Monitor Your Cooking Time

[Dragonheart]

I am making this post because as new people get into the world of Powder coating (PC) the same questions continue to be asked over and over again.
The most often asked question and the one most likely to cause under cured coating problems is: How do I establish the cure time for my bullets?

If you are using a toaster oven the simplest method is put a Taylor Oven Guide Thermometer on a shelf and monitor the air temperature inside the oven. I recommend the Taylor as these glass thermometers are inexpensive, accurate and react almost immediately to change.

However realize air temperature and the temperature of the bullets substrate is not the same. Meaning the curing time powder manufactures specify is based on when the surface of the coated object (in our case bullets) reaches the desired temperature, usually 400 F. degrees. So you air temperature may be reading 400, but that does not mean the bullets have reached 400 degrees.

Once again the simplest way is to add some time and that is what most do, but also realize it is just a guess. If you guess right and the bullets come out completely cured then as long as you the same thing (time, temperature and quantity of bullets) every time you should have success.

But what happens if you want to cook a larger quantity or you would really like to know and control your process and not keep guessing? Simply construct a thermocouple to measure the internal temperature of the bullet.

This is simple to do and not expensive. Anyone capable of handling molten metal should have no problem doing this. First you need to purchase a digital thermometer with a bare probe. I have used the one in the photo for years; I originally purchased to check the temp of my casting furnace. The thermometer still works, but the thermocouples wires do go bad, fortunately they are inexpensive, so I always have spares.

The thermometer in the first photo is a TM902C Type-K. It only reads in Centigrade, but converting is not a problem as 400 F. = 204 C. These thermometers are available from Amazon and EBay starting for under $5 including one bare type K thermocouple. A better choice might be a Proster Digital Thermocouple Thermometer with Two K-Type available from Amazon for $26. This allows for two thermocouples to be monitored at the same time.

To make a thermocouple cast the end of the bare thermocouple wire into a bullet, see photo #3. Having an extra pair of hands to help makes this much easier. Getting the mold hot so you have enough time to insert the wire and alloy is the key to success. Needless to say cast bullet with an open sprue cutter.

Once you have a bullet thermocouple (photo 2), or several, you can now monitor the temperature in several places if in your oven as there can be hot & cold spots, but convection helps. When your bullet thermocouples are up to temp then surrounding bullets should be up to temp also, but multiple trays can have different temps, so monitoring in two or more places can be an asset for large numbers of bullets. The bullet thermocouple with a Taylor Thermometer allows you monitor your process both air temperature and substrate temperature and stop guessing.

[44MAG#1]

As most know on here, I am one who marches to the beat of a different drummer. That is because there are more than one drummer.
I checked my oven when I first got it with an inside temp device. I se the oven to the temperature that the inside temp device indicated I should. I then powder coat, shove the bullets in and set the timer for 30 to 35 minutes. When there is about 5 minutes left I open the door and stir the bullets to keep them from sticking together, (a few still do), shut the door and finish baking. This works for me. I have put the bullet in a small container of Titegroup powder and let them set for a few days, sprayed them with Hornady case lube, smeared White Label lube on them, even their tumble lube and smashed them with a big hammer. After these tests I see no problem in my method. The bullets shoot as well as I can shoot, barrel stays fairly clean shot low powered on to high powder loads. My powder coating job works. So to me my method is okay for me. It most certainly wont work for everyone as no one method will.
My belief is if what ever method is working for that individual then that method is okay. Not saying it is okay for EVERYONE else.
I use Eastwood powder paint.

[slide]

Another way of attaching the thermocouple to the bullet is with high heat aluminum tape. This way you can remove bullets and put on another. If I am baking 223 I like the t-bullet to be 223 and so on. If you heat your molds remove the bullet and stick the thermocouple into one of the cavities. Attach a probe and you can monitor your casting pot without a pid. I have been using the thermocouple method since January of 2016. That is when I came up with the idea. As simple and as cheap as it is very few people use it. If what you are doing works stay with it. I try and do every thing as close to right as I can. Conditor22 is right on. Why risk powder ruining your powdercoat because it is not baked properly. Honestly, I wish I had never posted about the idea. I acutally had one guy try and steal the idea and take credit for it and others raising cain that it was somebody elses idea. This is a big part of why I don't post much anymore.

[charlie b]

Thermocouples have been used for decades in bullet casting. Yes, in bullets too. We used to do that when heat treating to make sure the bullet interior was up to temp. That was in the early 80's. And, it wasn't our idea. I think we got the idea from an issue of Precision Shooting magazine.

[Dragonheart]

Thermocouples have been used for decades in bullet casting. Yes, in bullets too. We used to do that when heat treating to make sure the bullet interior was up to temp. That was in the early 80's. And, it wasn't our idea. I think we got the idea from an issue of Precision Shooting magazine.

Charlie, you are right on, because the thermocouple is about 200 years old. The only difference is where and how it is used.

[Txcowboy52]

That's a great idea ! Good way to have a better idea of actual bullet temperature.

[slide]

Try it! It doesn't cost much. You can do the same thing with a muti meter if it checks temp. This started out as a way to cure hi-tek coating. Everytime I baked a batch of bullets I would get flaking and color wipe off. When I started using the t-couple those problems went away. It works just as well with powdercoat. I am not saying this is the be all end all way. It has worked well for me and some others. Everyone has a different way of doing it. You can use the setup for other things beside just baking bullets so you get your moneys worth if you buy one.

[charlie b]

Charlie, you are right on, because the thermocouple is about 200 years old. The only difference is where and how it is used.

That's the point. I saw people use it in bullets back in the 80's. Not a new idea.

[slide]

I never said it was a new idea,just an idea. Yeah, thermocouples have been around a long time. I also didn't say I invented thermocouples. I had a problem and used a tool to solve it.

[Dragonheart]

Try it! It doesn't cost much. You can do the same thing with a muti meter if it checks temp. This started out as a way to cure hi-tek coating. Everytime I baked a batch of bullets I would get flaking and color wipe off. When I started using the t-couple those problems went away. It works just as well with powdercoat. I am not saying this is the be all end all way. It has worked well for me and some others. Everyone has a different way of doing it. You can use the setup for other things beside just baking bullets so you get your moneys worth if you buy one.

The thermocouple is just another tool in the box like a thermometer and there are still a lot that refuse to use a thermometer and that's their choice. But actually, I think the thermocouple is the "be all end all" simply because everyone that says I just pop em' in an oven, set the dial and take em' out and it works great for me is just guessing.

Yes, this method may work for you and it worked for me, until I started increasing the load and had some undercured bullets because I guessed wrong. The guess method doesn't give a new person trying out PC for the first time any guidelines.

Ovens vary in size, power insulation, etc. The load is a moving target, do you cook 50 bullets or 5000? The other element time is also a moving target because it changes depending on the oven and the load. With a simple thermocouple it makes no difference because it tells you when to start timing. Now I can cook 50 or 5000 bullets, and I do. The thermocouple relieves me of the worry about a load whether it be 50 or 5000 coming out undercured. It doesn't make any difference to me who came up with the idea, but I am sure glad they did. Like a using a thermometer it is just a better idea.

[farmerjim]

I did it the simple way. I painted a stripe of 400 deg tempilaq on 3 of my boolits that were spread around on a full tray. At 6 minutes I get the color change so I just bake for 10 more minutes. I found that all my different boolits are within 1 minute of the 6 that my 125 gr 9mm ones change.

[slide]

I used the t couple for quite a while and kept it to myself. After thinking it over I decided to post on this forum hopefully to help. It is the only sure way I can tell where I am in the curing stage. Other people have all kinds of ways which is great,carry on. I have fought a running battle with people who try and take credit for the idea or other crap is thrown at me. I would have been better off to have never posted it. Let me put it this way. If you went to a shooting competition and you won an award. When they called your name someone else took that award in your place. What would you do? I don't expect parades and flowers.It is not that big of a deal. I have had jobs where a lot of the credit stealing went on. It is a sore spot with me I guess. I will try and not be so thin skinned in the future. We are supposed to be a brotherhood of like minded people who want to help each other. If we don't I can promise you that reloading will die. That is my rant for the day. If anybody has any questions you can contact me or Dragonheart.

[Dragonheart]

I did it the simple way. I painted a stripe of 400 deg tempilaq on 3 of my boolits that were spread around on a full tray. At 6 minutes I get the color change so I just bake for 10 more minutes. I found that all my different boolits are within 1 minute of the 6 that my 125 gr 9mm ones change.

I looked into Tempilaq and was told it had a 1 year shelf life and I never went any further, because I go in spurts where I cast. I cast and coat tens of thousands of bullets and then I may go a long time before another spurt, but it sounds like a really good idea. I already had the digital thermostat and several bare K probes I purchased in 2012, so no additional outlay wasn't required.

[fredj338]

I think too many make things too diff. Verify the oven temp is 400 deg. Coat & bake for 15m total time, done. It has been working for me.

[kevin c]

This might be overkill on my part, but I figure that the lead around the K probe should be close to the weight of the bullets being coated. Additionally, for HiTek, at least, with its heat reflective properties that vary depending on the pigment (reflective metal particles in some), temperature rise in the same oven air temp can vary. As a result, I use a cast, sprue cut bullet, coated with the same color and drilled out at the base, for the test bake for each color. A toothpick wedges the probe in place.

[slide]

That is good thinking kevin c. I like your toothpick idea. My tape sure is ugly.

[oconeedan]

Thank you for posting this! I was thinking the thermometers were much more expensive. In fact, these are comparable with the Taylor Oven Guide thermometer you mentioned.
I found one on Amazon that looks good, and will display F or C.
Search for "PEAKMETER PM6501"
Dan

[slide]

oconeedan, that should do the trick.

[Dragonheart]

I think too many make things too diff. Verify the oven temp is 400 deg. Coat & bake for 15m total time, done. It has been working for me.

Exactly my point, it works for you and that's great and you should continue with what works for you. But new people first starting out don't know what kind of oven you have, is the oven working properly, what was the mass placed in the oven and did the mass actually come up to 400 for 10 minutes.

I have been PC bullets since 2012 and I can't look at a beautiful coated bullet and tell if it is properly cured. The smash test doesn't tell you if the PC has reached full strength it only shows a bond and the elasticity of the coating. The scrape test can tell if the coating is soft and the pencil test can tell you how hard the coating is. The Thermocouple can tell you the coating reached temperature and a timer can tell you for how long it stayed at that temp, without guessing.

[Dragonheart]

Thank you for posting this! I was thinking the thermometers were much more expensive. In fact, these are comparable with the Taylor Oven Guide thermometer you mentioned.
I found one on Amazon that looks good, and will display F or C.
Search for "PEAKMETER PM6501"
Dan

You are welcome.

There are a number of meters available that are inexpensive, some with multiple K probes. I mentioned the one I purchased back in 2012 because it was so cheap even now ($5 on Ebay) and it still works. I actually use more than one for my large oven, plus it is a double check on the temperature. Even with the thermocouple I still use my Oven Guide also.