Another PC oven surrenders to a PID ...

[OS OK]

It had to happen sooner or later.... thanks to Conditor22 and a generous surprise package that showed up this morning. He and I made a horse-trade for one of his spare Lee 10 pound furnaces. In that box he included a Rex C100 PID, a solid state relay, a thermocouple and a fuse enclosure...had no idea these controls were coming!
Thank you Jim, I appreciate this very much.

I decided to gut all the controls but the 'ON - OFF - Timer Set' switch and the pilot light. I removed the 'thermostat & dial temp. setting' and the 'selector switch' that selected the upper and lower heat elements and controlled the fan. I cut the lower set of elements out permanently and wired it back using the upper element only. It is a small oven, the upper elements are all I needed.

Everything tucked in nicely to the vented control area of the side panel...vents are bottom, side and back...

https://i.imgur.com/ClxJAPE.jpg

Only one test so far...as it is empty, 180ºC = 400ºƒ...

https://i.imgur.com/tb2Lrty.jpg

the thermocouple is in the rear on the right side 1.5" above the tray...

https://i.imgur.com/3wmye7L.jpg

Heated air is drawn into the fan across the top of the tray on the right at the same level the thermocouple is mounted and is blown out from the top slots between the elements and that is the circulation. Heated air also blows out the bottom slots between the now defunct lower elements to heat the tray from the bottom...

https://i.imgur.com/CUuZM5S.jpg

There was plenty room in the back area of the enclosure for the thermocouple and the solid state relay...

https://i.imgur.com/cEAbU3S.jpg

In the front is the PID...fan in the middle...

https://i.imgur.com/xWG8KoK.jpg

Only thing left now is to take another PID I have and put the thermocouple in the control area now that's now closed up and monitor the temperature there while in operation. I think these controls are rated at max. 75ºC/167ºƒ. If the control area exceeds that I will insulate the oven wall side of the enclosure and add a small fan to the rear to pull in fresh cool air. This should take care of any overheating of the controls.

https://i.imgur.com/lbSCOx6.jpg

After that, I'll load the tray full of 230 gn. 45 casts and find out how long I need to set the timer for a single batch starting from a cold oven.
I think I've pretty much covered all the angles but if one of you fellas see something I've overlooked, please bring it up in a comment.

[kungfustyle]

Nice job.

[Valley-Shooter]

"wired it back using the upper element only. It is a small oven, the upper elements are all I needed."

So you no longer have an oven, it's just a broiler now.
Not sure if you enough heat to warm the bottom of your baking tray/screen .

Sent from my Pixel 4 XL using Tapatalk

[joe leadslinger]

Geuss you didn't catch the fan part.

[Valley-Shooter]

Guess you didn't catch the fan part.Yes, I read that part, but where does it blow?
Across the top?

Sent from my Pixel 4 XL using Tapatalk

[OS OK]

Yes, I read that part, but where does it blow?
Across the top?

Sent from my Pixel 4 XL using Tapatalk

(copied from the first posting...)
Heated air is drawn into the fan across the top of the tray on the right at the same level the thermocouple is mounted and is blown out from the top slots between the elements and that is the circulation. Heated air also blows out the bottom slots between the now defunct lower elements to heat the tray from the bottom...

Take a look at a convection oven sometime, the fan system works the same in every one. I used a cigarette to determine this. Smoke drawn in at the center and ashes blown off at the extreme slots top and bottom, between the heating elements where the air increases heat before it once again is drawn in across the top of the tray.

My BROILER as you call it will do just fine as it used to cycle too much during a batch and overshoot the setting using both elements top and bottom. You might notice again, I've tested it once already...less than 5 minutes the PID was up to temp. from a cold oven...

https://i.imgur.com/QLlldB7.jpg

Before I run a full tray and get the timing correct, I am waiting on an insulation blanket and a cooling fan I ordered off Amazon.
I'll post results then.

[oley55]

With the PID controlling the temp, what was/is the down side of keeping both heating elements? My PID will cycle almost continuously once up to temp while the two elements quickly get my oven/boolits up to temp. Have you noticed a longer heat time?

[Valley-Shooter]

OS OK,

Thanks for posting all the pics. Never see someone mount the pid in the oven .

My toaster convection oven just went bad. thermostat not controlling max heat.

So I'm looking to rewire mine with a pid.

Sent from my Pixel 4 XL using Tapatalk

[OS OK]

With the PID controlling the temp, what was/is the down side of keeping both heating elements? My PID will cycle almost continuously once up to temp while the two elements quickly get my oven/boolits up to temp. Have you noticed a longer heat time?

The downside was two fold...first, the bimetalic strip/contacts that ran the two elements was very sensitive to staying put where it was set. It was very insensitive to keeping a constant temperature as it would open the heat circuit and allow the oven to drop to around 365 ~ 375ºƒ before it would close again. When closed it would open as much as 20 ~ 25ºƒ above the setting desired, 400ºƒ. A never ending battle to keep it right, many times having to watch the cycle to make sure things were OK in the oven.

Second..having two elements top and bottom create a heck of an overheating 'radiation' of the heat when they were on, too close and you can feel the searing heat. Those suckers would glow red as the thermostat cycled. In the end my PC'd cast were being cured from say 375ºƒ anywhere up to 425ºƒ, not hardly a constant oven environment. Several times I've caught it as high as 450ºƒ because the temp. adjusting knob got bumped and I didn't know it.

My tray used to be placed on the slot above where it is at in this picture...

https://i.imgur.com/CUuZM5S.jpg

That way it was about midway between the two raging red elements as they heated. The way it is now the tray is lowered away from the upper element and subject to a little less harsh temp. swings as they heat up.
The intention is to make less harsh the temp swings using the PID...it will bring the oven up to temp (empty) in less than 5 minutes, the elements above do glow red but I can't avoid that other than dropping the tray farther from them. Sorta like standing a couple feet farther from a campfire where you don't feel the searing heat yet your still warm against the cold night air.

When the PID is up to temp. it will sit there and flicker on and off in very short duration as it maintains the oven at 400ºƒ. This type of cycling is fine by me because the elements never are on long enough to glow red. The old system had too wide of 'on and off' variation and allowed the elements to glow red every time it was trying to maintain the set temp.
One element should, I think be better...may take a few minutes longer to bring a full batch of casts up to the temp. where the PC melts and the true timing would start but this is not important to me.

I am in no hurry as while an oven of PC'd cast are curing, I'm on one of the pots casting.

People get used to what they are doing with an unmodified oven and then start thinking that their way is the only way when in actuality, many of them have no idea what is going on inside the oven as far as temperature swings or temp. values are...all they understand is the markings on their knob, set to 400ºƒ and walk away...there's plenty proof of this floating around, I don't imagine too many are honest enough to post their mistakes and fess up to it.

https://i.imgur.com/DicLFSH.jpg

https://i.imgur.com/lFKdLi5.jpg

All I am trying to do is coat my cast and do a fine job of it...if it takes a little longer...so be it.
Once I have the other parts-n-pieces here and the final work is done, I'll be casting and coating again and I'll post to this thread the time it takes. If one set of elements won't do the trick, I have the bottom elements I can put back into the circuit. No harm no foul.

[OS OK]

OS OK,

Thanks for posting all the pics. Never see someone mount the pid in the oven .

My toaster convection oven just went bad. thermostat not controlling max heat.

So I'm looking to rewire mine with a pid.

Sent from my Pixel 4 XL using Tapatalk

If your controls are on the side of the oven be fore-warned that this compartment will get almost as hot as the oven inside. You have to insulate that oven wall between the control compartment and the oven. I am also adding a computer cooling fan.
It would be much simpler to put your PID in a separate box, this way you can use the same PID for oven or pot.
I am doing it this way only to keep the controls within the oven, in my old'demented view of things, it looks better and I don't have more equipment to deal with in an already overcrowded shop.
This is what I've ordered to insulate that side of the oven and as a little extra insurance, I'll install the cooling fan too.

https://i.imgur.com/femLLmy.jpg

[cwlongshot]

Thats awesome Charlie!! Great writeup too. Did ya do a video??

Willie Bulletman made me a PID last month and I finally got it installed yesterday. (Video is up)

Love ta see!

Im ordering a couple
More thermo
Couplers as I run three pots and two ovens. ;)

CW

[OS OK]

Thats awesome Charlie!! Great writeup too. Did ya do a video??

Willie Bulletman made me a PID last month and I finally got it installed yesterday. (Video is up)

Love ta see!

Im ordering a couple
More thermo
Couplers as I run three pots and two ovens. ;)

CW

No CW'b, no video...I am burned out on shooting/editing videos. Today a picture is what you get from this old'Lazybones.
I thought I saw your video when it first came up, nice package...portable and all.
Question...? Is the SSR connected to a heat sink. I think they will go out prematurely if they can't bleed off the heat. I thought that box the PID is in was plastic is why I asked.

Here is the video we are talking about...


https://youtu.be/R0Get_bvJAk

[fivegunner]

Wow thats a great job, I think I will build one like it, Thank you for sharing

[Cast10]

Wow! Super custom install! I like it!

Fixing to build mine for melting pot.......

[OS OK]

Wow thats a great job, I think I will build one like it, Thank you for sharing

Please see post number 10 and my warning regarding building controls into the side of the oven...

charlie

[Hossfly]

The most accurate way I’ve found to sense the temperature of a boolit is a way another member showed, (Slide)IIRC. Take the boolit you intend to cure and drill a hole to the center, place the thermocouple tip into it, close with glue or epoxie, or just smash to hold in place. I use several of these and a separate thermometer to monitor the temp of boolits I’m curing. The PID units are 100% way to go, and are very inexpensive. You did an excellent job on converting yours.

Just another way to check temp and monitor that process. Some convection ovens come with pretty good controls. Mine controls at 400 when set at 425, with all original equipment. I would convert if it didn’t. I have melted ingots on my hot plate thinking I was just keeping them hot for adding to pot.

[OS OK]

The most accurate way I’ve found to sense the temperature of a boolit is a way another member showed, (Slide)IIRC. Take the boolit you intend to cure and drill a hole to the center, place the thermocouple tip into it, close with glue or epoxie, or just smash to hold in place. I use several of these and a separate thermometer to monitor the temp of boolits I’m curing. The PID units are 100% way to go, and are very inexpensive. You did an excellent job on converting yours.

Just another way to check temp and monitor that process. Some convection ovens come with pretty good controls. Mine controls at 400 when set at 425, with all original equipment. I would convert if it didn’t. I have melted ingots on my hot plate thinking I was just keeping them hot for adding to pot.

THANKS FOR THE TIP's.

You know, I got this oven back when I joined up here on CB's site and PC was already the 'new-thing' and developing. Like others I was happy with lube-sizing but this PC thing looked awful good to me. I go to K-Mart and buy the cheapest 'convection oven' they had...it was small also so I am limited to say 180, 45cal, 230 gn. casts...small batches like this is not really a problem.
BUT...
If I had it to do over again I would have spent the extra money to find a digital oven, If I had I wouldn't have had all the trouble I have been through up to now. Sometimes the right tool in the long run...is not the cheapest.

Something I've seen some friends do is locate an electric wall oven that is being pulled from a remodel in a kitchen and put that on a small piano type dolly, wire it with a welding 230VAC single phase plug so they can use an already existing outlet in their shop and use the wall oven for PC work.
They often fabricate various parts and pieces in their welding projects and they like the option of having them PC'd rather than a rattle can of paint.
You can coat a pretty good size object in an old wall oven.

[OS OK]

The Ceramic blanket and the cooling fan came in today, got a little more done towards an end.

Had to remove the PID & SSR & thermocouple to install the insulation...

https://i.imgur.com/urxFFto.jpg

It will probably be next week before the heat sink & thermal paste for the SSR gets here, then I can put it all back together.
Never used this type insulation before, spun ceramic or some such...

https://i.imgur.com/CFFj8vd.jpg

feels weird to the touch so I followed precautions and wore the whole safety thing ~ eye, breathing & hands. I guess I'm getting too old to flirt with having any more ailments than I have already.

More to come soon.

[Hossfly]

OS OK, you are wise to head those cautions, I’ve worked with that insulation doing boiler work for 30+ years and still do. When I just look at it I start coughing. Still have several rolls of it in my shop. Very good high temp insulation, was used on back doors of boilers for turn around of flue gasses.

[jsizemore]

Recovery time is greatly improved with the 2nd element running. I use insulation like you but on a large Oster. I mount the SSR directly over the vent slots at the back. I've got 2 shelves so my 8" thermocouple probe is through the opposite wall from the convection fan. With all the insulation I haven't had cabinet temps in the control area be a problem but that circulation fan for that area will add a much longer life to your PID not to mention more accuracy in your oven temps.

[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.

https://i.imgur.com/uFaCFOk.jpg

[dave 45-90]

287954This 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]

287954This 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...

https://i.imgur.com/DJ6slPT.jpg

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...

https://i.imgur.com/vdF5dxS.jpg

https://i.imgur.com/2LnBNEH.jpg

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?

https://i.imgur.com/iuwetK8.jpg

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...

https://i.imgur.com/FxnyE1z.jpg

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. :razz:

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. :razz:

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?search_query=calibrate+a+thermometer+with+ 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?search_query=calibrate+a+thermometer+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...

https://i.imgur.com/RGHkiCg.jpg

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

https://i.imgur.com/rrhYpOI.jpg

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

https://i.imgur.com/iQIHMW2.jpg

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.

https://i.imgur.com/PPuTKfn.jpg

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?

https://i.imgur.com/L0PCygD.jpg

[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.

[OS OK]

Final testing & I think I have a workable oven... Several questions have 'sorta bothered' me up until now...
*Will one set of heating elements in the top of the oven be enough to bring a full tray to full temp & in a timely fashion?
*Will the delicate PID survive in the control enclosure doing several batches of cast?
*What will be the new bake time starting from a luke warm or cold oven?

I guess, first things first. I need to see if the 204çº temp setting on the PID will agree with my multi-meter reading 400ƒº? I have a reason to want to use the multi-meter.
I cranked it up, empty, and allowed the PID to come to the set temp (with fingers crossed) and it came out close...the control enclosure with the cooling fan running is at a cool 83ļ.

https://i.imgur.com/RGY2YhJ.jpg

Here's why I wanted to use the multi-meter. Many times the question has come up in the past whether or not the interior of the cast boolits come up to oven temp. and does that affect the quality of the coating getting cured? I have no idea but I'm going to try to answer that question of inside temperature of the cast.
I drilled the bottom of one of the cast so that I can insert the wire end of a thermo-couple.

https://i.imgur.com/k5GLUJU.jpg

Inserted the wire and set the cast on it to see if it would stay put? That wire is springy...

https://i.imgur.com/6vt66dU.jpg

So far...so good. Next, to shake up some Lyman 452374 - 225gn. RN's in my 'old lead' blend of PC...

https://i.imgur.com/QOWq6AT.jpg

Start stacking the first full tray of 3 that I will bake back to back today...

https://i.imgur.com/MX2Bnkt.jpg

Loaded the tray and the bare cast with the wire stuck in it's tusch...started the timer running.
**Notice that I almost never get a picture with the PID's numbers fully lit up. I think they blink and at a rate that doesn't agree with shutter speed of this digital camera? Maybe someone has the answer to that, I don't. I have to actually take a short video if I want to show a picture of those numerals lit up & then take a screenshot to show them...a big pain in the tusch!

https://i.imgur.com/8Trn8YT.jpg

So far so good again...next thing to monitor is the time elapsed when all the cast's PC coatings has turned to liquid? It's 5 minutes, just as before I started this project...

https://i.imgur.com/xq7vR4R.jpg

The interior of that bare cast is already up to 266ļ... (first mistake...I forgot to write down what the actual oven temp. was!) "Oh well!"

It was about 9:30 minutes when I noticed that the interior oven had come up to 204çº (400ƒº) from this point I add 10 minutes bake time and I think I now have 20 minutes total for the cycle time? I switched the on-off/timer switch at the bottom to auto-off and set the timer to 10 minutes...the oven should turn off after a total of 20 minutes.

https://i.imgur.com/7tkSCpe.jpg

The PID had overshot and gone up 207çº (the PID is learning for the first time with a full tray of lead) by now the bare cast's interior is up to 367ƒº...

At 20 minutes I expected the bell to 'ding' signaling the end of the cycle, the oven actually turned off at 22 minutes. The interior of the bare cast has settled to 361ƒº and the oven was at 204çº (400ƒº) . . .

https://i.imgur.com/DeepmnN.jpg

I pulled this first tray out and allowed them to cool a few minutes and dumped them and started loading another tray of 3 trays total. I wished I had an extra tray to alternate with but I don't and can't find one to fit this oven..."Oh well."

https://i.imgur.com/TRS0ymN.jpg

While they sat there and cooled, the control enclosure fan is off, the temp. in the enclosure rose to 120ļ, that is less than the first time I tested it but today is a mild day of 78ļ in the shop, even after the third tray came out of the oven the control enclosure never rose above 120ļ.
It is looking like I now have a PID controlled oven and that it just may last a while (fingers crossed again!).

Thanks for following this project boys...it's been fun...

[Hossfly]

Excellently good results, what I did with that boolit with the hole and thermocouple was just tap down with a hammer or squeeze with pliers or vice to hold secure. Use several different size boolits to suit what your cooking.

[OS OK]

Excellently good results, what I did with that boolit with the hole and thermocouple was just tap down with a hammer or squeeze with pliers or vice to hold secure. Use several different size boolits to suit what your cooking.

Thanks Hossfly... I did consider flattening the cast a little to hold that wire in place but I thought I might damage the junction trying to get it back out. If I had done that I would have to trim it off and 'silver solder' that junction back together. I didn't have any silver solder to do that with so...out of laziness I just did it the easy way and hope for the best.

[oley55]

as per Hossfly's previous advice to me, I bought a handful on inexpensive thermocouples and I now have a dedicated bullet/thermocouple for nearly every bullet I cast/pc. for those that are very similar in shape n weight a real close is good enough.

I let my pid control the oven, my thermocoupled bullets dictate when my cook time begins. When the bullet reaches 400, the clock starts every time, for every batch. Probably overkill, but one less thing to wonder/worry about.

[dave 45-90]

Nice job. Success on a new endeavor so rewarding

[oley55]

OS OK,

Although my PID is from Auber, I was able to change it from C the F. I did some searching and the consensus of many is the REX-C100 can not be made to use F. I found this questionable and searched a bit more and found this youtube video showing the steps for switching to Fahrenheit. https://www.youtube.com/watch?v=UETVv0qgz-w&t=1s

It has been several years since I changed mine, but the process seems to be identical or very similar, (but then my memory ain't what it used to be). To bad these devices will not easily tell you whether it is set to C/F with a visible C or F.

Also an FYI on thermal couple thermometer devices. I have an older Greenlee DM55 multi-meter with K type temp option. For reasons unclear it NEVER matches my single purpose device or my PID readout. At room temp using the same thermocouple it was consistently reading 6 degrees below the other two which were only 0.2 degrees different from each other. For what we are doing a 6 degree variance is probably not an issue, but rather just something to be aware of.

Edit added: if you do try setting your PID to F, I hope you share your results. I am holding off buying components to build two additional PID controllers and find the eBay $18-$23 dollar REX C100 package deals (including separate SSR and heat sink) very attractive price wise (if they'll do F) versus the $43 Auber units which seem to have way more functions than we need for just controlling temps.

[OS OK]

OS OK,

Although my PID is from Auber, I was able to change it from C the F. I did some searching and the consensus of many is the REX-C100 can not be made to use F. I found this questionable and searched a bit more and found this youtube video showing the steps for switching to Fahrenheit. https://www.youtube.com/watch?v=UETVv0qgz-w&t=1s

It has been several years since I changed mine, but the process seems to be identical or very similar, (but then my memory ain't what it used to be). To bad these devices will not easily tell you whether it is set to C/F with a visible C or F.

Also an FYI on thermal couple thermometer devices. I have an older Greenlee DM55 multi-meter with K type temp option. For reasons unclear it NEVER matches my single purpose device or my PID readout. At room temp using the same thermocouple it was consistently reading 6 degrees below the other two which were only 0.2 degrees different from each other. For what we are doing a 6 degree variance is probably not an issue, but rather just something to be aware of.

Edit added: if you do try setting your PID to F, I hope you share your results. I am holding off buying components to build two additional PID controllers and find the eBay $18-$23 dollar REX C100 package deals (including separate SSR and heat sink) very attractive price wise (if they'll do F) versus the $43 Auber units which seem to have way more functions than we need for just controlling temps.

Just sent you a PM in reply to yours, I appreciate the effort to help me with that.

I knew that about the DVM temp probe being different, it ain't much to worry about for us PC'ers.

When I buy for another build it will be another MYPIN like my pot controller...

https://i.imgur.com/pA5NYeo.jpg