Number of PC coats to prevent leading

[Dragonheart]

Flintfire you are right, powder manufactures curing specifications stipulate the temperature of an object's surface, in our case the bullets surface.

The thermocouple cast into a bullet is just a thermometer that is reading the temperature inside the bullet, but once the center of the bullet thermometer reaches 400 you know the bullet surface has already reached that temp. Since all ovens, even convection, have hot & cold spots placing the bullet thermometer in the coldest spot of the oven pretty well assures when it reaches 400 all the other bullets in the oven have also reached 400. So timing from that point assures we have met the manufacturer's specifications. If still in doubt add more time.

The whole point to my mentioning making your own bullet thermometer is it is an easy way to monitor the curing process regardless of any changes made in the future.

[FLINTNFIRE]

Dragonheart , I see what you are saying , it was you that pointed me at the thermometer to get , I have a pid , but I do not have a very big convection oven , I watch the thermometer while doing other stuff and then I adjust time , have not actually used pid on my pot as I amd running the newer promelt2 doing a run it and see how it holds up , have so many coffee cans full of different 9mm bullets all coated am now working on 32-20 and 40 bullets , did a bunch of 45acp and then went back through all the coffee cans of cast and unlubed , removed all oxidized and coated the rest , at the present I am melting all the lubed and casting and coating , I would like to say , do take the time all to cook at temp. and for the time needed , and keep us informed of likes , dislikes , and what you find in your time and with your methods , to all who are coating may this year bring continued success and to all those thinking of starting jump in and do it , I loaded a bunch of lubed while waiting to finish my new casting coating area and now only wish I had just started coating sooner ..

[Bill P.]

Yesterday I went and got a multi meter with thermocouple , then I drilled a 1/8" hole in the base a .40 bullet off-set so to be as close to the actual surface as possible. Then secured thermocouple in with a small piece of high temp aluminum tape. the thermocouple wire is plenty small enough to still close the oven door and is insulated quite well with some kind of high temp material. I think this is the way I will go from now on it is so easy that one can't mess it up. You get actual real time bullet temp so you can set your timer when bullet reaches required temp. In my opinion this is the best way for a newbie powder coater like me. Everthing cost like 30 bucks that's a cheap way to avoid the headache I was having. I would have never come across this method if not for the people here on castboolits!

[slide]

Glad you like it Bill P. The new name for the method is a.t.m. (ausglocks' thermocouple method) He came up with the idea a couple of years ago. He has a different name for it but, I won't mention that in a public forum. No more guessing,now you know!

[Dragonheart]

Bill P, I agree completely, if you can cast bullets it is so easy to make a thermometer just for PC bullets. If fact the thermocouples are so reasonable you can make up several and take readings in multiple areas of the oven or have a spare.

I have posted this information several times, but for those that want to give it a try this is what I started with and still use, from Amazon 5 (five) thermocouples: uxcell 5 Pcs K Type Temperature Thermocouple Sensor Wire -50C to +200C 2M $7.39.

For the thermometer also off Amazon: LCD K-Type Digital Thermometer TM-902C w Thermocouple Wire $11.32. amazon Prime delivers these next day but you can find this same thermometer for less than $7 if you want to wait for delivery or off Ebay. Obviously there are more expensive thermometers and some with multiple thermocouples, but this El Chepo thermometer I found to very accurate, tested against my mercury serviceman's oven thermometer.

If you get a k type thermocouple with a metal probe it doubles as an accurate thermometer for your casting furnace, tested against my NOE thermometer

I found the easiest method to make the bullet thermometer was to enlist a helper to pour or hold the lead in a bullet cavity on a heated mold then pour in the hot lead to fill the cavity.

[slide]

Someone might try this. We did some experminting with the a.t.m. Bear in mind this was with hi-tek. We took a uncoated bullet and a hi-tek coated bullet,placed them in the oven with thermocouples. The hi-tek bullet absorbed heat slower than the plain bullet. Enough that you would need to adjust your baking time. It could make a difference,I'm not really sure with powder coat?

[Dragonheart]

[QUOTE=slide;4804125]Someone might try this. We did some experminting with the a.t.m. Bear in mind this was with hi-tek. We took a uncoated bullet and a hi-tek coated bullet,placed them in the oven with thermocouples. The hi-tek bullet absorbed heat slower than the plain bullet. Enough that you would need to adjust your baking time. It could make a difference,I'm not really sure with powder coat?[/QUOTE

Interesting, I know rate of absorption will vary due to the material like copper would be about three times faster than lead. Additives like tin and antimony will also cause a different transfer rate. I would imagine the Hi-tek coating acted as an insulator. I would suspect PC would also act as an insulator, but the normal thermal transfer rate for a single bullet would likely be measured in seconds. I wouldn't spend a lot of time worrying about if the thermocouple inside the bullet is reading 400F. and the bullet is in the coldest part of the oven. When I have taken multiple measurements uneven oven heating, even with convection, makes much more of a difference. But this would be more of a problem for those like me who cook multiple racks of bullets at a time.

I personally give my bullets at least 15 minutes at 400F after the coldest spot comes up to temp. My discussing curing with the techs at Prismatic Powder as well as with a polymer physicist have told me adding a little extra time is not going to hurt, but not so much that the color starts to alter.

[GREENCOUNTYPETE]

my 9 and 40 in my convection oven only need about 10 minutes if I don't get them out soon after 10 they start to darken in color , it is possible my oven is hotter than the setting.

convection makes things cook faster

the oven starts preheated

single coat of Harbor freight red applied with air soft bbs and #5 container placed on parchment with a nitril gloves fingers dipped in powder grabbed bullets by the nose

124gr tc and 170gr tc lee molds

the 124 drops big like .359 to .360 works for me as I run them in 38spl also
size to .356 and .401 post coating

I would think sizing might be the issue

you could bake a batch 12 , 14, 16 , 18 minutes see when your bullets darken in color and go back to the last time that didn't darken

I bake only one tray at a time generally full

[Dragonheart]

my 9 and 40 in my convection oven only need about 10 minutes if I don't get them out soon after 10 they start to darken in color , it is possible my oven is hotter than the setting.

convection makes things cook faster

the oven starts preheated

single coat of Harbor freight red applied with air soft bbs and #5 container placed on parchment with a nitril gloves fingers dipped in powder grabbed bullets by the nose

124gr tc and 170gr tc lee molds

the 124 drops big like .359 to .360 works for me as I run them in 38spl also
size to .356 and .401 post coating

I would think sizing might be the issue

you could bake a batch 12 , 14, 16 , 18 minutes see when your bullets darken in color and go back to the last time that didn't darken

I bake only one tray at a time generally full

I would say your oven is too hot. Do not rely on the oven dial to be accurate. you need a thermometer set inside the door so you can monitor the temp.
All my ovens are convection. The fan just circulates the air for more even and faster heating. The only time I have run into darkening was on two occasions. One I forgot to set the timer and my bullets cooked for 24 hours. the second was when a tray was too close to the upper element, my remedy was to load only 4 trays and not 5.
I would also suggest casting a thermocouple lead into a bullet (see above) so you have a thermometer that will mimic the heat transfer of the bullets. Placing it in several places in your oven can tell you where the cold spots are, especially if you load up an oven as I do. Having it in the coldest spot in the oven and starting the time when it comes up to temp should give you a good cure.

[Dapaki]

I was the weekend, overnight floor supervisor at LifeFitness for about 18 months (we made exercise machines for fitness centers worldwide) and I had a 1000' baking tunnel on our powder coating line and while I was not an operator, I had to audit QA on the PC line (not patting my own back here, just setting up the point to be made).

We tested what was called the "cure schedule" in which under curing or over curing was closely monitored. Since the "cure" was really waiting until the cross-linking was completed at an appropriate temperature, we had the ability to cure the PC on 18ga tube as easily as 1/4" plate for the floor supports. Each powder had some special requirements but overall, if the surface reaches X degrees for Y time, you have a good cure.

We exclusively used IR guns to temp the line, PID's were used to measure the heat in the tunnel (natural gas, indirect) but our only concern was the temp of the surface and the time it was at a prescribed temperature. And while I like the thermostats and thermocouple ideas, I think you are chasing your tails since we never had a part leave the tunnel that was 400 degrees and we had no cooling/rest area, they came out on hangers and were removed as they were needed for staging and assembly and could be handled with gloves within minutes of exiting the oven.

My humble advice is to use a cheap IR gun to detect the surface temperature, just use a piece of cardboard to shield the booilts from the element for a second while taking your sample.

Again, these are just my experiences from an industrial powder coating line, your boolits may vary.

[Dragonheart]

Dapaki, I understand where you are coming from, as I visited professional coating operations when I first got into to this back in 2012. I also questioned technicians as well as polymer physicists. I wanted to learn as much about the process so I could determine what worked best for my interest; not that I am suggesting anyone do this, but that is just me. Out of all the true professionals in the polymer field I didn't find a one that knew anything about powder coating bullets. The physicist found coating bullets extremely interesting and provided me with a lot of very useful information, but it was all conjecture. Over the last 8 years I have taken what I learned from the pros and the conjecture based on what the polymer should be capable of and proven to myself through experimentation what PC can do. This was necessary because even with what I learned there was not a bike frame, tool, auto part or exercise equipment that was powder coated then fired down a tube at 3500 feet per second. The difference being is if the commercial parts had a pretty finish it didn't make that much of a difference. If my bullets have a pretty finish and the bullet is not properly cured I have a mess to clean up and a bullet that didn't perform properly.

Taking a reading with an IR in a toaster oven is very different from what I saw in commercial operations. Opening a door on a toaster oven and you have a major heat loss, with a slow recovery. If you are only cooking a couple of hundred bullets you don't need an IR. Just monitor the air temp. Once it is stable add an extra 10 minutes and likely it will be just fine. However, when those like myself get to the point of cooking thousands of bullets packed tightly together on multiple racks with a convection oven, the substrate temperature of the individual bullets will vary considerably until they stabilize. Trust me when I say an IF for what I am doing is not practical, I tried it years ago. If you are going for production and cooking a lot of bullets the thermocouple works better than anything I have tried. Multiple thermocouples work even better and they are so easy to make and very inexpensive. Try it and I think you will be pleased.

[Dapaki]

Dapaki, I understand where you are coming from, as I visited professional coating operations when I first got into to this back in 2012. I also questioned technicians as well as polymer physicists. I wanted to learn as much about the process so I could determine what worked best for my interest; not that I am suggesting anyone do this, but that is just me. Out of all the true professionals in the polymer field I didn't find a one that knew anything about powder coating bullets. The physicist found coating bullets extremely interesting and provided me with a lot of very useful information, but it was all conjecture. Over the last 8 years I have taken what I learned from the pros and the conjecture based on what the polymer should be capable of and proven to myself through experimentation what PC can do. This was necessary because even with what I learned there was not a bike frame, tool, auto part or exercise equipment that was powder coated then fired down a tube at 3500 feet per second. The difference being is if the commercial parts had a pretty finish it didn't make that much of a difference. If my bullets have a pretty finish and the bullet is not properly cured I have a mess to clean up and a bullet that didn't perform properly.

Taking a reading with an IR in a toaster oven is very different from what I saw in commercial operations. Opening a door on a toaster oven and you have a major heat loss, with a slow recovery. If you are only cooking a couple of hundred bullets you don't need an IR. Just monitor the air temp. Once it is stable add an extra 10 minutes and likely it will be just fine. However, when those like myself get to the point of cooking thousands of bullets packed tightly together on multiple racks with a convection oven, the substrate temperature of the individual bullets will vary considerably until they stabilize. Trust me when I say an IF for what I am doing is not practical, I tried it years ago. If you are going for production and cooking a lot of bullets the thermocouple works better than anything I have tried. Multiple thermocouples work even better and they are so easy to make and very inexpensive. Try it and I think you will be pleased.

No need to convince me DH, I have PID's all over the house, brewing station, lagerator, lead pot, outdoor wood boiler and SWMBO's sous vide pot.

I PC about 100 boolits each bake, nothing like your production. I cant miss with 400 degrees and 20 minutes, no matter who's PC it is.

[Dragonheart]

No need to convince me DH, I have PID's all over the house, brewing station, lagerator, lead pot, outdoor wood boiler and SWMBO's sous vide pot.

I PC about 100 boolits each bake, nothing like your production. I cant miss with 400 degrees and 20 minutes, no matter who's PC it is.

A PID for a homemade sous vide turned out the best whole brisket I have ever made, but that is a different story.

[Dapaki]

Agreed! SWMBO showed me a $500.00 sous vide pot a few years back telling me it will make the best pork I ever had! Never heard of the dang thing so I YouTubed a DYI version using a crockpot. Auber PID (first and last one ever), thermocouple, a box of crockpot bags and a little programming... Best butt I aver had! (There is a valuable joke somewhere in there) She is now on to pressure pots.

[Dragonheart]

A PID controlled crockpot works great for things that will fit in it. But for a 14 pound brisket I used an insulated drink box, a water heater element controlled by an Inkbird PID and a small water pump connected to a length of PEX pipe for circulation.

[Dapaki]

A PID controlled crockpot works great for things that will fit in it. But for a 14 pound brisket I used an insulated drink box, a water heater element controlled by an Inkbird PID and a small water pump connected to a length of PEX pipe for circulation.

WOW!!! Ahhhh... Texas!