Another PC oven surrenders to a PID ...

[OS OK]

Hossfly...One thing about that insulation is that is easy to cut and handle, it's really dense. It's 1" thk. & too thick to wrap the entire oven so Iam splitting it in half to cover the top and other side.

jsizemore... I understand this about recovery time using 2 sets of elements and I can put the second set on the bottom back in service if one set will not do, but...I want to try this and time it from a cold oven, full tray (about 175, 200 gn. cast).

While ordering a heat sink for the SSR, I ran across this chef's pocket thermometer & ordered it too...thinking that it can be mounted in the enclosure above the PID and I can see in an instant if this cooling fan is doing an adequate job of venting the enclosure or if something else is going awry...excessive heat is prolly the no.1 enemy of these solid state electronics.

[dave 45-90]

This is what I did
1. Wired the oven fan on separate plug.Runs all the time Ran RTD probe thru side center.
2. Kept the original plug on oven and tied it to my control module that controls lead pot. 2 Modules
3. Run the original thermostat as high as it will go. Mine goes to 450
4. Start timer and cook for desired time. RTD is controlling temp now. Not original thermostat Elements turn off and on and timer keeps running
5. Timer goes off and cools the product.
Simple Solution. Put up some photos
***Don’t bypass the original bimetallic thermostat. It will act as a high limit it something goes amuck
Nothing in oven was changed except convection fan to always run and hole for probe
The RTD module controls temp. Timer shuts elements off when timer has timed out and cool down begins

[OS OK]

This is what I did
1. Wired the oven fan on separate plug.Runs all the time Ran RTD probe thru side center.
2. Kept the original plug on oven and tied it to my control module that controls lead pot. 2 Modules
3. Run the original thermostat as high as it will go. Mine goes to 450
4. Start timer and cook for desired time. RTD is controlling temp now. Not original thermostat Elements turn off and on and timer keeps running
5. Timer goes off and cools the product.
Simple Solution. Put up some photos
***Don’t bypass the original bimetallic thermostat. It will act as a high limit it something goes amuck
Nothing in oven was changed except convection fan to always run and hole for probe
The RTD module controls temp. Timer shuts elements off when timer has timed out and cool down begins

Nice build dave 45-90...thanks for posting the pictures and description here.

I'm not so sure that the bimetallic strip can react as fast as the circuit breaker which senses current 'magnetically & thermally', so I have it covered in this manner. On top of that, the oven is on a GFCI circuit in the garage...I think, in the magnetic sense (current inrush from a dead short) the GFCI will react even faster than the circuit breaker in the house panel.

[dave 45-90]

We are not looking for overload condition, but an overheating of the oven..With my set up, you can walk away from oven and comeback cooled down. I dry my brass @ 150 powder coat and cast with the controllers. The axial fan in my little casting station works on it to

I'm not so sure that the bimetallic strip can react as fast as the circuit breaker which senses current 'magnetically & thermally', so I have it covered in this manner. On top of that, the oven is on a GFCI circuit in the garage...I think, in the magnetic sense (current inrush from a dead short) the GFCI will react even faster than the circuit breaker in the house panel.[/QUOTE]

[OS OK]

I'm getting more parts-n-pieces installed as they come in the mail...

The PID and associated wiring is back in after the insulation install, unfortunately there is not enough room for the small cooling fan for the PID, I wanted to mount it below there where I'm pointing...



Still waiting on the heat sink to come in and that'll tie up all the wiring.

I hated to do this but I'm mounting the fan on the outside of the enclosure where it will blow directly on the side of the PID...





Any smaller fan that would have fit inside, I doubt if it would deliver enough air volume to circulate in the whole enclosure and help cool the SSR too?



The insulation being 1" thick is too thick to cover the top and left side wall of the oven...I'm cutting it in half, down to 1/2" thick and it looks like I'll have enough left to insulate the whole rig...



That's all the progress for now...

[dave 45-90]

RTD modules are not ambient compensated. Kinda risky, but may be ok with fan

[OS OK]

RTD modules are not ambient compensated. Kinda risky, but may be ok with fan

That is the reason I am installing the pocket thermometer in the control enclosure just above the PID.
I hope to monitor that as I make PC'd cast and have good 'cool' results, if so...I can get more comfy with using this little oven set up this way.
It's kinda a challenge to see if I can get away with it.
If not...I'm shopping for a large digital oven & that will be the end of it all.

[dave 45-90]

Even with a digital oven you still[ need an SCR I use a 40A so no heat sink is needed

[cwlongshot]

I asked Willie about that and our response was simple... Open the lid.

I was casting this AM about 4 hours and it was not even too hot to touch. So warm at best.

But I trying to talk with him cause the temp dont match (or even close) to my thermo. Is it adjustable??

CW

[OS OK]

I asked Willie about that and our response was simple... Open the lid.

I was casting this AM about 4 hours and it was not even too hot to touch. So warm at best.

But I trying to talk with him cause the temp dont match (or even close) to my thermo. Is it adjustable??

CW

HEY THERE CW'b... Are you referring to the PID not matching the thermometer you have used in the pot? That the thermometer is way off?

If so, you can calibrate the thermometer to come much closer to the PID...I used a boiling pot of water, dipped it in (give it a little time to adjust, they're pretty slow to respond) and read it 45ºƒ too low on my Dillon thermometer. I held the bottom tube with pliers where it comes in contact with the round enclosure for the dial, twisted the dial housing to make the thermometer line up with aprox. 212ºƒ...now they are very close. I think back all the years I used the analogue thermometer and that I was that far off all that time. I was casting much hotter than I thought.
Can't find a good video (short-n-sweet) for boiling water calibration, here's a few to choose from.

https://www.youtube.com/results?sear...+boiling+water

I have recently seen a video of calibrating the analogue thermometer with a glass of ice water also...

https://www.youtube.com/results?sear...with+ice+water

All these videos are pretty 'corney'...you'll get the picture. I used boiling water because analogue instruments read closer to accurate towards the mid-range of their dials...ice water is too low to suit me but no doubt it works also.

[dave 45-90]

Bi-metallic will get u in ballpark. Nut on bottom on most can be turned holding the dial while in ice water. RTD offset can be calibrated to
Always remember this
I can have 2 guys measure a know media temp on a service call
They will always agree on the digital, never on the analog
Same with voltage
My Flukes have certified calibration once a year
You can put the controller on auto tune and once it learns the fuzzy logic, temps can be maintained within a 1/10 of
a degree
If you unplug controller or mess with it, control has to retune itself to what the target is.If it overshoots on power up. That’s the cause plus heat soak
These things think, long as no garbage in there will be garbage out.
If by chance you have an issue. Pm me
I live and breath this stuff everyday
That’s why I use RTD probes instead of 2 wire thermocouples
Course we aren’t maintaining Covid vaccine or biological samples in an evidence room

[OS OK]

Bi-metallic will get u in ballpark. Nut on bottom on most can be turned holding the dial while in ice water. RTD offset can be calibrated to
Always remember this
I can have 2 guys measure a know media temp on a service call
They will always agree on the digital, never on the analog
Same with voltage
My Flukes have certified calibration once a year
You can put the controller on auto tune and once it learns the fuzzy logic, temps can be maintained within a 1/10 of
a degree
If you unplug controller or mess with it, control has to retune itself to what the target is.If it overshoots on power up. That’s the cause plus heat soak
These things think, long as no garbage in there will be garbage out.
If by chance you have an issue. Pm me
I live and breath this stuff everyday
That’s why I use RTD probes instead of 2 wire thermocouples
Course we aren’t maintaining Covid vaccine or biological samples in an evidence room

The auto tune feature is what I especially like.
It will control more precisely than I would even worry about...it's a win - win in the melt pot or oven.

[dave 45-90]

If auto tune over shots on a regular basis , the gain can be adjusted. There is a lot more in most controllers than needed, but being able to adjust and watch the results is very satisfying. Least to me anyhow. Keep a log on changes so if you really screw it up, u won’t have to go back to the factory default. Don’t know where you are going if there is no record of where you’ve been

[dave 45-90]

As a rule. Control panel fans pull out rather than push in. The fan is more efficient on those applications where there is an inlet on the other side of panel Turbulence is caused within the enclosure and the warm air does not mix well with the fresh , thus it goes in circles

[OS OK]

As a rule. Control panel fans pull out rather than push in. The fan is more efficient on those applications where there is an inlet on the other side of panel Turbulence is caused within the enclosure and the warm air does not mix well with the fresh , thus it goes in circles

So much to learn, it's nice to have a pro here with such good advice. (I'm a retired Electrical Contractor but in my day programmable controls were new to the industry...can't recall how many hard-wired relay panels I've built and installed). The entire industry has changed like night and day.
Won't be long and I'll have some empirical data to offer up the way it is set up...waiting with baited breath and crossed fingers.

[dave 45-90]

So much to learn, it's nice to have a pro here with such good advice. (I'm a retired Electrical Contractor but in my day programmable controls were new to the industry...can't recall how many hard-wired relay panels I've built and installed). The entire industry has changed like night and day.
Won't be long and I'll have some empirical data to offer up the way it is set up...waiting with baited breath and crossed fingers.

U will be fine. Read the directions and set up. Make sure thermistor matches the correct offer on program. Sometimes it’s easier to program out and get practice rather than in oven in your case. You may be chasing the oven around pushing buttons Put the probe in crushed ice with a little water and make sure it’s reads +32F. If not you can adjust the offset in the program. Hylite the parts of the ladder diagram you used and or changed. Put the manual with your loading book for safe keeping. Don’t lock program

[OS OK]

U will be fine. Read the directions and set up. Make sure thermistor matches the correct offer on program. Sometimes it’s easier to program out and get practice rather than in oven in your case. You may be chasing the oven around pushing buttons Put the probe in crushed ice with a little water and make sure it’s reads +32F. If not you can adjust the offset in the program. Hylite the parts of the ladder diagram you used and or changed. Put the manual with your loading book for safe keeping. Don’t lock program

"10-4...will do, thank you Dave!"

[OS OK]

Got the insulation installed and the controls re-installed...it's TIME FOR A PRE-TESTING...before I load the oven with PC'd casts.

I loaded 5 pounds 15 ounces of small ingots into the tray to simulate the bulk of what a full tray might might weigh.
*(That would be about 180, 225 gn. 45 cal. RN's I run in the 1911.)
I am monitoring temperatures in both Cº & Fº (unfortunately, I can't make this PID read out in Fº)...
the PID monitors in the upper oven along with the Taylor glass thermometer...
the Multi-meter monitors below the oven tray and the control enclosure is monitored by a pocket thermometer within the enclosure.
I used an old iPhone as a timer so I could write down all the temps. as each minute went by...



The Multi-meter's thermocouple probe is an unprotected wire junction hanging under the tray...



Here are all the temperatures I recorded, minute by minute...



Before I changed all these controls, I used to time the process from when the PC had liquefied and added 20 minutes to that making a total bake time of 25 minutes.
(I can't remember what the temp. was inside the oven when the PC becomes liquid)...this matters now that I am only using the upper heat elements.
The other controversial issue is the temperature below the tray...it never rises above 260ļ. I am not sure this will be an issue or not as the casts above the tray are in full heat, I suppose I'd have to drill the base of one of the cast and put that Multi-meter wire inside to determine if this is going to be an issue or not?

Another issue is the PID reading 180Cº and the glass thermometer reading 400ƒº (the PID setting should be 204Cº) I guess I should check to see if the correct thermocouple is plugged into the values the PID uses...only problem there is that I don't have an ID# on that thermocouple!)

Another 'possible issue' is the control enclosure. It seems to be fine while the process is taking place...BUT...after the oven is off & cooling, that control enclosure rises to 140ļ.



That may or may not be a problem...BUT...this 'Chineeseium PID' does not have a rated temperature of operation printed on the device or in the instructions! Typical of all Chineeseium CrappoJunk we import in to the USA! (Whatever happened to the ANSI ~ 'American National Standards Institute'?)
If I remember correctly...all the controls I used to mount in control enclosures, relays of various sorts and magnetic starters, control transformers & such were rated for operation at 75Cº which is 167ƒº. If that is still true, I should be good to go?

Well...obviously, there's more work & testing to be done.
Do any of you have any comments or suggestions before I load the first PC'd tray of Lyman 452374's ... 225gn. - RN's?

[OS OK]

Test day today... going to see if I can get 3 full oven batches from the cast above, determine bake-time with the single heating element & whether or not the PC cures properly, especially on the base.

Back this afternoon hopefully with good news and an end to this thread?

[jsizemore]

I check my recovery temp after putting in a new batch in a preheated oven. When the temp hits 375F I start the timer. Cook time is 20 min. with PC. I use a single layer in each pan of wire mesh trays. That's about 12lbs of bullets between 4 trays because that's what fits in my large Oster 3 shelf. Bottom shelf has a steel sheet on it to act as a deflector so the bottom element doesn't over cook/melt bullets when it's on. I'm getting ready to do an Avantco 3 shelf 1/4 sheet commercial build. About the same current draw as the the home countertop convection ovens. Heating element surrounds the convection oven so less chance of hot spots in the cabinet.