PID controller

[Dragonheart]

Good deal You know, some people on here are smarter than they look LOL

Dragon, good idea with the fans, I use a case fan to keep the motor cool on my DIY case polisher

Yes, I did the same on my wet SS pin case cleaner by installing a salvaged fan out of an old vent hood. It blows air through the salvaged washing machine motor that now runs so cool you can put you hand on it. I built my cleaner then found it only takes 10 minutes to clean 3/4's of a gallon of cases to like new appearance so it's not like the motor runs long enough to overheat. Heat is the enemy of electronics so it doesn't hurt to do an overkill on cooling or at leas that is my excuse.

[Vettepilot]

Hey guys. Help!?

In order to do salt bath annealing, and to make lead casting easier/nicer, I finally bought a PID. I have had great luck with Banggood, so I bought one from them.

I chose one that said "0 to 999 degrees C". After the requisite 3 week shipping time, it arrived and I was excited..... until I opened it and it says "0 to 400C". Bummer, that might just barely work for casting, but not for the annealing. (500 to 550C)

The unit says "AKC REX-C100". Does anyone know if this will work for the higher temps???

https://www.banggood.com/100-240V-40..._warehouse=USA

Thanks in advance,
Vettepilot

[Vettepilot]

I do understand that at the very least I will need a higher temp thermocouple.

Vettepilot

[JonB_in_Glencoe]

you should be able to change temp range in the parameters

https://www.mpja.com/download/rex-c100.pdf

[Vettepilot]

Thanks! I would never bother sending a 12 dollar item back to China; but what bummed me out was possibly having to wait another 3 weeks to get the correct one. As it is, it looks like it will cost me another 10 bucks just to get the right thermocouple in a reasonable time!

Oh well, so goes the commerce with China... My fault I suppose. I would love to only buy American made, but just do not have the bucks for the inflated prices, and so many things aren't made here anyway!

Vettepilot

[Dragonheart]

In the photo the side panel on the PID says 999C? What you received is different?

You might want to look on Amazon for something you can get in 2 days or at least return.

[Vettepilot]

Yeah, the photo still show 999c but the rest of the ad copy has been changed.

Maybe it will work, with a better thermocouple. We'll see....

Hey, we know it is a bit of a "roll of the dice" when ordering China direct, but I've got a bunch of things I could not have afforded otherwise. So, I am still way ahead!

Thanks,
Vettepilot

[Dragonheart]

Yeah, the photo still show 999c but the rest of the ad copy has been changed.

Maybe it will work, with a better thermocouple. We'll see....

Hey, we know it is a bit of a "roll of the dice" when ordering China direct, but I've got a bunch of things I could not have afforded otherwise. So, I am still way ahead!

Thanks,
Vettepilot

I personally would get another PID as I would think this one will just not read above the spec regardless of the thermocouple, but who knows?

[RedlegEd]

Yeah, the photo still show 999c but the rest of the ad copy has been changed.

Maybe it will work, with a better thermocouple. We'll see....

Hey, we know it is a bit of a "roll of the dice" when ordering China direct, but I've got a bunch of things I could not have afforded otherwise. So, I am still way ahead!

Thanks,
Vettepilot

Hi Vettepilot! I did the same thing, using a PID for both my salt bath annealing and casting pots. Because I use the same PID for several applications, I ordered these thermocouples from Amazon. You get 5 for $10 shipped free with Prime. The upper limit is 482°C (900°F,) which is fine because that's the max temp I use to anneal my brass, and well below casting temps. I make thermowells from 1/8" aluminum tubing I get at Michaels or Hobby Lobby, and these go directly into the lead or salt bath (I made a separate one for each pot.) It sure makes annealing and casting a whole lot more precise when you can control your temps. Ed

[Vettepilot]

Hmmm, I had never thought about making my own sheath/well. How do you seal the bottom?

Thanks for the link. Here's the one I was going to buy:

http://www.amazon.com/Thermistor-Tem...-24-spons&th=1

Vettepilot

[Vettepilot]

It seems from reading the directions, that the default setting on this unit is 0 to 1372F degrees. I think....

The "translated" instructions leave MUCH to be desired. If anyone has direct experience with this exact unit, please let me know. (AKC REX-C100)

Thanks,
Vettepilot

[dave 45-90]

Made my enclosure out of 16 ga. aluminum and covered with holographic foil paper

[RedlegEd]

Hmmm, I had never thought about making my own sheath/well. How do you seal the bottom?

Thanks for the link. Here's the one I was going to buy:

http://www.amazon.com/Thermistor-Tem...-24-spons&th=1

Vettepilot

Hi. I was looking at that kind first, but then decided to go with my own since I was using it across four casting pots and an annealing pot. Also, I'd only get one for $10, vs getting 5 for $10. Here's what my controller looks like (though not nearly as nice looking as dave_45-90's box.) I added the simple K-type socket to the case to accept Thermocouples with plugs. To seal the bottom of the sheath/well, you just pinch it closed and fold it up twice using needle-nose pliers. You push the sensor tip down to the bottom, then crimp the top to hold it in place. I use a simple bracket to hold the probe in the casting/annealing pots. Ed
Attachment 240442 Attachment 240443 Attachment 240444Attachment 240445

[dave 45-90]

Mine plug in with 3 pin shielded connectors. That way I can use RTD's or thermocouples. Response is better with little overshoot with RTD's direct immersion. Auto Tune will learn the parameters quickly and control precisely. Proper control setup is the key success
Setting up upper and lower ranges are important to minimize dead band
I use 40 amp SCR's, so there is no heat what so ever generated.

[RedlegEd]

Hi. I've not had much trouble on the casting side, as the thermal mass of the lead (especially in a 20# pot) allows the PID to maintain a pretty consistent temperature. The biggest issue I've had is with the annealing pot (Lee 10# Melter Furnace.) Even with the auto tune of the PID, there just isn't enough thermal mass of the molten annealing salts, nor is there enough power in the pot's coil, to stabilize and maintain a temperature of ~900°F while annealing brass. While the PID is providing almost 100% power, I can easily outrun its ability to maintain the temperature by rotating a new case every 6-7 seconds...it goes down even faster if I double up. Starting at ~900°F, I can get approximately 15-20 cases done (depending on the size,) before the temperature drops down to ~870°F. I'll then need to wait a few minutes while the heating coil in the pot struggles to get it back up to temp. The only time I get this when casting is when I dump sprues back in, or freshen the pot with more alloy. Ed

[dave 45-90]

I found that insulating the outside of pot helps control and maintain temperature better. Without direct emersion nickel alloy heaters and RTD's, the temperature curve can look like the Rockies. There is just to much led and lag when a load is applied. Dunno how your setup looks, but I am going to make a direct immersion melting pot that will handle any load.
The secret to control of process, is getting the media in close contact with the output and input of said process
Wells and thermo mastics, coil heaters on outside of pot, are bunk for precision control work.
The sensors can be set up in multiples for averaging the process over the given volume area

[RedlegEd]

I found that insulating the outside of pot helps control and maintain temperature better. Without direct emersion nickel alloy heaters and RTD's, the temperature curve can look like the Rockies. There is just to much led and lag when a load is applied. Dunno how your setup looks, but I am going to make a direct immersion melting pot that will handle any load. The secret to control of process, is getting the media in close contact with the output and input of said process
Wells and thermos mastics, coil heaters on outside of pot, are bunk for precision control work.

Hi Dave. You bring up very good points, and for the most part, I agree. My casting setup is as posted in #33 and below, which I think is pretty normal for folks who use standard commercial production type pots with an internal heating coil (e.g. Lee) when casting bullets. In building my setup, my goals were functionality, flexibility, and economy. While a high degree of precision would be nice, it is not as important to me as the other goals. As you can see in the picture below (this pot is for 20:1 alloy,) I chose to immerse the thermocouple (protected by a casing) directly into the media (lead alloy.) The temperature measurements by this arrangement and control afforded by the PID are more than sufficient to provide a very good, stable result for casting bullets. Although I could definitely make the system more precise by incorporating the items you mentioned, at what cost for five pots? I do like your suggestion of insulating the annealing pot, but I'm afraid the lack of thermal mass will still cause problems. Ultimately, this is much like making homebrewed beer or smoking meat...I believe you can produce excellent results without spending a large amount of money on high end equipment to give you a higher than needed control precision. Ed

Attachment 240461

[dave 45-90]

I wrapped my pot with ceramic insulation blanket using water glass cement
You are right about where one stops on precision
I do control work, so I really like to tinker
I do think one can not get to much precision on powder coat baking
Trying to rely on an infinite control switch to control precision temperature is slim to none
And I think both left town

[RedlegEd]

Cool! Thanks for the information. Ed

[dave 45-90]

Cool! Thanks for the information. Ed

To bad we aren't closer. I could make a high output recirculating heated bath for annealing
I have a high temp magnetic drive pump somewhere around here in a junk pile
Add some meatal mesh screen to outside of blanket and paint with water glass cement
The insulation is fragile, but once set up it's pretty nifty
Be careful with the cement
Sodium Silicate is really irritating to skin