'm planning on changing my PID thermocouple location to under the pot using a
Non-Insulated Ring Lugs Crimp Cable Connector clamped on tothe end of a short thermocouple and clamped around the pour spout of my 4-20 with the existing nut.

One less thing to get in the way of fluxing AND the spout is where you want the certain temperature

https://www.amazon.com/KeeYees-Barre...s%2C227&sr=8-8

[Drew P]

My TC was a threaded end 1/4-20 so I drilled the pot bottom 1/4” and bolted it in with a stainless acorn nut. Sealed and protected works perfect.

[RydForLyf]

A friend did this and I'm planning on changing my PID thermocouple location to under the pot using a
Non-Insulated Ring Lugs Crimp Cable Connector clamped on tothe end of a short thermocouple and clamped around the pour spout of my 4-20 with the existing nut.

One less thing to get in the way of fluxing AND the spout is where you want the certain temperature

https://www.amazon.com/KeeYees-Barre...s%2C227&sr=8-8

If you are using the PID to control the heater, you want it to measure the mean temperature of the lead being heated. The nozzle cools off when lead isn’t flowing and this will trigger the PID to heat the lead when it isn’t really needed. The bouncing up and down of the nozzle temperature will undermine the consistency you can get with a PID with a probe measuring real alloy temp.

[bazzer485]

If you are using the PID to control the heater, you want it to measure the mean temperature of the lead being heated. The nozzle cools off when lead isn’t flowing and this will trigger the PID to heat the lead when it isn’t really needed. The bouncing up and down of the nozzle temperature will undermine the consistency you can get with a PID with a probe measuring real alloy temp.

Some people just don’t read the thread so just don’t get it.

[Dapaki]

I have been battling this phenomenon too, dropping the thermocouple in the pot sure helps a lot but depending on its location in the pot, I get temp swings too. I think the only answer is to run two probes, one on the bottom center of the pot (outside) and one inside in the center of the pot.

[redhawk0]

I run a Lee pot. The heating element is wrapped near the bottom 1/4 of the pot....so...that is where I position the tip of the sensor about 1/2" in from the side (inside). It will fluctuate a little...but +/-5* doesn't seem to make much difference in my casts. I figure this is still more stable than running the pot without a PID unit.

redhawk

[Mike W1]

I have been battling this phenomenon too, dropping the thermocouple in the pot sure helps a lot but depending on its location in the pot, I get temp swings too. I think the only answer is to run two probes, one on the bottom center of the pot (outside) and one inside in the center of the pot.

Read what you just wrote here! How the heck are you going to put 2 inputs into a PID? That makes absolutely no sense.

[bazzer485]

Read what you just wrote here! How the heck are you going to put 2 inputs into a PID? That makes absolutely no sense.

Mike, I think a awful lot of posts here are just theory and not from actual casters etc. So I’ve given my practical results.
Bazzer
Who Dares Wins

[redhawk0]

No...Dapaki is right...I think with one inside, and one outside you would provide better regulation (this is from a Dual Input PID unit). But this isn't rocket science...a single PID input should be sufficient.

redhawk

[Dapaki]

Read what you just wrote here! How the heck are you going to put 2 inputs into a PID? That makes absolutely no sense.

Mike, they are normal parts of line temperature measurement devices, in my case it's a 1/8 DIN dual Temperature, process and strain PID controller.

[Dapaki]

Mike, I think a awful lot of posts here are just theory and not from actual casters etc. So I’ve given my practical results.
Bazzer
Who Dares Wins

Nice....