[Shop-talk] Annealing Copper bars

[Donald H Locker]

Cool! (so to speak.) I would have thought more insulation would have
been required, but it sounds like that is sufficient.

Donald.
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On 2020-08-08 6:50 p.m., Jack Brooks wrote:
> Insulation - BINGO!  Great thought Donald!
> 
> I underestimated copper's heat transmission rate.  Using propane, I could not get a 1/8 x 1 inch x 8 inch bar to get to glow with the bottom of the bar clamped in a vice.  I decided to try "Insulating". 
> 
> I laid a 3 inch long copper bar (typical busbar length) across the teeth of two sections of a coarse hack saw blade clamped off to the side of my vice.  There is almost no contact between the copper bar and these supports, only across the tips of the teeth on the two halves of the hack saw blades, so maybe a dozen pinheads.  With this arrangement and with a partially-dark room, I could just barely see the red glow in the copper. After a quench, the copper bar was soft!
> 
> I now have a method.  Now I have to insure that I can clean up the contact surfaces well without affecting the flatness and I can go forward with softening the real busbars.
> 
> Thank you everyone for a fun adventure in learning,
> 
> Jack
> 
> 
> -----Original Message-----
> From: Donald H Locker <dhlocker at comcast.net> 
> Sent: Saturday, August 8, 2020 10:14 AM
> To: Jack Brooks <JIBrooks at live.com>
> Cc: shop-talk at autox.team.net
> Subject: Re: [Shop-talk] Annealing Copper bars
> 
> The temperature that the copper reaches is controlled by the rate at which the heat escapes it vs the rate at which heat is added to it, and finally by the temperature of the flame.
> 
> An oxy-fuel torch adds heat quickly, so the rate at which it is lost is less of a problem. Propane/air is not as hot as oxy/fuel, but they're both plenty hot enough.
> 
> I would expect a propane torch to do OK as long as your copper bar is reasonably well insulated from the outside world - how about [nearly] burying it in vermiculite? Add heat in the middle with the rest of the bar pretty well buried and it should get reasonably hot throughout. You could use a Tempil Stik or an IR thermometer near the ends to see when it has heated sufficiently.
> 
> It would be easy enough to then pick up the bar with pliers or tongs and dunk it.
> 
> At least I'd try that before tempting the fates with Mrs. Jack's oven.
> Donald.
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> 
> On 2020-08-08 12:06 p.m., Jack Brooks wrote:
>> I disagree to some extent on the water/oil quench vs. air cool, from 
>> text and experience.  I’ve done both with oil pan drain plug washers 
>> and while there may be a difference, it’s minor making the two methods 
>> interchangeable in my experience, especially if I am trying to go from 
>> half hard to a softer condition.   A quench is the ultimate way to 
>> soften, but just getting it up to temperature makes a huge difference 
>> in hardness.
>>
>>  
>>
>> https://en.wikipedia.org/wiki/Annealing_(metallurgy)#:~:text=In%20the%20case%20of%20ferrous,quickly%20by%20quenching%20in%20water.
>>
>> https://www.wikihow.com/Anneal-Copper#:~:text=You%20quench%20carbon%20steel%20to,the%20resulting%20crystalline%20structure%20is.&text=So%2C%20to%20anneal%20a%20hardened,heating%20it%20red%20anneals%20it.
>>
>> The question remains, lacking an Oxy torch, thoughts on the clean 
>> cycle of a home over or any other suggestions?  I may talk with my 
>> body guy about using his Oxy torch.  That was a good suggestion.
>>
>> Thanks,
>> Jack
>>
>> *From:* Shop-talk <shop-talk-bounces at autox.team.net> *On Behalf Of 
>> *Pat Horne
>> *Sent:* Saturday, August 8, 2020 8:44 AM
>> *To:* John Innis <jdinnis at gmail.com>
>> *Cc:* shop-talk <shop-talk at autox.team.net>
>> *Subject:* Re: [Shop-talk] Annealing Copper bars
>>
>> So, referring back to the OP about using the oven to anneal the bars, 
>> it WOULDN’T be a good choice.
>>
>> Peace,
>> Pat
>> Pat Horne
>> We support Habitat for Humanity
>>
>> On Aug 8, 2020, at 10:03 AM, John Innis <jdinnis at gmail.com 
>> <mailto:jdinnis at gmail.com>> wrote:
>>
>> This matches my understanding as well.  Brass and copper soften when 
>> quenched.  Steel and Aluminum harden when quenched.
>>
[snip]