[TheForge] A different needle question

[David E. Smucker]

Bruce, You are tempering, not heat treating -- while a tempil crayon can cool an item -- it can't quench it -- that only happens when cooling "quenching" from critical which we assume you have already done.  If the crayon melts then you have reached that temperature and you can now cool either fast or slow.

Dave Smucker
Brasstown, NC

-----Original Message-----
From: theforge-bounces at mailman.qth.net [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce .
Sent: Tuesday, October 22, 2013 6:46 PM
To: Blacksmithing List Sponsored by ABANA
Subject: Re: [TheForge] A different needle question

Not a bad idea, except that the tempil crayon would "quench" the heat in such a small mass -- and I don't know what effect that would have.  Had I the tempil crayons handy, I'd give it a try.

Bruce
NJ


On Tue, Oct 22, 2013 at 4:17 PM, Bob <blcksmth at wcnet.org> wrote:

>     I don't have a solution for the heating process but could tempil 
> sticks tell you when you have reached the desired temperature?
>
> Bob Willman
> The Eagle's Anvil
> Bowling Green, Ohio
> WB8NQW
>
> To the kindly influence of Christianity we owe that degree of civil 
> freedom, and political and social happiness, which mankind now 
> enjoys…Whenever the pillars of Christianity shall be overthrown, our 
> present republican forms of government – and all blessings which flow 
> from them – must fall with them.
>
> Jedediah Morse
>
>
> On 10/21/2013 6:24 PM, Bruce . wrote:
>
>> ​I am altering the eye shape of a few commercial needles.  They're 
>> too brittle to work without normalizing, but onc​ ​e normalized, they 
>> bend just fine.
>>
>> Now I need them hard again.  Well, dunking in water while at a red 
>> heat works for that -- but leaves them more brittle than ever.
>>
>> A tempering operation (to purple or blue, probably) is quite easy on 
>> a chisel, but even SEEING the colors on a needle is a challenge.  For 
>> one thing, there's no good surface to polish.
>>
>> I've tried a couple methods, all without success -- my toaster over 
>> doesn't
>> get hot enough, like, maybe 450 F, despite what the dial says.   (520 F =
>> purple, 540 F = blue, 590 F = peacock, according to one reference.)  
>> I tried heating an iron griddle to these temperatures and leaving the 
>> needle on it for about 5 minutes -- no luck.
>>
>> I considered using a salt or solder bath, but find no appropriate 
>> salt and that I'd need 80/20 to 85/15 lead/tin solder -- which is not 
>> readily available -- to get a liquid bath of the right temperature.
>>
>> I'm considering a sand bath or a furnace, using a thermocouple to 
>> monitor temperature, but as you can see, this is getting increasingly 
>> complicated for what should be a rather simple task.
>>
>> Hence, I'm soliciting suggestions how to temper a needle.  Any notions?
>>
>> Bruce
>> NJ
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