JLD612PID/Lee 4-20

[Jeffjmr]

Having a significant overshoot problem with my PID setup. 650 set goes to almost 750 every time, but then eventually settles to 650 and does a reasonable job of maintaining it there.

Autolearn only goes through one cycle. I have tried manual settings, with same result. Is overshoot just something I'll have to accept with this setup or are there settings that will eliminate this? I have already tried setting SouF to max with no improvement.

K type Tc half inch tall in bottom center of pot.

Anyone else with this setup with better results?

Thanks,
jeff

[Jeffjmr]

Am I the only one using the JLD612?

[Mike W1]

Am I the only one using the JLD612?

Not a unit I'd seen mentioned before. Gonna download a manual for it and take a peek tomorrow about it but it seems strange it could autotune with only one cycle below and above set value. Thought they had to do 3 cycles to "learn".

[Jeffjmr]

Not a unit I'd seen mentioned before. Gonna download a manual for it and take a peek tomorrow about it but it seems strange it could autotune with only one cycle below and above set value. Thought they had to do 3 cycles to "learn".

Exactly. It goes full power, turns off at the set (650) coasts up to about 730 then slowly drifts down to 650 at which point the AT light goes out and it holds 650 +/-. Have done it about 10 times. Same result each time. The if I start again cold, it does start to pulse the power as it approaches 650 but overshoots anyway just not quite so badly as when in auto tune.

i have since experimented with manual settings and am getting the overshoot down to about 25 degrees which is much better. When I finally get it right I'll post the results. I know others are using the JLD612 as there is a sticky here where it is used. But the parameters are not mentioned.

thanks, Mike.

[Mike W1]

Well I guess then it's working with 1 cycle. Looked around for a manual and downloaded several which all turned out to be the same one with a different file name. Didn't learn much actually though. Never had to do any tweaking on my units that affected performance so haven't a clue towards being any help. AT does the PID values quite nicely on mine. It did look like your unit is pretty resatile. AC or DC inputs on some, SSR or relay. Even looked at some discussions on the web and still drew a blank. They were talking WAY over my head.

[JonB_in_Glencoe]

I use the JLD612
The first time I tried it out and did the autotune from cold.
I got similar results as the OP.

The second time, I brought the alloy up to temp, then added another ingot to drop the temp about 50 degrees and then pressed autotune. I got much better results. Ever since then, when I plug it in and pot is cold, I get a 10º overshoot, as the temp comes down (takes about a minute or two) to the set temp, it holds that nicely.

[Jeffjmr]

I use the JLD612
The first time I tried it out and did the autotune from cold.
I got similar results as the OP.

The second time, I brought the alloy up to temp, then added another ingot to drop the temp about 50 degrees and then pressed autotune. I got much better results. Ever since then, when I plug it in and pot is cold, I get a 10º overshoot, as the temp comes down (takes about a minute or two) to the set temp, it holds that nicely.

Now that is something I haven't tried. Figured cold start would give best results. Thanks JonB.

In the meantime, next time you get the chance could you make a note of all your parameters in case my hot start AT doesn't work?

thanks again,
Jeff

[JonB_in_Glencoe]

Now that is something I haven't tried. Figured cold start would give best results. Thanks JonB.

In the meantime, next time you get the chance could you make a note of all your parameters in case my hot start AT doesn't work?

thanks again,
Jeff
I finally got around to casting some boolits today, and took down my parameters.
P=1.0
I=111
d=27
Souf=0.2
ot=2
FiLt=0

Did you have any luck with the HOT start ?

[Jeffjmr]

A belated thanks for the parameters. Work had precluded any casting for a while. I took the shotgun approach, simply experimented with wildly different parameters until I zeroed in on a workable set. I'm going to try yours next time though and see if it improves.

Thanks again.

Jeff