Using a Master Pot PID to control my lube heater

[Pardini]

I have a Master Pot with a TOHO TTM-J4 PID. It has output 1 and output 2 on the display. I thought I could probably use output 2 to control the lube heater. After finding the diagram online that doesn't appear to be possible.

Will it work, If I get a second thermocouple and mount it on my sizer and unplug the one on the pot, then connect the sizer to the PID? I wonder if the temp is going to greatly overshoot on the sizer after having been connected to the pot.

[Mike W1]

I'm sure it COULD be done but seems like a pain in the rump to me. Never having even laid eyes on a Master Pot I have no idea what you're looking at space wise to add a plug in panel type thing for the TC's. Most likely enough for that and then I'd add a SPDT switch and outlet to plug the lube heater into. If it were me I'd just build another unit with a Rex that has SSR output. You're only gonna set it infrequently anyhow, if ever, and Celsius isn't that hard to live with.

If you go the route you're talking I'd think you'd be better off recording the settings for each unit and changing them. Or hopefully that PID has an Autotune feature. Definitely check that part out first.

[bangerjim]

It may have O1 and O2 on the display.....BUT......does it have separate INPUT 1 and INPUT 2 on the back??????? That is the key info. It would be odd they would go to the high expense of a dual channel controller for a lead pot.

Just buy another cheeeeeeep controller+ t/c for your greaser.

banger

[Pardini]

Only one TC input, but it does have a QD on the TC lead and also on L1, N and G going to the pot heater, so swapping from the pot to the sizer would be easy enough. PID has a self tune feature, but unsure how to activate it, may not be enabled from Magma? I don't have in depth knowledge of PID's. If I stick a TC on the sizer and plug it in to the PID and set the temp to 100*F what will I get? Liquid lube? Is the temp going to over shoot by 10, 20, 60 degrees the first few cycles then stablize at 100?

[bangerjim]

Controllers are designed and made to be connected to ONLY ONE loop....not swapped back and forth. The auto tune will work very well after some time up and running. Every time you swap the controller to another set-up, it has to go thru all that "learning" again. Not worth it. By the time it learns what the temp profile is, you are probably done.

Buy another controller for your heater if you think you absolutely need it. These little cheapo controllers everywhere on the net are perfect for a simple control like that.

As far as over/under shoot.....it depends where you have the proportional/integral/derivative parameters set......or if the auto tune has been running long enough to learn the dynamics of the loop. There are many factors that come into play, such as the size of the device you are heating, the wattage concentration of the heater, the heat transfer rate, the heat loss over time.

PID controllers are a nice thing, just not a cure-all for everything you use that gets hot!

I have been designing PID-based industrial control systems for over 35 years that control pressure, temperature, flow, speed, level, etc.

Good luck on whatever you plan on.

bangerjim

[edctexas]

You can swap PIDs between controlled items. When I am happy with the control, I copy down the control parameters. There may be more than PID on digital controls. You can swap to the new device and auto tune on it. When you are happy, copy down the parameters. When you change back, just change to your noted set of parameters. It may be easier than that! You could be lucky, My control for the PC oven has very similar parameters as the one used on the hot plate. But you units could be different. It is a lot of fooling around to save the 35-50 bucks for a separate PID.

Ed C

[tja6435]

A cheap way to make a lube heater is a 1/2" thick aluminum plate ($15)with a 3/8" hole drilled through it and a 100w element heater ($9) with a 600w dimmer switch ($7)wired inline on a cheap extension cord ($2). Just set the dimmer to the heat needed and click it on/off.

[bangerjim]

A cheap way to make a lube heater is a 1/2" thick aluminum plate ($15)with a 3/8" hole drilled through it and a 100w element heater ($9) with a 600w dimmer switch ($7)wired inline on a cheap extension cord ($2). Just set the dimmer to the heat needed and click it on/off.

This actually works very well. I have built a number of control boxes like that for soldering irons and pyrography tools. There is no feedback, but the steady-state heat control works well, once you know where to set the dial.

[fecmech]

An aluminum plate with a clothes iron on it gives very uniform controllable heat for a lubrisizer. I use it on both of my Stars.