Dan Pfeiffer on tue 14 oct 08
Does anyone know how to repair a type K pyrometer? Anyone done this?
I would think all you need is a brazing rod of the right type and you could
shorten the broke one and weld a new end on it. In looking on the web I
could not find any help.
Dan & Laurel
Paul Herman on tue 14 oct 08
Dan,
Last time I bought a K probe it was $12 I think. They last six or
eight firings in the wood kiln's three day firings. I recommend you
just buy a new one.
Best wishes,
Paul Herman
Great Basin Pottery
Doyle, California US
www.greatbasinpottery.com/
On Oct 14, 2008, at 6:44 AM, Dan Pfeiffer wrote:
> Does anyone know how to repair a type K pyrometer? Anyone done this?
> I would think all you need is a brazing rod of the right type and
> you could
> shorten the broke one and weld a new end on it. In looking on the
> web I
> could not find any help.
>
> Dan & Laurel
Michael Wendt on tue 14 oct 08
Dan,
Do not braze!
The bi metallic contact must remain
pure.
In a pinch, remove one or two of the
ceramic insulator segments, grind and polish
each rod where they will join and twist them
together using two pair of visegrips.
I have used an oxyacetylene torch to weld the
very tip after this treatment and it worked,
but I heard somewhere that hydrogen-oxygen
is used to assure the cleanest weld possible.
Can anyone confirm this?
Regards,
grip just
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
Dan & Laurel wrote:
Does anyone know how to repair a type K pyrometer?
Anyone done this?
I would think all you need is a brazing rod of the
right type and you could
shorten the broke one and weld a new end on it. In
looking on the web I
could not find any help.
Dan & Laurel
Sherron & Jim Bowen on tue 14 oct 08
Wouldn't type K thermocouples last much longer if they were protected by a
porcelain sheath designed to do the job? I think they cost about twenty
bucks.
JB
----- Original Message -----
From: "Paul Herman"
To:
Sent: Tuesday, October 14, 2008 8:16 AM
Subject: Re: pyrometer repair
> Dan,
>
> Last time I bought a K probe it was $12 I think. They last six or
> eight firings in the wood kiln's three day firings. I recommend you
> just buy a new one.
William & Susan Schran User on tue 14 oct 08
On 10/14/08 9:44 AM, "Dan Pfeiffer" wrote:
> Does anyone know how to repair a type K pyrometer? Anyone done this?
> I would think all you need is a brazing rod of the right type and you could
> shorten the broke one and weld a new end on it.
I would think as cheap as these thermocouples are, it wouldn't be worth the
effort.
If it has deteriorated from the heat over time there's probably not enough
good clean metal remaining to facilitate repair.
I believe the thermocouple is also made of two specific metals that create a
slight electric current when heated. Placing a braze weld between them may
prevent the proper current to get a reading.
And besides, wouldn't the braze melt in the firing?
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Steve Mills on tue 14 oct 08
Dan,
I wouldn't bother; Type K Thermocouples have a very short accurate life, are only rated to 1200oC, and are relatively inexpensive compared to types R and S.
It's just not worth the effort as it'll wind up more expensive repairing than getting new!
Steve
Bath
UK
--- On Tue, 10/14/08, Dan Pfeiffer wrote:
From: Dan Pfeiffer
Subject: pyrometer repair
To: CLAYART@LSV.CERAMICS.ORG
Date: Tuesday, October 14, 2008, 2:44 PM
Does anyone know how to repair a type K pyrometer? Anyone done this?
I would think all you need is a brazing rod of the right type and you could
shorten the broke one and weld a new end on it. In looking on the web I
could not find any help.
Dan & Laurel
Hank Murrow on tue 14 oct 08
On Oct 14, 2008, at 9:54 AM, Sherron & Jim Bowen wrote:
> Wouldn't type K thermocouples last much longer if they were
> protected by a
> porcelain sheath designed to do the job? I think they cost about
> twenty
> bucks.
Jim is quite correct, the protection from a reduction atmosphere will
be a big help. Nevertheless, there is no substitute for a type R
thermocouple if one needs accurate measurement of high(above cone 5)
temperatures. The Doorless Fiberkiln at Shadbolt Arts Centre in
Burnaby BC has an OxyProbe(which uses a type R Platinum/Rhodium
thermocouple) has gone 1200 firings by now with one repair to the
probe. It depends upon how much you need longevity, repeatability,
and accuracy from your thermocouple. Of course, cones 9, 10, & 11 are
used to determine heat work at the end.
Cheers, Hank in Eugene
www.murrow.biz/hank
William & Susan Schran User on tue 14 oct 08
On 10/14/08 12:54 PM, "Sherron & Jim Bowen"
wrote:
> Wouldn't type K thermocouples last much longer if they were protected by a
> porcelain sheath designed to do the job?
Depends on your firings and your clay and your glaze materials, and then if
you direct vent the kiln during firing.
Any off-gassing and/or fumes can degrade the thermocouple, the elements and
the bricks.
A ceramic sheath can help, but if you are using a programmable controller,
then you will need to compensate with a thermocouple off-set to allow for
the heat to work though the sheath to the thermocouple.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Dan Pfeiffer on tue 14 oct 08
I have not found new 8 gauge pyrometers to be all that cheap and I need to
fix/replace 5 of them so it does add up.
If you look at the end of a new one you can tell that they have been welded
in some form and I would guess it would need to be with the same type metal
as one of the wires. All the ones I have are a lot longer that is needed and
only the last 3 inches seem to be getting very hot, lots of metal left to
work with if I can get the joint remade. I may try a forge weld on one and
see how it works.
Dan & Laurel
>>>I would think as cheap as these thermocouples are, it wouldn't be worth
the
effort.
If it has deteriorated from the heat over time there's probably not enough
good clean metal remaining to facilitate repair.
I believe the thermocouple is also made of two specific metals that create a
slight electric current when heated. Placing a braze weld between them may
prevent the proper current to get a reading.
And besides, wouldn't the braze melt in the firing?<<<
Paul Herman on tue 14 oct 08
JB,
The K probes I refer to below ARE in a porcelain tube. I think it's
the long firings (and firing to cone 11-12) that cause them to wear
out so quickly.
Hank, I fire only twice a year, so the type R thermocouple would not
be cost effective for my kiln.
best wishes,
Paul Herman
Great Basin Pottery
Doyle, California US
www.greatbasinpottery.com/
On Oct 14, 2008, at 9:54 AM, Sherron & Jim Bowen wrote:
> Wouldn't type K thermocouples last much longer if they were
> protected by a
> porcelain sheath designed to do the job? I think they cost about
> twenty
> bucks.
> JB
>
> ----- Original Message -----
> From: "Paul Herman"
> To:
> Sent: Tuesday, October 14, 2008 8:16 AM
> Subject: Re: pyrometer repair
>
>
>> Dan,
>>
>> Last time I bought a K probe it was $12 I think. They last six or
>> eight firings in the wood kiln's three day firings. I recommend you
>> just buy a new one.
>
Sherron & Jim Bowen on tue 14 oct 08
We use our pyrometer to judge the temperature and the rate of climb. We have
no controller. We use cones to determine when the firing is complete.
Reading seem to be instantaneous in that we can change the damper or the
burner setting and get immediate feedback through the sheath.
JB
----- Original Message -----
From: "William & Susan Schran User"
To:
Sent: Tuesday, October 14, 2008 1:34 PM
Subject: Re: pyrometer repair
> A ceramic sheath can help, but if you are using a programmable controller,
> then you will need to compensate with a thermocouple off-set to allow for
> the heat to work though the sheath to the thermocouple.
>
> Bill
Sherron & Jim Bowen on tue 14 oct 08
Watch eBay. Last year there was a seller with dozens of them that were
eighteen inches long and sold for as low as a few dollars on a Dutch
auction. I bought ten.
JB
----- Original Message -----
From: "Dan Pfeiffer"
To:
Sent: Tuesday, October 14, 2008 1:47 PM
Subject: Re: pyrometer repair
>I have not found new 8 gauge pyrometers to be all that cheap and I need to
> fix/replace 5 of them so it does add up.
> If you look at the end of a new one you can tell that they have been
> welded
> in some form and I would guess it would need to be with the same type
> metal
> as one of the wires. All the ones I have are a lot longer that is needed
> and
> only the last 3 inches seem to be getting very hot, lots of metal left to
> work with if I can get the joint remade. I may try a forge weld on one and
> see how it works.
>
> Dan & Laurel
>
>>>>I would think as cheap as these thermocouples are, it wouldn't be worth
> the
> effort.
> If it has deteriorated from the heat over time there's probably not
> enough
> good clean metal remaining to facilitate repair.
> I believe the thermocouple is also made of two specific metals that create
> a
> slight electric current when heated. Placing a braze weld between them may
> prevent the proper current to get a reading.
> And besides, wouldn't the braze melt in the firing?<<<
>
>
Ivor and Olive Lewis on wed 15 oct 08
Dear Michael Wendt,
When I was in the Big Steel business we had a lab dedicated to
Pyrometry. Kept about half a dozen technicians and a PhD occupied.
Yes, they used an Oxy-Hydrogen torch to do all of the welding on the
thermocouples.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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