New PID - Experiences

[Cast10]

Just finished my PID. Mypin TA4-SSR w/ 40amp SSR. Lee Pro 4 - 20

Did some minor testing two days ago. Running auto tune several times and I noticed;
Initially temps will overshoot/undershoot; 30-40;12-15. After several auto tunes, overshoot/undershoot was about 12-15; 2-5. Once it settles in it appears to be solid.

Now, the main issue was I cross checked temp with a tru-temp dial thermometer and a electronic thermometers. Dial thermometer was 40 or so cooler; Electronic was 20 or so cooler. I thought, well, I’ll just watch how the boolits come out and adjust.

So the next day during ‘live casting’ I set to 725 and started it up. Settled in at setpoint. Had mold on hot plate, and began pouring lead. I never looked back! Temp stayed at setpoint within 2 degrees or closer! Only sway in temp was when ‘cold’ lead was added in, and it didn’t take long to recover.

Thermometers were re-checked. Dial has the nut behind the dial and I hand tightened; it was within 10 degrees; Electronic was nearly identical; a heat gun on the pot side was spot on. Oh well, I guess I’ll believe the PID!

Takeaways;
Initially, run auto tune as many times as it takes. If it keeps overshooting/undershooting, let things cool and run again. I ran it 3-4 times before I was satisfied.
Believe the temp the PID says.
Record settings - Once done, record all settings, just in case. You can re-input if need be.
Initial overshoot is not a bad thing as long as it ‘settles in’ and holds.
Trust your judgement on temp - How the boolits come out. Adjust temp accordingly.
Find the right temp for you. 725 matches my cadence. Once after adding cold lead I began pouring at 712. Lead was not totally ‘set’ when I cut the sprue. Waited for 725 and all was fine.
Read the manual that comes with the PID. They are all a bit different, even older/newer same models.

Hope I’m on the right path and it helps others a bit to make a decision on adding a PID. If you have other issues, or see any with my operation, please don’t hesitate to ‘steer’ me right! I’m still new!

[OS OK]

Put your dial thermometer in a pot of boiling water and adjust it to read 212ºƒ...then you can trust it also.

If you put a garage on the hot plate and a BBQ thermometer (calibrated as above) in the top of the garage you can tell what temp. the moulds need to be...you can also pre-warm ingots on the top pf the garage also, then they will not have any moister in them when you drop them into the cast pot.

[Cast10]

Good advice! I’ll try that. I use a temp gun on the hot plate/mold and try and have it around 350-450. I like the ‘garage’. Thanks!

[OS OK]

When you re-stock the cast pot, you can set a 'filled mould' in the garage and go right back to casting 'keepers' when that pot is up to temp.
Do the same when you need to hit the head but I'm not advocating leaving the pot plugged in and leaving the shop more than a few minutes, like for a head call.

Never trust the 'plugged in' casting equipment without being 'eyes on' all the time.

PS...those temp guns are fickle...they read differently depending on the surface of what your reading. I think the 'darker color and more matt finish of the material tested' is closer to act temp. while a shiny surface is lower. Been a long time since I used one of them not sure I remember that correctly, in fact I gave mine to the guy who tinted my windows in the house...I stopped using it all together.

[Cast10]

OS OK. I’ve stayed on site when powered up.

So I did the water test.

Boiling - 212
PID 215.9 (+3.9)
Digital BBQ Thermometer 212
Tel Tru casting thermometer 210-212

Ice Water
PID 43.9 (+9.9)
BBQ Thermomter 34
Tel Tru - N/A as it starts at 200.

[oley55]

Initially, run auto tune as many times as it takes. If it keeps overshooting/undershooting, let things cool and run again. I ran it 3-4 times before I was satisfied.

There seems to be more folks brewing beer than casting boolits, so my PID operation searches generally produce more comments from the home brew folks. That said, the general consensus I have divined from these brewski folks are; drastic overshoots will be minimized if auto tune is activated when your pot is nearing your target temp and then let it do it's thing. Second, there is no reason or benefit for running auto tune multiple times. (hey it's just what I've read. No science or documentation so far.)

As I understand it, auto tune is for your initial PID setup. After that, the PID continues to learn and refine it's optimal settings. What I haven't found an answer to yet is, does running auto tune basically reset the baseline parameters and start new every time you run auto tune?

As recently as yesterday I added a second Auber PID to my project box so I can leave my primary lead pot PID dedicated to that and use the other for my other functions (PC oven, hot plate and salt bath annealing). Life would be easier if I built 2 more controllers, but one must choose where money is best spent. I think I have a better need for a second 4/20 pot so I don't have to empty when changing alloy.

[Cast10]

I do know when I ran autotune my P, I, and D parameters were changed each time. Thus the reason I stated earlier, record them.

[Cast10]

Re-tested and set PUF value/offset to 7.7. Boiled at 212. Will monitor next casting session.

This is necessary due to the thermocouple, not the PID.

[kbstenberg]

Off the wall.
Just today i ordered a second PID from Aubern the kit included the pid syl# 2352 / 40 amp ssr / K type probe / heat sink for 80$ shipped. Now i will have both pots controlled.

[popper]

does running auto tune basically reset the baseline parameters and start new every time you run auto tune?

Depends on the algorithm used (mfgr). It starts with a guess (mfgr value), adjusts parameters by looking back a period of time *minutes) and adjusts the 'guess'. It attempts to find the fastest temp rise without overshoot and smallest 'oscillation. I autotuned mine years ago, never done since. It has it's best 'guess' for a full pot. It only effects the startup heating and 'oscillations' (hot temp band). Set once and forget. I don't care how long it takes to melt, just want a controlled melted temp.
My advice. Melt your ingots in the pot, leave probe in the pot and let alloy get to room temp. Then auto tune once. these are made to use in liquids.