Pid

[MR CHEN]

I have one of HATCH'S PID"S and have some questions...
I know that I can go to the "source," but I'm going to ask here first.

I understood that once the pot was turned on, the "auto tune" would start, run it's cycle and hold the set temp, witch it does well. With my pot the Lee 4-20 this takes about 45 minutes.
The online info said you only have to do this once.

So my questions are:
Is it normal for the PID to auto tune each time the pot is turned on? Which it does.

And should the PID go into auto tune each time material is add back into the pot during a casting session? Witch it does.

[Mike W1]

In short, NO. AT is something you turn on, not something that happens automatically. It should turn off automatically when it has completed ATing. My recollection of the unit I think he uses is a Mypin and when I had mine I "thought" I was running AT but really wasn't as I was looking at the wrong indicator! Something lined up oddly as I recall.

[Minerat]

I just went thru the same thing. I AT'ed it twice before I realized that the blinking red light when going thru the AT process is faster then the cycle the PID goes thru to keep the pot at the set temp. I find on mine that the temp will vary from +-1 degree once it reaches the set temp and the red light goes on and off in an irregular pattern unlike when Auto tuning, that has a steady cadence.

[Mike W1]

Couldn't find a better picture but I think what I was doing wrong first was pressing the button below the AT symbol (the one clear right in the picture) instead of the actual button which is 2nd from left. That flashing red light on the left side indicates when power is actually being sent to the pot. Can't tell from the picture (or my memory) what color AT shows as but it would be a steady light when engaged and would be clear to the right. When it's done ATing it would be extinguished.

[MR CHEN]

The one I have is a GOLANDER.
The red light indicator on the far left does blink fast while auto tuning then blinks slower when cycling on and off to maintain pot tempt.


Why would it go into auto tune when the sprue and rejects go back in the pot? The tempt does not go to the set point and then maintain. It over shoots a lot like when in "auto tune."

And like I said earlier, turn the pot on and it's 45 min of "auto tune" each time.

[Mike W1]

http://castboolits.gunloads.com/show...ntroller-(PID)
Check thread above! I gave up trying to figure that brand out. Or better yet let Hatch clear it up for you.

[HATCH]

its much much faster and easier if you would of just sent me a PM.

First - it does NOT do autotune every time you turn it on. Initially the PID should blink a few times then go SOLID until it gets closer to temp. Then it blinks to maintain.
Second - If you read my FAQ you would of send this "To activate the auto tune function, press and hold the > key until the “AT” indicator starts to blink. When auto tune process finished, the “AT” indicator will stop blinking."

You must run the autotune initially. It will reprogram the settings to match your pot.
Once finished the PID is tuned to your pot and will operate MUCH better.

The PID has a generic heating curve in it from the factory. It may work great for your setup or it may not.
Generally speaking without running autotune you will get overshots.
So lets say your set point is 750, you could see temps go above 800 using the default heating settings.
It would take a while to get the temp to be stable.
So run the autotune -> To activate the auto tune function, press and hold the > key until the “AT” indicator starts to blink. When auto tune process finished, the “AT” indicator will stop blinking.

CHARLES

[HATCH]

Let me clarify something so you understand.

The AT light is also the output light for the SSR
When you add lead to your pot, it will blink or go solid depending on the temp drop of the lead in the pot.
On initial start up it will blink several times then it will go solid until close to set point.
Then it will blink around set point to maintain the temp.
So it is not UNUSUAL for it to blink.

Imagine you have a rocket and your throttle is either OFF or WIDE OPEN.
So your trying to go 750 mph. So initially you give it wide open throttle so get it up to speed.
Well you have to guess how fast the rocket will slow down when you let off the throttle as you don't want to go much faster then 750.
So the first time you guess wrong on go 775.
So you let off and when it gets to 725 you give it more throttle.
But this time you learned that if you let off the gas at 740 that it will stop accelerating around 760.
After a little while you learn that if you just pulse the throttle on for 1/2 a second then off for 1/2 a second that you can maintain 749-750.
That is after you got up to that speed.

Hope that helps you understand what is happening
CHARLES

[MR CHEN]

http://castboolits.gunloads.com/show...ntroller-(PID)
Check thread above! I gave up trying to figure that brand out. Or better yet let Hatch clear it up for you.

Thanks for that link, very educational.

[MR CHEN]

Let me clarify something so you understand.

The AT light is also the output light for the SSR
When you add lead to your pot, it will blink or go solid depending on the temp drop of the lead in the pot.
On initial start up it will blink several times then it will go solid until close to set point.
Then it will blink around set point to maintain the temp.
So it is not UNUSUAL for it to blink.

Imagine you have a rocket and your throttle is either OFF or WIDE OPEN.
So your trying to go 750 mph. So initially you give it wide open throttle so get it up to speed.
Well you have to guess how fast the rocket will slow down when you let off the throttle as you don't want to go much faster then 750.
So the first time you guess wrong on go 775.
So you let off and when it gets to 725 you give it more throttle.
But this time you learned that if you let off the gas at 740 that it will stop accelerating around 760.
After a little while you learn that if you just pulse the throttle on for 1/2 a second then off for 1/2 a second that you can maintain 749-750.
That is after you got up to that speed.

Hope that helps you understand what is happening
CHARLES

First let me say that I did read your FAQ, and performed the auto tune with no problems. It's was what that was happening after , that confused me.

Yesterday afternoon I fired up the pot and watched the entire heating prosses, it unfolded just like what was described.
I now understand what is happening..... But you have to admit, it looks a lot like auto tune.

Thank you Minerat, Mike W1, and HATCH.