Electronic temp control

[Lee W]

The RCBS pro pot does use a themostat. Not that I have taken one apart, I know where they get them from.
Look here for a little more info.

http://castboolits.gunloads.com/show...37&postcount=8

[jsizemore]

The RCBS pro pot does use a themostat. Not that I have taken one apart, I know where they get them from.

Well. What's the model # and where do you get it. Come on, share.

[Lee W]

Unfortunately you can get replacements only from RCBS. It's a contract thing.

[thebigmac]

YOU OLD GUYS WITH YOUR ANCIENT SAECO AND LYMAN LEAD POTS NEED TO DO WHAT I DID.
(Plastic Process Equipt. Inc--8303 Corporate Park Dr.---Macedonia, Oh. 44056). IS THE PLACE TO CONTACT FOR A REPLACEMENT THERMOSTAT. I JUST COMPLETED REPLACEING MINE, AND WITH A LITTLE MINOR ENGINEERING(?) MADE IT FIT. WORKS GREAT, JUST LIKE HAVING MY OLD POT BACK. YOU WANT MODEL B-200. SORRY, DON'T HAVE ADDRESS OR WEB, BUT GOOGLE IT.. WORTH A TRY. $23.00 PLUS UPS/// Mac

THAT WEB SITE IS; WWW.PPE.COM AND YOU WANT PAGE 702.. Mac

[TAWILDCATT]

I just repaired my old Saeco.$15 at harbor freight. its called a router speed control.I jumped the old control and pluged into the speed control,works great.
its actuall a voltage regulator and is rated 115 vts at 15 amps.which comes to 1700 wts.

[lurch]

Just about any of the K thermocouples will work. They are all high temperature insulation good for at least 900 deg. The outer sheath is typically stainless steel which is good to a higher temperature than the carbon steel of the Lee pot. I welded a 1/4 20 nut to the bottom of the pot & screwed the Model: TC-K6 thermocouple in it. You can see the lead in the picture.



If you don't want to weld then just get one of the probe type TCs like Model: WRNK-171S & put it in the lead from the top of the pot. You will need to make a bracket out of wire or the like to keep it submerged in the lead.

The Aubner web site has the manuals for the controllers on line. Download one & they show sample wiring diagrams on pg 12. They show all the extra features it can do like actuate alarms but the only connections needed are power to the PID controller, the 2 wire connection for the TC(make sure you get the polarity right) and wire the PID internal relay in place of the thermostat in the pot. The terminals on the PID are all marked as to their function. Here is a wiring diagram for the numbered terminals on the back of the PID. The fuses are optional, I didn't use any.



The PID is set up with default parameters for K type TCs & an avg control. It worked great for me with the factory settings. If you want to get fancy, the instructions show you how to turn the learn mode feature on so that the PID will cycle on & off about 3 times while it watches the temperature response of the pot. It will set the parameters for the best operation based on that. It is very simple.

BTW, Here is the original thermostat for the Lee Production Pot. As you can see it is not really a true thermostat, it does not read the temp of the lead. It is a timer, it cycles on & off with the heating of a bimetalic strip. This is the part I took out & replaced with the PID.

I too found the temperature control on the Lee pot somewhat lacking and added a PID control to it in a very similar fashion to this. I found it to make a world of difference.

Some suggestions if anyone decides to go this route:

1. I would be a little afraid of mounting the housing for the controller directly to the column on the back of the pot. The column gets plenty warm in normal operation and will transfer that heat to the controller housing. Electronics in general don't much care for heat unless they are designed to take it, and even then, elevated temperatures will shorten their life. If you want to mount the controller housing to the pot I would at a minimum uses some standoffs so the controller housing is at least a half inch away from the pot column. An even better solution would be to mount a heat shield (simple piece of aluminum or other metal) between the column and the controller housing to keep radiant heat from affecting the controller housing temperature too much. You need an air gap between the column and the heat shield, and an air gap between the shield and the controller housing. No need to get crazy with the gaps, 1/4 inch so on each would be fine.

2. If you use a controller with a direct relay output, set the cycle time to a larger value. This will reduce wear & tear on the controller output relay contacts, extending their lifetime, without causing any detrimental effects on the ability to control the lead temperature accurately.

3. Some controllers have an output that is intended to drive a solid state relay. If using the solid state relay, the relay will need to be mounted on some form of heat sink. If the add on housing is large enough, simply mounting the relay to the housing will suffice. The relay does get a little warm when starting up a cold pot as it stays on continuously for the first few minutes. Once things are up to temperature and the relay starts cycling, the amount of heat generated by the solid state innards of the relay generate significantly less heat.

4. I mounted the thermocouple to the bottom of the pot using a welded on 1/4-20 nut as well. I found that to get a good bite in the threads, I needed to use a spacer to set the nut off the pot by about 1/8 inch or so. The reason is the thermocouple has a "button" on the end that wouldn't let more than a thread or two engage the nut before the button bottomed on the pot. A taller nut would work as well in place of the spacer.

5. No. 4 generated an issue with the nut bearing on the bottom cover of the pot and the bottom of the pot started acting as a heat sink, dropping the temperature that the thermocouple saw. This caused an offset (OK - not a true offset, but in the casting temperature range, it looks like a fairly constant offset) from what a traditional immersion thermometer was reading. You can either ignore this and simply set the desired control temperature higher on the controller or you can insulate the nut from the bottom cover of the pot and any ambient airflow. Be sure and use something that can take the heat like some Nomex (look up Aramid strips at McMaster-Carr) or mineral wool.

Kurt

[Norseman]

I finally found a suitable box in the dumpster at work today. The entire evening have been used to fit the wiring inside.

So now, I have a box with a socket that I can plug my 4-20 or my Production pot into it and use the same thermocoupler on both.

I have the thermocoupler floating ontop of the melt, but I don't think there's much variance of the temperature in the melt.

[angus6]

Think I'll order an extra and add to my lee pot as I need to pick up a new one for the Bullet Master
Thanks for the link , great price

[TAWILDCATT]

I did it the cheap and easy way.HARBOR FREIGHT HAS A ROUTER SPEED CONTROL.
IT IS A VOLTAGE CONTROL plug it into power and plug the pot into the control box.
$15 to $19.depends on sale.works on my Lee and Saeco.

[RoyRogers]

I did it the cheap and easy way.HARBOR FREIGHT HAS A ROUTER SPEED CONTROL.
IT IS A VOLTAGE CONTROL plug it into power and plug the pot into the control box.
$15 to $19.depends on sale.works on my Lee and Saeco.

How constant does the speed controller keep the temp? Did you bypass the factory control?

[evan price]

A PID controller is the simplest thing in the world to use.

I used to build steam-heated autoclaves and I used either proportional control with a pneumatic transducer to activate the steam valve with a diaphraghm, or a direct-acting pneumatic solenoid activated valve for on/off control. Proportional control is really cool- you can teach the controller the thermal characteristics of the device and it will hold your setpoint temp at the level of accuracy of the PID controller- we were holding +/- 0.5 degree F at 300 degrees F.

I added a PID to several pieces of my equipment such as the label marking machine and the Lee pot; the only thing I would advise is to go ahead and add a cheap "ice cube" relay to drive the heater instead of direct wiring- a $5 relay is a cheap replacement in case of failure VS a new PID controller.

Oh yeah, and with the "J"-type thermocouples, there are two wires, one red, one white- and the red is NOT positive, the white is.

[sciguy]

A PID controller is the simplest thing in the world to use.
I added a PID to several pieces of my equipment such as the label marking machine and the Lee pot; the only thing I would advise is to go ahead and add a cheap "ice cube" relay to drive the heater instead of direct wiring- a $5 relay is a cheap replacement in case of failure VS a new PID controller.

Oh yeah, and with the "J"-type thermocouples, there are two wires, one red, one white- and the red is NOT positive, the white is.

Evan,

Which specific PID would you recommend for this conversion? Link appreciated
I agree that the relay takes pretty much all of the wear and tear and is cheap to replace.

Best Regards,

Hugh

[RoyRogers]

A PID controller is the simplest thing in the world to use.

I used to build steam-heated autoclaves and I used either proportional control with a pneumatic transducer to activate the steam valve with a diaphraghm, or a direct-acting pneumatic solenoid activated valve for on/off control. Proportional control is really cool- you can teach the controller the thermal characteristics of the device and it will hold your setpoint temp at the level of accuracy of the PID controller- we were holding +/- 0.5 degree F at 300 degrees F.

I added a PID to several pieces of my equipment such as the label marking machine and the Lee pot; the only thing I would advise is to go ahead and add a cheap "ice cube" relay to drive the heater instead of direct wiring- a $5 relay is a cheap replacement in case of failure VS a new PID controller.

Oh yeah, and with the "J"-type thermocouples, there are two wires, one red, one white- and the red is NOT positive, the white is.

I thought an icemaker used a timer that controlled a solenoid valve? You talking about modifying a solenoid valve to close a set of contacts?

The PID referenced here has a built in relay. Any problems using the built in relay?

[TAWILDCATT]

I dont know how constand as I would guess it might change as the pot got empted.I will find out today if I feel up to casting and the rain does not come.It is a constend on.not a make and break. and yes I jumped the thermostat as it was bad.there is an on off and constant switch.and the Price is between $15 and $19

[lurch]

The PID referenced here has a built in relay. Any problems using the built in relay?

The problem using the internal relay is that it will wear out eventually - contacts usually give up and once the internal relay is gone, get a new controller. This may or may not be a concern depending on how you look at it.

The Lee element is around 700W resistive. I would want a relay rated 10A, 120V resistive as a minimum for any life expectancy at all - preferably substantially more rating. If you can get that, set the cycle time on the PID control for at least 10 to 15 seconds. This will reduce the number of times the relay contacts have to actuate and prolong their life. I'm guessing that the cycle time could even be set longer without introducing significant ripple in the temperature of the melt - just have to try and see.

The advantages to the solid state relay are that the external relay is:

1. Cheap (relatively) compared to a whole controller if it does fail.
2. Easily replaced
3. Not generally prone to wear out (though you may very rarely get one that fails rather soon due to infant mortality. If it lasts a while, it's probably going to last a very long while as long as you keep it from getting too hot)
4. Not bothered by a short cycle time wearing out the contacts - none to wear out.
5. The cycle time set at two seconds becomes a nice timer for keeping you casting cadence constant.

I'd get one rated 25A or better and use that if it were me - and it was a while back. No problems so far - thousands of boolits later...

[sciguy]

The advantages to the solid state relay are that the external relay is:

1. Cheap (relatively) compared to a whole controller if it does fail.
2. Easily replaced
3. Not generally prone to wear out (though you may very rarely get one that fails rather soon due to infant mortality. If it lasts a while, it's probably going to last a very long while as long as you keep it from getting too hot)
4. Not bothered by a short cycle time wearing out the contacts - none to wear out.
5. The cycle time set at two seconds becomes a nice timer for keeping you casting cadence constant.

I'd get one rated 25A or better and use that if it were me - and it was a while back. No problems so far - thousands of boolits later...

Lurch,

Could you do us a huge favor and throw up a link to a specific relay that looks pretty ideal. I would also love one to specific PID contoller as well.

Thanks a ton for great information,

Hugh

[lurch]

Links:

Here are a couple of suitable controllers, slightly different different but capable:

http://www.auberins.com/index.php?ma...products_id=14

http://www.auberins.com/index.php?ma...&products_id=3

The relay I'd use is this one:

http://www.auberins.com/index.php?ma...&products_id=9

This is just the stuff from Auber. There are lots of similar on evil bay from other sources. It all comes from China and I'd almost bet from the same shop with a different sticker on the front.

Depending on how you physically set the thing up, you may or may not need a separate heatsink for the relay. In my setup, the relay and controller are in a steel box that used to house a cheap venturi vacuum pump from Horror Freight. Mounting the relay to the inside of the box with a little heatsink compound transforms the box into the heatsink as well as mechanical enclosure. DO NOT mount the controller or relay to the back of the pot - it gets way to hot there for long life of electronics. If you go plastic or wood for the box, you need a heatsink.

[sciguy]

Lurch,

Just the information I was lookig for. Thanks so much!!!!!

Hugh

[RoyRogers]

Rough math is $80 for all the parts listed above - including a $20 high temp thermocouple. Add that to a $70 Lee pot comes to $150. Better overall value than ~ $300 for an RCBS pot?

[Ugluk]

I got me a PID from Auber Instruments for my home made bottom pour, and I LOVE IT!
Now I'm gonna get me an external relay so I can keep loving it for years to come.. Thanks for the heads up in burning the PID out.