52100 (Aldo's) alternate heat treat= Epic Fail !!!!!!

[NickWheeler]

I'm not going to claim to anyone that 1550 is the magic number it's just what I settled on with my setup. I'm going to do another large batch soon and am using the same steel and will do more experiments and will not decide on based on a number but by results. And unless you have the exact same setup with the exact same thermocouple, in the exact same state of decay then you will have a different temp reading than me when you do yours. You can only tell if it was good enough by testing your blades and adjusting accordingly.

Kind'a funny... I agree with Matthew AND Jimmy on this...

The idea of using a process that is standardized is so wonderful in theory, and something that I shoot for.

But I also know that there always seems to be differences between "theory and application."

1475F has worked GREAT for me, in my shop, with my equipment. It didn't work worth a tinker's dam for Jimmy... and I believe him because he obviously went through all the steps to try and make it work, and then thoroughly tested the results. :thumbup:


Jimmy- one question though: what did you mean about stripping the wires on a thermocouple? My thermocouples have a quick-disconnect, so I think that's probably why I'm not visualizing that.


With any of this stuff, at the end of the day, you have to test your process and the results to have confidence in what you're doing. The mechanical engineer in me wants to believe in numbers... but the redneck tinkerer/builder/fabricator in me knows that numbers only get you so far....

 

[jimmyseymour]

Kind'a funny... I agree with Matthew AND Jimmy on this...

The idea of using a process that is standardized is so wonderful in theory, and something that I shoot for.

But I also know that there always seems to be differences between "theory and application."

1475F has worked GREAT for me, in my shop, with my equipment. It didn't work worth a tinker's dam for Jimmy... and I believe him because he obviously went through all the steps to try and make it work, and then thoroughly tested the results. :thumbup:


Jimmy- one question though: what did you mean about stripping the wires on a thermocouple? My thermocouples have a quick-disconnect, so I think that's probably why I'm not visualizing that.


With any of this stuff, at the end of the day, you have to test your process and the results to have confidence in what you're doing. The mechanical engineer in me wants to believe in numbers... but the redneck tinkerer/builder/fabricator in me knows that numbers only get you so far....

On the side that does not disconnect and goes straight to the controller. Those wires are supposed to be calibrated by the manufacture to give a certain reading based on the resistance. They usually only have a little bit of wire showing so sometimes to get a good connection you have to strip the wire a little. If you cut the wire you have changed the resistance, and thus your readings. I screwed up the first time I was changing thermocouples in a GE frame 7FB gas turbine and stripped and cut what I thought was just a little amount of wire and put in the new thermocouple. Later we could not bring the unit online as the temperature differential between that one can and a few others was to much and it's automatic trips and safeties prevented it from coming on line. They finally called out a real electrician and I showed him what I had done. As soon as I told him I cut the wires he told me to stop that we had just screwed up big time. So he had to go to the controller and recalculate all the readings to reflect the new resistance of the wires. A few hours later we were online. The next outage we changed out all the wiring and went with thermocouples that were quick disconnect so no one else would make the same mistake.

You cant cut any wire at all on this side without it affecting your reading. Now if you have a controller you can communicate with you can re-zero it at the new resistance like we did.

 

[Willie71]

Great discussion guys! I didn't get a lot of shop time in this weekend, so my test coupons are still waiting. What I do know is I get Rc50 prior to grinding the decarb off, and Rc66 once the decarb is gone.for me in my shop with my equipment, 1475 is what works.

 

[jimmyseymour]

Here's a better picture. My units only came with the bare wire and no thermocouples. Since they seem to run like a champ I can only hope that they programmed the controller with the proper resistance for the wires and didn't just cut some wire and screw one side in and say that's good enough. On some wires when you are trying to get them through the plastic and very small holes you sometimes mangle the ends and people just cut and strip a little more wire so they can get a good connection. Since their quick disconnect I only have to do this once. The old style you would have to do this over again every time you changed your thermocouple.



Re-reading this thread I did notice their was something in it that I did not do. I did not quench in water as I'm using salt pots and didn't want to take the chance of introducing any water. That may have resulted in me needing to use a higher temp. I'll try with the next batch and just make sure it bone dry before the next thermal cycle and see if the results are different.