Toaster Oven Capacity Rules?

[slide]

Aren't you still measuring the temp of the air? With the thermocouple system you are getting the temp inside the bullet. I have been using the thermocouple for a couple of years now. I do hi-tek and powdercoat. My bullets are better doing it this way. Again, thanks to Ausglock who dreamed this up. He is the tester for hi-tek and has probably coated more bullets than anybody on the planet.

[OTShooter]

As I said, my bullets baked fine. If I was “pushing the envelope,” I might need the extra precision of a thermocouple cast into a bullet. But if that was the case, I’d probably also opt for a PID wired into the oven too. I’m just getting started, so just knowing that the oven’s interior is at the right temperature to start with is enough.

[Phlier]

I'm up to 20 lbs of boolits per batch, and my oven is still keeping up.

[Dragonheart]

As I said, my bullets baked fine. If I was “pushing the envelope,” I might need the extra precision of a thermocouple cast into a bullet. But if that was the case, I’d probably also opt for a PID wired into the oven too. I’m just getting started, so just knowing that the oven’s interior is at the right temperature to start with is enough.

The thermocouple is so easy to make. I like doing it with a 45 caliber as that is the biggest bullet I cast. Just open the spue on a hot mold and put the end of the wire into the middle of a cavity, then pour in the hot lead. If it is not what you want then put it in the pot and melt off then start again. Of course if you have a helper it is easier.

I think PID's are great, but don't see the need for putting a PID in a good oven. If the oven is up to and will hold the temp then all you need to know is when to start timing. The bullet/thermocouple will tell you that.

Another thing is the bullet thermocouple can show which areas come up to temperature last and that is where you want to start timing.

[OTShooter]

I see what you’re saying. I’m just not anywhere near needing to know how quickly the inside of a bullet gets to what temperature. I want to keep this - for the moment, anyway - as a “set and forget” sort of process.

I posted this because I was concerned that I’d missed something about how many bullets it took to max out an oven.

I have the oven pre-heated, leave the bullets in for 20 minutes, and the powder has cured fine. I’ve run 60 230 grain bullets at a time and not had paint problems.

When I start casting 120 grain 9mm bullets, then I’ll be able to get a whole lot of bullets in the pan, and then I may have to worry about capacity.

[Dragonheart]

I would agree in a preheated oven 20 minutes should work fine for pretty much whatever you can get on a single rack.

[GregLaROCHE]

I bake 400-500gn boolits for 35 minutes at 400*F staring with a cold oven. They always come out fine. Maybe I could save some electricity, if I experimented with less time, but for the time being this works for me.

[OTShooter]

I would agree in a preheated oven 20 minutes should work fine for pretty much whatever you can get on a single rack.

I let it preheat for “around 15 minutes”, but I have an oven thermometer in it while it’s preheating, so when I check it “around 15 minutes” later I know it’s up to temperature.

Right now I’m still getting used to how to put the bullets on the pan without goobering them all up, but I’m pretty sure I can get at least 80 of these 0.452 bullets on the flat pan I have. I’ll be able to get a bunch more 9mm bullets on the pan. I’ve read of people who just dump them on their rack or pan, but I want more experience in spacing and such before I get that blasé about it.

Just curious: where in Katy are you?

[Dragonheart]

I let it preheat for “around 15 minutes”, but I have an oven thermometer in it while it’s preheating, so when I check it “around 15 minutes” later I know it’s up to temperature.

Right now I’m still getting used to how to put the bullets on the pan without goobering them all up, but I’m pretty sure I can get at least 80 of these 0.452 bullets on the flat pan I have. I’ll be able to get a bunch more 9mm bullets on the pan. I’ve read of people who just dump them on their rack or pan, but I want more experience in spacing and such before I get that blasé about it.

Just curious: where in Katy are you?

I use bakers cooling racks to space my bullets and hold them upright while transfering to the oven. I find a reck where the grid square is close to my caliber size kike 45, 9mm, 30 caliber, etc. Once in the oven, I lift the rack off and load up another tray.

I have tried the dump method and it doesn't work for me as it leaves marks on the bullets, the bases are not completely flat and the coating flows in the direction of gravity. When I load and when I shoot I want to know that I have loaded the most accurate ammunition I can. If I start off with an imperfect projectile that I could have made better then I haven't done that.

I am one and a half miles south of I-10 just off of Fry Road, about 25 miles West of downtown Houston.

[Dragonheart]

I bake 400-500gn boolits for 35 minutes at 400*F staring with a cold oven. They always come out fine. Maybe I could save some electricity, if I experimented with less time, but for the time being this works for me.

I certainly would not cut my time down. Depending on the oven's power, seal, insulation, etc. without a load can take as much as 20 minutes to come to temp. When a load is added the energy is being absorbed by the bullets, trays, etc. It is going to take longer but the question is how much? This is my whole point, you can go with your best guess and as long as everything remains the same eventually find the cure point by trial & error. Or you can measure using a thermocouple and find the cure point regardless of changes in the load.

[OTShooter]

I see your point. Once I have some more bullets to mess with, a thermocouple may be helpful.

My in-laws used to live in Grand Lakes until they moved to Richmond. Now they’re in Florida, and I don’t get out your was as much.

[prs]

I get my boolits coated in bulk, either in plastic container or (now) in my Thumbler's Tumbler with airsoft. Then I line my converction toaster over with the non-stick foil. Then I place as many powdered boolits (typically 250g 45 Colt) as I can per tray without the boolits touching. Nitrile mechanic gloves lightly powdered with same paint powder works GREAT to place without bald spotting boolits. I stand them upright. My oven accomodates 2 trays and I use both. I have not bothered to count the total, I just do as many as it will hold. It takes a little more bake time, but not much. I established my time by watching them bake until the coating is glossy liquid paint then 15 minutes more. I am sure the convection feature helps me avoid hot spots, I get a nice even coating no matter where on the tray or which tray; all the same. While one ovenfull bakes, I am setting up two more trays of powdered boolits. Goes very fast.

prs

[BrutalAB]

...You can overload the racks weight supporting capacity... it makes a big mess.... and happens when youve spent enough time placing boolits that you want that particular toaster oven to meet mr sledge hammer.
I stopped trying to maximize my bakes after that.

[Dragonheart]

...You can overload the racks weight supporting capacity... it makes a big mess.... and happens when youve spent enough time placing boolits that you want that particular toaster oven to meet mr sledge hammer.
I stopped trying to maximize my bakes after that.

You are absolutely right, or at least what I found out the hard way with my new Hamilton Beach Countertop Convection Oven which had wider and weaker racks than my old HB oven. The factory racks were just too weak to support the weight of a fully loaded tray of bullets. Fortunately when they collapsed the powder had just started to flow, so nothing but my time was lost. I would suggest putting a trial weight on a rack before going for fully loaded trays to make sure it will hold the weight. I would also suggest casting a thermocouple into a bullet to monitor the temp on multiple trays.

My solution was to build two reinforced trays and reinforce the two OEM trays. Actually, an easy job for a TIG welder and a little scrap rod. I guess it's time time to load it up the newer HB and give it a run for the record. For those saying Why? Well it's like the "Mountain", if you have been doing this since 2012 as I have, then just turning out bullets has no challenge. Turning the process into a game makes it enjoyable.

[kevin c]

My understanding is that the coatings (HiTek for me, I'm guessing the same for PC) need the right temperature for the right time to cure right. My understanding of ovens is that they are insulated boxes that a heat source puts heat energy into, which then gets used to cook beef, buns and boolits.

Preheating the oven puts enough heat energy into the box to warm it to the set (air) temperature, then the thermostat cuts off the heat source, turning on again only when the temp drops below the set point.

Putting boolits into the heated oven drops the temp because each is a little cold heat sink that moves heat energy from the box into the metal. The more metal, the more heat gets taken and the more that needs to be replaced by the element to bring the box temp back up. The boolits warm up as they take in radiant heat energy from the heated walls and element and conducted energy from the air, but will only cure when enough heat has been absorbed to get to the curing temperature.

For a big load of metal, to get enough heat into them to cure the coating, there seem to be a few options:

You can start with a very hot oven, well over curing temp. That may shorten the time, but air, being very low density, can't hold all the heat needed, you don't want the walls of the oven glowing red, and you don't want little molten blobs of boolit alloy on your tray.

You can store extra heat energy inside the box by having a heat sink that will give up its heat to the air and then the boolits, like a brick, or pieces of metal.

You can increase heat input with a bigger source, like in a regular oven's big elements versus the little ones of table top toaster ovens.

You can circulate the oven's air, which doesn't increase the heat energy, but does speed heat transfer.

You can increase the bake time to give the heat source longer to input the energy needed.

I do 5 1/2 pounds of casts in my table top convection oven, regardless of boolit size, using the same oven setting and time for all. Maybe not exactly equivalent from small to big, but I figure the heat needed is pretty close to the same. I could try more, but then I might run up against the oven's limited ability to put in enough heat. Then I'd have to increase the time by trial and error.

[Dragonheart]

Keven, you pretty much nailed it. If you increase the dynamic load it is going to take longer for the surface of ALL the bullets to come up to curing temp. So you can take a guess as to whether the load is up to temp or use a thermometer that you can make yourself with a little help from Amazon or Ebay. Just cast a thermocouple lead into one of your bullets and you have your thermometer that will tell you when this bullet has reached the curing temp. Of course to be accurate the thermocouple bullet needs to be placed in a location in the oven that comes up to temp last. This way you can be assured all the bullets have reached curing temp. With this thermometer if you load varies it is not a problem. This is not my idea, this idea is not new, this idea is the basis of a thermometer, which if I believe came about in the colonial era.

[Morgan61]

I use the same PID I use in my lead melting pot. Swap out the thermocouple with one made for monitoring air temps.
I preheat the oven first. Then put in my boolits and when the oven temp recovers to about 380 degrees I start the timer. It only takes about 5-10 minutes or so for the temp to rise from 380 to 400 so I time it for 25 minutes

[Phlier]

For those of you interested in casting a boolit around a thermocouple, I've found a couple of products that work really well. Please note that the following are NOT affiliate links; I do NOT earn a commission on the sale of items purchased by clicking on these links (I hate it when people sneak in affiliate links on forums, but I digress...), they are products that I purchased and found to work well:

I got this thermocouple reader: Thermocouple Thermometer, RISEPRO 4 Channel K Type Digital Thermometer Thermocouple -200~1372°C/2501°F Sensor HT-9815

It's four channel, it's cheap, and you can set it to not turn off automatically. IMO, it's ok to go cheap on a thermocouple reader. All a thermocouple reader does is read the voltage of the thermocouple and convert it to read as a temperature. With an Arduino and 15 minutes, you can program your own extremely accurate reader. The real magic is in the thermocouple itself, so if you want extremely accurate readings, you want to invest the money into a good quality thermocouple.

There are other, cheaper thermocouple readers out there, but 25 bucks for four channels was/is a pretty good deal.

Here's the thermocouple that I cast a boolit around: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

This thermocouple is nice, as the fiberglass insulation around the wires is resilient enough to stand up to casting temperatures, and plenty strong enough to take the lower oven temperatures. The clip on it makes it very convenient for those of use that throw boolits in a big heap in an air fryer basket, as it allows you to accurately place the thermocouple in the heap and have it stay right where you want it.

This thermocouple is really accurate for a K type, too. The ice-in-water test showed 33F, and the boiling water test (I'm at 2,500 feet above sea level, so the lower temp is to be expected) showed 209F. Pretty darn accurate. Certainly good enough for powder coating purposes.

I got two of these thermocouples... one to cast inside a boolit, and the other to clip onto the outside of the air fryer basket to get an accurate oven temperature. You don't really need the second one, but it's nice to have so that you can watch the temperature of your oven easily.

You can go cheaper on the thermocouples if you'd like, as we don't really need extremely precise accuracy for what we're doing. Just make sure that you get a thermocouple that has good enough insulation to survive the temperatures it'll be used in. Even though K type thermocouples have a really large range of temperatures they can be used in, it's often the insulation used that limits that range, often times quite significantly. Most of the time, the listings will show the temperature ranges that the probe/wire can be used in, but sometimes the temp range isn't included. So take a look at the insulation... if it's a fiberglass type or braided metal, you're gonna be fine for using it in the oven. But if it's some cheap plastic, it's gonna melt. Use your best judgment. The "you get what you pay for" rule definitely applies to thermocouples. You want a good one, it's gonna cost you.

So the first time I used the probe cast into a boolit, it was a bit of an eye opener; sure enough, the boolits in the middle of the huge 20 pound heap weren't getting hot enough during my normal 25 minute bake. I had to extend my cook time to 35 minutes in order to keep the "center mass" boolits above 400F for ten minutes.

Big thanks to Dragonheart and the other guys that have provided the very useful help and suggestions in this thread.

Edit: And now today the thermocouple that I linked above is now showing out of stock, and only sold (at excessive prices) from third party sellers. It was 15 bucks on Amazon when I bought it a few days ago.

[slide]

Well done Philer! I think you will like it. I was lucky that my Son has a water testing lab. He has a tech come in and test the thermometers,scales, and other stuff used for measuring in the lab. Everything has to be certified. I ask him to check my three digital thermometers and luckily they were on the mark. If you don't mind I might pass your post onto Ausglock. He came up with the method. I have dubbed it the a.t.m. Ausglock's thermocouple method.

[Dragonheart]

Phlier, glad the thermocouple has worked for you. I am always happy to share information and thanks for posting your finds. I am not surprised that extra cooking time was needed. When I cooked some 6K+ 9mm in my PID converted 30" oven it took two 220v elements running full on for almost and hour for all the bullets to get to 400F. I use two digital thermometers the first of which I purchased for $3 in 2012 and it is still working, although I have had a couple of the thermocouples go bad, usually the wire leads from opening and closing the oven doors on them. I am amazed at the accuracy of these cheap chinese thermometers.

Actually the whole PC process is very simple and when there is a problem chances are it's the cure. With your 4 leads I can't see that ever happening top you.