Author Topic: CERAKOTE Cure Oven  (Read 6794 times)

Offline J Mack

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CERAKOTE Cure Oven
« on: October 30, 2010, 11:36:38 AM »
I have a few naked rifles now and a few more on the way so I'm looking making a cure oven that I can cure a barreled action in.
I found this on the internets and thought I would pass it along.

Plans: http://tenring.com/oven.htm

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Offline IdahoPreps

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Re: CERAKOTE Cure Oven
« Reply #1 on: October 30, 2010, 11:50:51 AM »
I've seen the same type of setup using an old locker (5' tall or so) and the element from a toaster oven.  The one you posted up looks a lot more "clean" though.

Offline Jeff

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Re: CERAKOTE Cure Oven
« Reply #2 on: October 30, 2010, 12:54:31 PM »
We just built one similar to that here in the shop.  The heating elements will probably be added tomorrow.
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Offline J Mack

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Re: CERAKOTE Cure Oven
« Reply #3 on: October 30, 2010, 01:26:18 PM »
We just built one similar to that here in the shop.  The heating elements will probably be added tomorrow.

Please post pictures if you get a chance.
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Offline meinidaho

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Re: CERAKOTE Cure Oven
« Reply #4 on: October 30, 2010, 09:08:49 PM »
We just built one similar to that here in the shop.  The heating elements will probably be added tomorrow.

So does that mean you can apply color to a stainless steel barrel?

Offline Jeff

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Re: CERAKOTE Cure Oven
« Reply #5 on: October 30, 2010, 09:20:04 PM »
Yes it does. Cerakote is like paint but the coating is very thin. I have black and Magpul FDE colors in stock right now.

I also got some Micro Slick to use on bolts/carriers/etc. It doesn't require heat to cure.

http://www.nicindustries.com/dry_film_lubricants.php
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Offline berg

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Re: CERAKOTE Cure Oven
« Reply #6 on: October 31, 2010, 10:05:13 AM »
So does that mean you can apply color to a stainless steel barrel?

This rifle has a stainless steel barrel.  The rifle and action were painted by George Vais with air cure CERAKOTE last year, it is still wearing well.  If you have a custom rifle that has not been stress relieved you might want to read up some on finishes before you bake it.  (the silencers are also painted with CERAKOTE )
« Last Edit: October 31, 2010, 10:14:17 AM by berg »
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Offline berg

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Re: CERAKOTE Cure Oven
« Reply #7 on: October 31, 2010, 10:25:04 AM »
"A government big enough to give you everything you want, is strong enough to take everything you have".  

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Offline J Mack

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Re: CERAKOTE Cure Oven
« Reply #8 on: October 31, 2010, 11:18:14 AM »
If you have a custom rifle that has not been stress relieved you might want to read up some on finishes before you bake it.  


Thanks Berg,

All custom rifle barrels that I'm aware of have been stress relieved at least twice, once at the mill and once at the barrel maker. Button rifling (Rifling by displacement) and hammer forging (hamming the exterior barrel around a mandrel) introduce more stress than cut rifling (rifling by removing material) to the barrel but are still stress relieved at higher temperatures than we would cure the paint.


More info on stress relief of 4130 and stainless steel.

Stress relief is a type of heat treatment used to reduce or remove internal stress induced into metal components from various manufacturing methods (bending, shearing, forging, sawing, machining, grinding, milling, turning, welding, heating, cooling). As a general rule, the larger or more complex the part, the greater the amount of internal stress present.

In heat treating, rapid cooling/quenching alone or in combination with pre-existing internal stresses can result in unwanted distortion, brittle fracture and stress corrosion cracking if near welds in certain grades of metal.



Stress-relief operations are typically done by subjecting the parts to a temperature approximately 40-75C (105-165F) below the A1 transformation temperature about 727C (1340F) for steel. Stress relief is typically performed for carbon steel at approximately 500-650C (930-1200F). The elimination of stress is not instantaneous (that is, the process is a function of both temperature and time). To achieve the maximum benefit, some time at temperature (typically one hour per 25 mm of cross-sectional area once the part has reached temperature) is required. This removes more than 90% of the internal stresses. Stress relief on alloy steels is often done at (slightly) higher temperatures. After removal from the furnace or oven, the parts are air cooled in still air. Rapid cooling will only serve to reintroduce stress and is the most common mistake made in stress-relief operations.

For tool steels, the process is similar. It is common to perform a stress-relief operation in the temperature range of 500-550C (9251025F) allowing the parts to slowly cool to room temperature before subsequent operations.

For stainless steels, the situation is more complex. Stress relief is done in the range of 290-425C (550-800C), which is below the sensitization range. The operation is typically broken down into several cases.

1. When stainless steel sheet and bar experience a reduction in area in the neighborhood of 30%, there is a peak in internal stress coupled with an increase in both tensile and yield strength. Stress relief will help reduce movement in subsequent machining operations. Since it is performed at temperatures below 425C (800F), carbide precipitation and sensitization to intergranular attack (IGA) are not a problem even in the higher carbon grades.

2. After machining, stress relief at 425-595C (800-1100F) is normally adequate to reduce stress and minimize distortion that would otherwise exceed dimensional tolerances after machining. If weldments are involved, only the low-carbon "L" grades or the stabilized 321 and 347 grades above 425C (800F) as the higher carbon grades are sensitized to IGA when heated above about 425C (800F).



Link:http://www.industrialheating.com/
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Offline berg

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Re: CERAKOTE Cure Oven
« Reply #9 on: October 31, 2010, 11:36:27 AM »

Thanks Berg,

All custom rifle barrels that I'm aware of have been stress relieved at least twice, once at the mill and once at the barrel maker. Button rifling (Rifling by displacement) and hammer forging (hamming the exterior barrel around a mandrel) introduce more stress than cut rifling (rifling by removing material) to the barrel but are still stress relieved at higher temperatures than we would cure the paint.


More info on stress relief of 4130 and stainless steel.

Stress relief is a type of heat treatment used to reduce or remove internal stress induced into metal components from various manufacturing methods (bending, shearing, forging, sawing, machining, grinding, milling, turning, welding, heating, cooling). As a general rule, the larger or more complex the part, the greater the amount of internal stress present.

In heat treating, rapid cooling/quenching alone or in combination with pre-existing internal stresses can result in unwanted distortion, brittle fracture and stress corrosion cracking if near welds in certain grades of metal.



Stress-relief operations are typically done by subjecting the parts to a temperature approximately 40-75C (105-165F) below the A1 transformation temperature about 727C (1340F) for steel. Stress relief is typically performed for carbon steel at approximately 500-650C (930-1200F). The elimination of stress is not instantaneous (that is, the process is a function of both temperature and time). To achieve the maximum benefit, some time at temperature (typically one hour per 25 mm of cross-sectional area once the part has reached temperature) is required. This removes more than 90% of the internal stresses. Stress relief on alloy steels is often done at (slightly) higher temperatures. After removal from the furnace or oven, the parts are air cooled in still air. Rapid cooling will only serve to reintroduce stress and is the most common mistake made in stress-relief operations.

For tool steels, the process is similar. It is common to perform a stress-relief operation in the temperature range of 500-550C (9251025F) allowing the parts to slowly cool to room temperature before subsequent operations.

For stainless steels, the situation is more complex. Stress relief is done in the range of 290-425C (550-800C), which is below the sensitization range. The operation is typically broken down into several cases.

1. When stainless steel sheet and bar experience a reduction in area in the neighborhood of 30%, there is a peak in internal stress coupled with an increase in both tensile and yield strength. Stress relief will help reduce movement in subsequent machining operations. Since it is performed at temperatures below 425C (800F), carbide precipitation and sensitization to intergranular attack (IGA) are not a problem even in the higher carbon grades.

2. After machining, stress relief at 425-595C (800-1100F) is normally adequate to reduce stress and minimize distortion that would otherwise exceed dimensional tolerances after machining. If weldments are involved, only the low-carbon "L" grades or the stabilized 321 and 347 grades above 425C (800F) as the higher carbon grades are sensitized to IGA when heated above about 425C (800F).



Link:http://www.industrialheating.com/

Most rifle actions have not been stress relieved from the factory,  (I know that some rifle builders do stress relive the action before machining)  if you true an action that has not been relieved, then barrel the action, then bake a finish on, it is "possible" that the action will "move" as the stress is relieved.  If you just spent a bunch of time truing the action face and lugs that might not be a good thing.
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Offline J Mack

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Re: CERAKOTE Cure Oven
« Reply #10 on: October 31, 2010, 12:30:11 PM »
Most rifle actions have not been stress relieved from the factory,  (I know that some rifle builders do stress relive the action before machining)  if you true an action that has not been relieved, then barrel the action, then bake a finish on, it is "possible" that the action will "move" as the stress is relieved.  If you just spent a bunch of time truing the action face and lugs that might not be a good thing.

Have you heard of a factory action moving during an oven cure at 350F?
Im not trying to be argumentative; Im just trying to understand the real harm in oven cure paint at its relatively low cure temperatures as it pertains to gun parts.   

Thanks again for your comments. 
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Offline Jeff

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Re: CERAKOTE Cure Oven
« Reply #11 on: October 31, 2010, 12:36:21 PM »
There's not much reason to go above 250 for Cerakote. I talked to them about plastic and wood and they said that 170-200 was enough if I extended the oven time a couple of hours.
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Offline berg

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Re: CERAKOTE Cure Oven
« Reply #12 on: October 31, 2010, 03:01:10 PM »
Have you heard of a factory action moving during an oven cure at 350F?
Im not trying to be argumentative; Im just trying to understand the real harm in oven cure paint at its relatively low cure temperatures as it pertains to gun parts.  

Thanks again for your comments.  

Nope, it is not something I have experienced, I don't have any kind proof that it could be a problem.  This information was passed along to me in an NRA rifle building class (tactical Rem. 700).  We all built rifles, we were told if we were going to use a bake on finish that we should heat (stress relieve) the actions prior to the blueprinting/truing/machine work on the action.  It was the instructors contention that factory rifles didn't suffer as much, as they have such loose tolerances any way..  I am not trying to start a stampede, not trying to step on any ones toes.  I understand that many rifle builders have different ways of doing things, and believe that different things are important.  The instructor builds rifles at TacticalOperations.com I think they guarantee a quarter minute of angle out of their rifles? (they also Cryo treat the rifles..)

I am not crying MOVIE in a crowded firehouse, if you have a stock rifle it shouldn't make any difference. (because the lugs and face of the action are not true in most cases anyway)........  It would not bother me to bake a finish onto my guns, but I never paid $3000-$4000 for any of them. just saying  :)
« Last Edit: October 31, 2010, 03:29:41 PM by berg »
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Offline J Mack

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Re: CERAKOTE Cure Oven
« Reply #13 on: October 31, 2010, 03:41:00 PM »
Berg

Again thank you for your input.
Im trying to gather as much information as I can on oven cure paint before I invest any more into the project.
Did the Tactical Operations guy mention what the process or temperature was to heat (stress relieve) the actions prior to the blueprinting/truing/machine/heat cure paint on the action? 
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Offline berg

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Re: CERAKOTE Cure Oven
« Reply #14 on: October 31, 2010, 03:49:09 PM »
To relax the existing stress in the receiver bake at 350 F for 2.5 hrs.  (the low temp will not affect the existing heat treatment) So, if the receiver were not stress relieved, and was trued up, then subjected to the heat of re bluing, or baking.. you "MIGHT" lose some lug to lug contact.  Once again, if your receiver has not been trued, it probably won't make a difference, most of the stock rifles we took apart were only making contact on a very small portion of the lug prior to truing. Just FYI, this is one of many, many ways you can change the accuracy of the rifle.  I had no idea you could screw up  affect the accuracy of a rifle in so many different ways. This took way to much time, my last post on the subject, I certainly did not mean to hurt anyone's feelings.  All this info. is free, so that is probably what it's worth.  GO SHOOT :)
« Last Edit: October 31, 2010, 09:02:00 PM by berg »
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Offline J Mack

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Re: CERAKOTE Cure Oven
« Reply #15 on: November 01, 2010, 10:24:44 AM »
This took way to much time, my last post on the subject, I certainly did not mean to hurt anyone's feelings.  All this info. is free, so that is probably what it's worth.  GO SHOOT :)
Berg

No hurt feelings on my side and I appreciate your input.
I hope me asking you to quantify your opinion did not hurt yours.
I know typing questions verses the spoken word sometimes comes across as condescending and I assure you that was not my intent.
I contend that for a nation to try to tax itself into prosperity is like a man standing in a bucket and trying to lift himself up by the handle.-- Winston Churchill
    I.N.T.E.L.L.I.G.E.N.C.E. is down! I repeat, we have no I.N.T.E.L.L.I.G.E.N.C.E.