Re: Brazing carbide

"David Billington"  wrote in message news:10nic1b$39582$1@dont-email.me...
It occurred to me when I was posting that last reply that you have to
deal with your electrical energy budget issues and that might make you
favour a different solution if available, not something I have to think
about so much with a 240V 32A supply in the workshop, more in the house.
Looks to be a nice furnace but what you have must be a lower temperature
model. 1500C would likely be a Mullite liner and SiC elements. AIUI SiC
are fairly easy to control with a phase angle controller and take care
of the change in resistance while heating and element ageing.  MoSi2
elements get more involved due to their characteristics  but not
required for 1500C usage.
I'd not heard of type P before as never run across one. Here in the
UK/Europe R and S are common for higher temperature applications, it
seems often US made stuff uses larger gauge K type to provide longer
life at elevated temperatures. For the Gallenkamp I use a K, the other
furnace I have an N type as more durable at the higher temperatures I
may have been using as that one goes to 1300C or would do if I replaced
the elements as they're old but it does what I require currently and
will make 1100C if needed.
Reseating socketed chips is one I use as well. I've saved a woman I know
quite a bit of money as when one of her temperature controllers gave a
thermocouple failure alarm I asked if she had pulled the guts and
reseated them, she wasn't aware you could do so RTFM. Others offered to
sell her a replacement. The Cal Controls ones I and she use and maybe
other makes allow the guts to be pulled from the panel mounting which
wipes the contacts and they had just become oxidised as only solder
coated so that was all that was required to get it working again, it's
now part of her yearly service routine. I've seen banks of them on
plastic extruder lines so the ability to hot swap the controller guts is
useful, saves having to pull the panel apart. IIRC those were on RS485
so the settings could be re-established remotely.
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I have 200A at 120/240V available if I want to pay for it, this house was built with electric heat for the promised cheap nuclear power we would soon enjoy. My retirement hobby is alternate energy and I practice living on it as much as is reasonable, and recording the usage.
The tube furnace may be the lower temperature model, labels are gone. I grabbed the first picture I saw. The missing original controller was apparently analog with optical sensing of the needle, and calibrated for type K, so the P t/c is a close but not exact match. Like much of my stuff it's from the 1960's.
All my (second-hand) industrial temperature controllers can be removed from the panel mount, mostly to change switch settings such as t/c type. I use some as remote displays of the wood stove. The surplus store sold regular wire cheaply by the pound, t/c wire expensively by the foot. When I explained that the X meant extension wire not suited for making thermocouples they gave me the per pound price on several large spools of shielded and grounded KX which isn't good for much else, and I ran it around the house.
Omega literature suggests using 14 gauge type K for longer life at high temperature. I think R and S are more for short runs within the instrument in the lab.