New To Me RCBS Pro Melt Temperature Is Off

[jonp]

Picked up a RCBS Pro Melt and a Lee Production pot at good prices. Both work fine but when I turned on the RCBS to 750 the temp on my thermometer went up to 700 then down to 650 and stayed there.

Any ideas?

[StuBach]

I use a PID with mine, crank to max volume and let the PID control the power flow to the unit. Never worried about the thermostat on the unit.

[dikman]

Those simple thermostats are notorious for being inaccurate. As StuBach said a PID is the only way to guarantee accuracy and consistency. If you've got a suitable thermometer to measure the lead temperature you could open it up and try adjusting the thermostat through trial an error - but it will be a long slow job.

[Mk42gunner]

I set the temp to where it worked with my alloy, then leave the dial alone. I may have used a thermometer, I don't remember.

I have had enough small switches fail in the closed position, I am not going to risk leaving a lead pot plugged in.

Robert

[beagle]

Set mine with a thermometer and let it alone. I tweak up and down on the flow as required.

Now, some of the pots and I don't recall which had a screw inside the shaft to the rheostadt that you could tweak up or down. Don't remember if the Pro-Melt is like that or not. Remove knob and see if the shaft is solid or hollow. If it's solid, no adjustment. If it's hollow, take a flashlight and look inside. If there's a screw, adjust it./beagle

I set the temp to where it worked with my alloy, then leave the dial alone. I may have used a thermometer, I don't remember.

I have had enough small switches fail in the closed position, I am not going to risk leaving a lead pot plugged in.

Robert

[kevin c]

So it seems like folks are saying that so long as the temp stays put at a particular setting, then just find the temp you want that works and leave the dial setting there. If the temp wanders, then you have a bigger issue.

Bypassing the temp control with a PID seems a good option, but will come at some cost (more if you buy, less if you DYI).

[fc60]

Greetings,

Fill the pot, turn it on and let it stabilize.

Loosen the set screw on the big dial and reset it to what your calibrated thermometer says.

The joy of buying used equipment...

Cheers,

Dave

[lesharris]

My Lyman pot had the hollow shaft and the adjusting screw.

[Mk42gunner]

So it seems like folks are saying that so long as the temp stays put at a particular setting, then just find the temp you want that works and leave the dial setting there. If the temp wanders, then you have a bigger issue.

Bypassing the temp control with a PID seems a good option, but will come at some cost (more if you buy, less if you DYI).

That's my take on it.

I wouldn't mind having a PID, but I don't think they are 100% necessary. Much like a thermometer, nice but not necessary.

Of course when PIDs became popular I was too broke for even the DIY option.

Robert

[kevin c]

My first pot was a Lee 4-20, which I understand has a rheostat temperature control. I found that I couldn't just leave the dial at a single setting; as the alloy level dropped the remaining alloy got hotter, so I had to tweak the dial periodically. I got a PID so I could just flip switches and not be hassled.

My ProMelt1 I think has a thermostatic control, but I got a second PID at a good price (I am NOT a DYI kind of guy for most things) so I use that, one controller for each (stacked pots, with the Lee feeding the ProMelt).

[Walks]

RCBS was kind enough to rebuild My Pro-Melt several years back. I guess I'm Lucky in that My 2 thermometers read within 10degrees of each other and the RCBS dial sets at what the thermometers say it should be.
I keep a dial thermometer probe in My pots at all time. Made a wire "rack" that keeps the probe 1/2" from the bottom of the pot liner.