PID Autotune - How important?

[Mike W1]

Received a pamphlet from Lyman and was looking at the Mag 25 instructions. First thing I noticed was that the Set Button and Digit Shift key are not used and are likely disabled. That would most likely eliminate the AT feature of the PID.

My units are used on several pieces of gear so I record the PID values and change to the gear being used at the time, but have noticed on the pots even a SV difference of maybe 50° doesn't seem to require that I autotune again.

Also noticed Lyman talks about a 10° swing which is higher than I've ever experienced with my PIDs.

Just something that came to mind reading those instructions. FWIW

[dikman]

Presumably trying to "dumb it down" for the average user and make sure they can't fiddle with settings? By giving a 10* swing it gives some leeway so people won't keep ringing them up complaining it's not "accurate"?

[georgerkahn]

I almost purchased a Mag25 until I read several comments re the PID on this site, in the unit itself. Perhaps getting hot from the pot, and both lack of close tolerance temperature maintenance and a predicted shorter life from the electronics being subject to this heat. From other folks on this site's recommendation, I instead bought a RCBS Pro Melt. Having this unit plugged into an outboard PID (bought from a vendor on this site) it amazes me with a modal six degree swing. (Obviously, when I add several ingots, temp drops -- I'm referring to normal bullet casting) If I had a Lyman, I'd probably turn its thermostat to maximum heat, drop my PID's outboard thermocouple into the pot, and use my outboard PID to regulate the temperature.

[10x]

Auto tune is not needed.
The original bimetal thermostat that comes with the older melting pots gave a range of alloy temperature and there was some "lag time" because of the position of the thermostat on the side of the pot.
A PID unit set to "on / off" mod (auto tune disabled) works much better than the old bimetallic thermostat. Using "auto tune" mod is fine tuning that isn't really needed or noticed.
I have used both auto tune and the "on / off" function and can't tell the difference.
The PID unit is more accurate because alloy temperature is measured from a thermocouple either in the alloy or attached to the wall of the lead pot

[HATCH]

Another thought is that Lyman may already of programmed the default settings to be compatible with their heating element.

[dannyd]

My Mag 25 works great