[TheForge] Fw: Forge temps

Sat Apr 4 09:21:51 EDT 2009

Bruce,  Measuring the temperature is one thing -- but to anneal S7 requires 
a very slow controlled cool down.  You going to stand at your forge for 24 
hours controlling the temperature of your metal?  If you have a programmable 
controlled heat treat furnace or kiln it can be done.  Most smiths don't 
have this equipment.

Heating S7 or H13 to critical and cooling in vermiculite will not work.  It 
will still be has hard as a whores heart.  Try it.

Dave

--------------------------------------------------
From: "Bruce Freeman" <freemab222 at gmail.com>
Sent: Saturday, April 04, 2009 12:17 AM
To: "Blacksmithing List Sponsored by ABANA" <theforge at mailman.qth.net>
Subject: Re: [TheForge] Forge temps

> First, go to this website:
> http://www.omega.com/toc_asp/frameset.html?book=Temperature&file=tc_colorcodes
> Look in the "Maximum T" column and select a thermocouple wire with the
> lowest suitable  maximum temperature.  I suggest K, for example. (Read
> the column "Comments Environment" for details that concern you.  For
> example, in a gas forge with the flame blowing out all the holes, the
> environment inside is "reducing" and a thermocouple that can't
> tolerate a reducing environment won't last long.  If the flame is
> completely inside the forge, then the environment is oxidizing.  If
> the thermocouple is only placed in the forge for short periods, this
> won't matter.  The thicker the wire , the less this matters, so favor
> the smaller-numbered gauges.
>
> Now consider either bare wire or ceramic insulation for the thermocouple:
> http://www.omega.com/pptst/BARE_SH_DH_OV_ELEMENTS.html
> For example, sh-1-14-K-12 will run you about $20 for a 1-foot length.
>
> You will need a millivolt meter.  This one from  HF is great, and
> despite the price on this webpage, has been selling for $3 at HF
> stores recently:
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899
>
> IF you can connect the thermocouple directly to the MV meter, then
> you're almost home free.  If not, then you need extension wire.   For
> precise measurements, you need extension wire of exactly the same
> composition as the thermocouple (so you don't make new thermocouples
> at the junctions).  This is only about $0.62 per foot, but they want
> you to buy 100 ft.  The gauge of this wire doesn't matter at all.
>
> SO, you might just keep the junctions at room temperature or close to
> it, and just use copper wire as your extension wire.  This will
> introduce errors, but these should be small if all extraneous
> junctions are at room temperature.
>
> Finally, you'll need a mV vs temperature chart for your type of 
> thermocouple.
> http://www.omega.com/thermocouples.html , or for the type K, measuring
> in deg. F:
> http://www.omega.com/temperature/Z/pdf/z218-220.pdf
>
> What this chart tells you is that at about 2000 F, the thermocouple
> will give you about 45 mV - easy to measure on the mV meter.
> You take your measurement, then come back to this chart to read the
> temperature.  Skip the "1" to "10" across the top, and just read mV in
> the "0" column, which will give you deg.. F within 10 degrees.
>
>
> On Fri, Apr 3, 2009 at 7:38 PM, Bob Willman <blcksmth at wcnet.org> wrote:
>> One could use Tempil sticks. They are accurate and reasionably
>> priced.
>>
>>
>> Bob Willman
>> Bowling Green, Ohio
>> The Eagle's Anvil
>> WB8NQW
>>
>> -----Original Message-----
>> From: theforge-bounces at mailman.qth.net
>> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Mark Novak
>> Sent: Friday, April 03, 2009 6:12 PM
>> To: theforge at mailman.qth.net
>> Subject: [TheForge] Forge temps
>>
>> How do y'all measure and control the temperature of your respective 
>> forges,
>> for accurate annealing? I don't have a pyrometer that goes over 1000ºF, 
>> but
>> I got ahold of some S-7 I'm going to use for center punches and which 
>> needs
>> to be annealed at 1500-1550ºF for 20-25 minutes (for a hand tool of this
>> size). I have no idea how hot my crappy atmospheric propane forge burns, 
>> let
>> alone how to maintain a somewhat consistent temp.
>>
>> Help!
>> Mark Novak
>> Fireworkspdx.com
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>
>
>
> -- 
> Bruce
> NJ
>
> The total lack of evidence is the surest sign that the conspiracy is 
> working.
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