$25 PID controller for lube sizer

[bruce381]

I wanted to build a PID for my pot and thought I would try this first to learn how to do it.

Anyway I bought 1 of these PID and sensor:

http://www.ebay.com/itm/Microcompute...item540396bd52

And 1 of these:


http://www.ebay.com/itm/6mm-x-50mm-E...item35d232c160

Total shipped about $25 and once I figured out that the relay is only a off and on switch it works fine.

2 things I can point out the controller is in centigrade but is Ok
and the cartrige heater works too well.

The 200W heater get so hot so fast that when the controller turns if off it over shoots by 5 degrees or so.

I drilled a hole in the side of a 5/8x6x6 Al plate to mount my lube sizer on.

Kinda cool I did not like the shop light hanging on the sizer or the flate iron deal.

Any way try it out.

bruce

[bruce381]

Bye the way ebay has the controller and SSR and imersion sensor pakage deals for like $25 just wire and put in a mounting box for a Lead pot.

I will try this next, too bad the PID I bought for the lube sizer are not avalible in high temp for a pot.

[leftiye]

What did you use for a relay?

[bruce381]

its all inside just power to PID and sensor comes with it then just need a wire in a heater that's it relay takes up to 10A

[leftiye]

Thanks, Problem is I want one to control my melting/casting pot. Must work with 1000W and temps to 800 F. Good news is there is one on the suggestions part of the page you linked to. Your setup is cool as it has a cartridge heater included for the base plate.

[OuchHot!]

One of my PID is suspiciously similar to that one (except I paid more dang it) and the internal 10A relay has handled my Pro-melt and lee 4-20 without complaint for several years. ymmv

[leftiye]

Trick is to make sure to get a PID, and probe that will handle at least 400 degrees C (about 750*F) if you want to control a pot. I ordered a 25 amp separate relay with a heat sink just to be sure I had enough and not load it (before I read OuchHot's post), and a probe that will go to 1200*F. I'm revved up about this because my pot's temp control is older than the hills and shows wide variations (on the thermometer) as it cycles. I think this will put me very close to the "keep 'em all" situation.

I'm using a hot plate with an aluminum 1/2" plate on top to flatten out the hot plate's fluctuations. Heats up a mold right now too as the aluminum plate is a heat sink/reservoir. Also a 1/2 gal. can over the hotplate with a door in one side to conserve heat and make the heating more uniform.

As cheap as this was, I might put a PID on the hot plate too.

[6bg6ga]

I hate to throw cold water on the size of those internal relays but.... those contacts are extremely small. I have several of them sitting on my bench right now and they don't seem to hold up well. If you experience trouble a simple cure would be to use the internal relay to run an external relay of a larger size. The internal relay would simply turn on/off the control voltage to the external relay. The external relay would take the heating load. Sorry, but years of electronics has taught me to be on the cautious side when using those Korean and Chineese relays.

[bruce381]

Yeah I took tjhis one apart tying to see if there was a switch to change from C to F ( no switch dang) anyway the relays are small like that is in a modern car relay box for flashers etc.

But for a 100W heater in my lube sizer works fine.

Ebay does have high temp "real" PID controller Kits with PID, SSR 25A and sensor all shipped for about $25 so my next project will be a controller for my pot.

[OuchHot!]

hmmm! I may have a pitted relay in my future...thanks for the heads up.

[6bg6ga]

hmmm! I may have a pitted relay in my future...thanks for the heads up.

I'm not going to say it can't or won't happen with a maximum load. The contacts are very small to be capable of 10A of current.

[Bored1]

Nice idea there! May be ordering one in a few weeks to try out myself.

[OuchHot!]

I've got two of these PID cheapies in a box, one for the hotplate and one for the pot. The hotplate draws far less than the pro-melt so I think that I have room for a (bigger) relay left in the box to drive the pot. I cannot say for sure, but I know that I have 100hrs on the system but that isn't so much in the scheme of 4-5hr casting sessions.