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Thread: How do you check oven temp?

  1. #1
    Boolit Buddy
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    How do you check oven temp?

    So I had been trying to watch the temp in my toaster oven when doing powdercoating. I laid my RCBS lead thermometer on the top rack and set bullets on the bottom. Kept the temp at 425 for 15 minutes and thought all was well. Took it out and 1 bullet is slumped over. Uh-oh. Looked at the others and about a third have kind of a thick area at the base where it appears that lead was starting to get soft and sag. So I can think of 2 possibilities. Either thermometer is off, or I have some significantly different temperatures in my toaster oven. Oven is not a convection. So I was wondering what thermometers you all use. Thought maybe that the lead thermometer measures based on contact not air temp.

  2. #2
    Boolit Grand Master
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    https://www.engineeringtoolbox.com/m...als-d_860.html
    Depending on your alloy, the oven is too hot
    Regards
    John

  3. #3
    Boolit Master
    Chad5005's Avatar
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    a regular oven thermometer

  4. #4
    Boolit Master
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    I also use the common inexpensive over thermometer. My oven is convection, I pre-heat, then remove the thermometer, slide in my two trays of bullets, allow 5 minutes to come back up to heat and then run my timed cycle. If I have more runs to make, the trays are already set with powdered bulltets and I consider the oven to be pre-heated and simply swap trays - bless those silicone cooking gloves. LOL

    prs

  5. #5
    Boolit Buddy
    EMR's Avatar
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    I used a $5 over thermometer before I switched to a PID for the oven. Both are accurate. One is much less work

  6. #6
    Boolit Master slide's Avatar
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    You could use the A.t.M. (Ausglocks thermocouple method). Cost you around twenty bucks. Order a digital thermometer with a thermocouple off of amazon,or get a multi tester at wal mart that comes with a thermocouple. Drill a hole is a coated bullet and secure the thermocouple in the hole. I use high heat aluminum tape. Some will tap the base of the bullet until it closes on the thermocouple. Put the themocouple in with your bullets when cooking. This way you know when your bullets reach the right temp and start a timer. Most of my powders are 10 mins. at 400F. When my bullets reach 400F I start a countdown timer from 10 mins. No offense to anybody else but with other thermometers you are measuring the air temp of the oven and not the temp of the bullets. I have been using this method for four years now.
    Boolits !!!!! Does that mean what I think it do? It do!

  7. #7
    Boolit Master
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    Quote Originally Posted by Jevyod View Post
    So I had been trying to watch the temp in my toaster oven when doing powdercoating. I laid my RCBS lead thermometer on the top rack and set bullets on the bottom. Kept the temp at 425 for 15 minutes and thought all was well. Took it out and 1 bullet is slumped over. Uh-oh. Looked at the others and about a third have kind of a thick area at the base where it appears that lead was starting to get soft and sag. So I can think of 2 possibilities. Either thermometer is off, or I have some significantly different temperatures in my toaster oven. Oven is not a convection. So I was wondering what thermometers you all use. Thought maybe that the lead thermometer measures based on contact not air temp.
    I now use the ATM method (slide ) mentioned, also use convection oven. Before I got the convection oven, I had regular toaster oven and had to watch it like a hawk. They are a lot of cool and hot spots all around inside.
    Never had boolits melt though, or slump, can see that happen if you have your thermometer in a cool spot.

  8. #8
    Boolit Master


    Kraschenbirn's Avatar
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    My technique is pretty much the same as PRS (Post #4) using a bimetallic oven thermometer (which reads within 5 deg. of my Taylor digital meat thermometer). PC'd 350+ 500 grain RNFPs for .45-70s this afternoon without a single cull.

    Bill
    "I'm not often right but I've never been wrong."

    Jimmy Buffett
    "Scarlet Begonias"

  9. #9
    Boolit Master
    Dragonheart's Avatar
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    Just buy a glass Taylor Oven Guide Thermometer (about $12 on Amazon) and place it where you can see it through the glass in the oven door. It is accurate, fast reading and easy to read. This will accurately give you the air temperature of the oven, but that does not tell you the surface temperature of the bullets. If you are like most here and going to only cook a couple of hundred bullets at a time just add some time to allow for the bullet surface temperature to come up to 400. In most cases an extra 10-15 minutes plus the suggested cure time for the powder which can vary but most are 12 minutes.

    If you are cooking hundreds or thousands of bullets on multiple trays then a thermocouple or two takes out most of the guesswork.

    A PID works great for maintaining a constant air temperature in the oven at the probe, but that is all it does. A PID will not tell you what the substrate temperature of the bullets is or how long they need to cook.

  10. #10
    Boolit Buddy pacomdiver's Avatar
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    i had 2 toaster ovens that held temp good, and 1 that wouldnt hold constant temp, but could only do small batches on the small trays, last year my wife wanted a new stove, so the old one got moved out into my shop, havent used my toasters since and i can cook 3 big trays at once

  11. #11
    Boolit Master
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    Quote Originally Posted by pacomdiver View Post
    i had 2 toaster ovens that held temp good, and 1 that wouldnt hold constant temp, but could only do small batches on the small trays, last year my wife wanted a new stove, so the old one got moved out into my shop, havent used my toasters since and i can cook 3 big trays at once
    A big oven is where one or more thermocouples are of great benefit. My 30" oven does a great job and I do thousands of bullets in a single cook, but you would be surprised at how long 5K bullets takes to come up to temp after the PID reaches 400 degrees. The Chinese K-type digital thermometers are about $7 and a package of several K-type thermocouples are also cheap. Just cast the end of a thermonuclear lead into a bullet and place the bullet in the oven at the coldest spot. Finding the cold spots is also easy just use a couple of thermocouples. Some of these inexpensive digital thermometers will handle 4 or more leads at the same time.

  12. #12
    Boolit Master
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    I also use a K-type digital thermometer, I have used the same one for a couple of years, so they seem to hold up well.

  13. #13
    Boolit Master
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    I am still using the TM-902C Digital LCD Thermometer I got off Ebay for $3 back in 2012. I did have to replace the K probe I used for the casting furnace. I have since bought a couple more as well as several thermocouples so I can monitor multiple ovens or multiple places in an oven.

  14. #14
    Boolit Grand Master

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    I use a Taylor oven thermometer from WalMart, about $5.
    Hell, I was there!

  15. #15
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    Walter Laich's Avatar
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    built a PID for PC oven. holds within 1
    NRA Life
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    RVN War Games, 2nd Place

  16. #16
    Boolit Master
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    Quote Originally Posted by swheeler View Post
    I use a Taylor oven thermometer from WalMart, about $5.
    If is the glass Taylor Oven guide, they do an excellent job, it it is a spring model they are typically too slow to read and prone to inaccuracy.

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