Help me with my PID please

[chrisx1]

Hey guys,

I need some help as I build this PID Controller for my Lee pot.

Here's what I've got so far:

Components:

http://i264.photobucket.com/albums/ii174/chrisx1/IMG_1169.jpg

Pid from Lee's benefit sale, switch, temp probe, solid state relay, old bluetooth headset charger for DC power supply, terminal strip and fuse holder.

I bought a project box from Radio Shack, but it's going back. For one its too small - I don't think I could fit everything in without a lot of effort, and maybe not at all. So I started looking around the reloading room for a box big enough and I found this:

http://i264.photobucket.com/albums/ii174/chrisx1/IMG_1173.jpg

I bought a new Glock a while back, and didn't like it - when I sold it, I forgot to give the guy the box. Anyway, I shouldn't have any problem getting all the stuff in this box.

http://i264.photobucket.com/albums/ii174/chrisx1/IMG_1171.jpg

I've got the holes cut for the PID, the switch, and the plug for the probe.

http://i264.photobucket.com/albums/ii174/chrisx1/IMG_1172.jpg

I think it will turn out o.k.


I have a question: What type of glue/adhesive should I use to hold all these components in place? I don't want all this stuff to just be rattling around in the box do I?

.

[Artful]

I don't have a glock box but on some projects I have used the hot glue gun to tack 'em down.

[frankenfab]

Ha! Incognito PID disguised as handgun case! Better watch out who you show that one to. They might think it's a B-word.:grin:

I would try to get terminal strip in particular as well secured as possible. If the plastic's thick enough, you cou use small countersunk screws (without countersinking the plastic) through the bottom and nuts and washers on top.

The hot glue suggested is not a bad idea. I also thought of two-sided tape or industrial strength velcro.

The SSR may get warm, so if you could mount it with 2 runners underneath to create an airspace, that would be good.

Don't ask me how to wire it, though. I have no clue! But I think I could eventually 'gitter done.

[bohica2xo]

That SSR might not live very long in a closed up plastic box with no heatsink.

B.

[Casting Timmy]

You can also drill through and use a bolt and nut to hold them in place. I like your idea of using a gun box to house everything. I used a plastic box....used zip ties on both sides of my power wires to keep the wires from sliding in and out of the box.

I used to do remote control cars and they had some really good double sided foam tape. Or certain hobby stores have sticky dots that can secure it in place without using heat.

No saying hot glue is bad, just trying to give a few different choices.

[chrisx1]

I have some 3M auto body tape - the kind you stick mouldings on your car with - I think I'll try that. We are going to have to do something about the heat from the SSR....didn't really want a fan, but looking like we may need one.

O.K. - next question: My temp probe has a blue wire and a red wire - does it matter which one goes to the + or - ?? The little plug setup that I bought is also coded for + and - so I'm guessing that there is a right way and a wrong way to wire it?
Also - can I use copper wire from the PID to the plug, or do I need to use thermocouple wire?

Thanks for the help and comments,

Chris

.

[Lee W]

Chris,
Only use thermocouple wire to extend it. You could cut off a small section and run it to the controller. You seem the have the correct plug.

Thermocouples are polar, connect to backwards, the temp will go down when heated.

http://www.omega.com/techref/thermcolorcodes.html

[lurch]

That SSR might not live very long in a closed up plastic box with no heatsink.

B.

Bingo...asking for trouble on that point. That thing needs a heatsink with the fins exposed to the outside - all the way outside.

[lurch]

Also, the fins need to be oriented so that they are vertical and have unobstructed airflow from bottom to top. i.e. the open ends need to be the top and bottom and the bottom should not sit directly on any surface that blocks them. Leave at least as much room from the bottom to the bench/table as the fins are deep.

[RaymondMillbrae]

Gun case?

Cool idea. I love it. :)

As for what to use to fasten down the parts:

For the barrier strip and SSR, just drill a few hole in the plastic case and screw them down. (Make sure the nuts are on the inside).

As for your AC to DC adaptor, you can use any 2-part epoxy, or Acraglas gel. (If you happen to have some laying around from an old rifle bedding job). Just make sure to scuff-up the two parts before adding the epoxy to it. This will ensure the epoxy has a good hold on both surfaces.

Oh yea...take everyones advice...add a heat sink to your project.

In Christ: Raymond

PS: The gun case is a great idea. If you can figure out a way to "compartmentalize" an area within the case, it would be awesome to be able to store the thermocouple and cords inside. (Food for thought). ;)

http://xb9.xanga.com/8c0f506459531265602146/o211816004.jpg

[chrisx1]

O.K. - I get the point.....I need a heat sink.

How about this one? I found it in an old computer I had sitting around.

http://i264.photobucket.com/albums/ii174/chrisx1/th_IMG_1208.jpg (http://s264.photobucket.com/albums/ii174/chrisx1/?action=view&current=IMG_1208.jpg)

Is it big enough?

I can configure as described by Lurch above - use thermal epoxy to attach it to the SSR, and get the fins thru the box.

I'll wait to hear some opinions before I cut any holes in the box.

Thanks again for all the help.

Chris

[RaymondMillbrae]

Get something larger.

Here are a few pictures of the ones I have installed.

In Christ: Raymond

PS: These were cannibalized from older computer mother boards.

http://xcb.xanga.com/b2af66ea77632266099278/b212231053.jpg

http://x96.xanga.com/1dbf70f633433266099434/b212231183.jpg

http://x8c.xanga.com/1e0f406420430265601871/o211815750.jpg

[Frozone]

How about this one? I found it in an old computer I had sitting around

If you happen to have an old PC around, the stock sink from the Pentium or Athalon CPU should be enough for a LEE 20# ( or under 7A )

While they seem to be getting rarer, If you have a "used computer" store in your area they will have old CPU sinks and should part with one cheap.
Or keep your eyes open as you drive, many people put their 5+ year old boxes out on the curb as junk. They will have likely a useful sink in them.

[chrisx1]

Yeah, there is a bigger one in that computer I have ... I'm just not sure how it's all going to fit in the box yet.

[lurch]

Another thought...

Do you have or can you get a piece of 1/8" or there about aluminum (or steel...but aluminum preferred) sheet? A piece with a big enough surface area (maybe 6"x 6" as a guess) could be mounted to the box you have with some bolts and some washers stacked to space it off the box some - may 1/4" to 3/8". Cut a hole in the box that the relay will slip through and then bolt the relay to the aluminum plate heatsink you just made. The terminals of the relay should still be inside the box and away from fumble fingers when in operation. For safety sake, attach a ground wire to the aluminum plate as well.

Not sure how you were envisioning putting your bigger heatsink "in the box", but putting the heatsink inside the box and closing the box defeats the whole purpose. There will be no air circulation to let the heatsink work. OK - the will be some, what little is in the box, but it will just heat up and kill most all of the benefit that the heatsink could provide. There is no real way to get the heat out of the box like that, unless you cut some fairly substantial vent holes in it. Plastic is generally a poor heat transfer medium.

[lurch]

Oh...for this to work your box would have to sit on its hinges during operation. Air circulation again... Might not be too practical after all...but a thought.

[Frozone]

Using the layout I see in your first post (in pix 3).

Turn the SSR upside down and mount it to the 'lid'. That way you'll run the sink on the top of the box. It'll be a little exposed but it'll get enough air flow that way too.
Since you have a 12V supply you can use the fan on the CPU heat sink, if it has one. You'll get more than enough cooling that way.
If you also use Lurch's suggestion and use a 6"x 6" piece of AL plate, you can add more than one CPU sink the top of the plate (SSR is on the bottom) and get all the cooling you can stand.
Be sure to use heatsink grease on Both sides of the plate.

[chrisx1]

I mis-spoke (sound like a politician) about the heat sink Lurch - should have said "through the box"

I understand the concept around the heat sink - I just didn't realize at first that the SSR would generate that much heat.

Chris

[Frozone]

I just didn't realize at first that the SSR would generate that much heat.

Chris

Most of the time it won't. But on a hot day, and as the pot heats up it'll be as warm as it'll get. You could use the smaller sink you showed much of the time. It's that 10% close to max that'll get you. It pays to keep the SSR under 120*.

[RaymondMillbrae]

Here is something else you can do to keep the heat down:

1) Plug the pot directly to the household 110v outlet, and melt the lead.
2) Once the lead has been melted...THEN plug the pot into your PID temperature controller.

Since the lead will already be melted, the draw for power will be much less. The SSR will now stay cooler, as it will be "cycling" ON and OFF instead of staying ON continually to initially melt the lead.

Did that make sense?

I'd be interested to see your finished product.

I am pretty much done with my tutorial, but I am waiting on a clear day (no chance of rain) to smelt some lead and show the PID temperature controllers in "action".

Best wishes, and shoot with a purpose.

In Christ: Raymond

[jimmeyjack]

Hurry up Raymond its gonna rain sunday!
I can't wait to see yours so I can put mine together[smilie=1:

[RaymondMillbrae]

Drats!!

It's Friday, and I just got back home from a crazy work day in Campbell.

I have a mandatory meeting Saturday morning at 0800 hours, and then I'm gonna try to shoot over to Richmond for a few hours of practice.

If all goes well, I will finish everything off after that.

Oooooor if the meeting lasts too long, I will scratch the Saturday Richmond practice, and just dedicate the rest of the day to this PID project.

Boy...44-years old...still running around like a mad-man on crunch time. Where do the hours in a day fly to?!

In Christ: Raymond

[Rock]

The K type probe that I acquired is longer than needed (the probe and the wires).

Is it possible to cut the probe and wires to a shorter length?

If the probe cannot be cut, can it be bent?

Thanks all

[lurch]

My *guess* is that the probe could be bent as long a it's not bent too near either end and the the bend is done with a nice radius so as to not crush the wire inside it. I would definitely not try cutting it. As far as I know, the probe is just a metal sheath around the thermocouple wire. There may be some sort of different insulation material inside the probe as well (again, a guess as I have not pulled one apart). If that insulation is amenable to bending then it should be OK. If not, then...oops... I suggest contacting your vendor and asking to be on the safe side.

As for the wires, there should be no issue at all cutting those. Just be sure to use thermocouple wire all the way to the controller.

[RaymondMillbrae]

But don't cut the thermocouple wire too short, as there are other benefits to this added length.

Yepper-ee...it doesn't have to be "mutually exclusively" used on your casting pot. If you keep it long, you could even use it as a thermometer on your smelting pot when casing your ingots.

In my opinion, don't cut it too short. Leave it longer and just coil it.

In Christ: Raymond

[kbstenberg]

I hope you dont mind me asking another question, If so please have a moderater deleat.
When attatchung the SSR to your project box. Should you cut a hole through the box so that the SSR makes dirrect contact with the heat sink?
Or can the SSR an heat sink just be in close proximitie to each other?
Kevin

[cheese1566]

Ask away!!! We are all here to help...
The SSR needs to be in direct contact, usually the back of the SSR to the flat of the heat sink so the heat from the SSR transfers to the heat sink. Think of the heat sink as a radiator. Wouldn't hurt to apply some silicone heat sink compound (not silicone caulk sealer!) to where the SSR and heat sink touch, helps in the transfer of heat.

[kbstenberg]

Thank you Cheese 1566
Kevin