Shaking my tin cup....

[trbig]

I don't believe the 300 degree cycling will accomplish anything useful.

You might also note, that an extremely important step in all of this is to get it to just 300 degrees to the negative. Yeah, that's cold.. but it's only 300 degrees. I know it doesn't sound like much, but after reading, this 300 degree cycling in the oven seems to be an extremely important step in reduction of the brittleness of the steel.

Tod

[oseaghdha]

You might also note, that an extremely important step in all of this is to get it to just 300 degrees to the negative. Yeah, that's cold.. but it's only 300 degrees. I know it doesn't sound like much, but after reading, this 300 degree cycling in the oven seems to be an extremely important step in reduction of the brittleness of the steel.

Tod

Yah,
I was referring to the oven drill.
300 seems low for a draw or temper.

[trbig]

I realized that's what you were saying.. What I was pointing out is that even though 300 degrees above zero doesn't seem like it would do much... just 300 degrees below zero sure does. I'm no chemist by a long shot, but you can read about the chemical changes with just these temp changes.

You are starting the process with a tempering and finishing it with the cold process. It gets all the molecules aligned right. The heat tempering is the biggie.. that's the haircut. The other steps are just the combing things into place afterwards.

Tod

[red bandit]

Reaching -300 or + 300 is only part of the process. The rate at which the part is brought back to room temp. is just as important if not more.

This is just one example. We used to have parts raised to 1900 deg. for heat treating and brought down 100 deg. per hour. You can't do that in your garage. Not that you would have to do this with your gears.

Queching in oil does work, provided you have the proper material to start with. But a heat treating shop has a LOT more control over the entire process. Not saying what you are attempting won't work. Make sure you find out all the variables before you start. Best wishes.

[TopCatGr58]

Hey Tod,

This rehardening process was recently discussed in the YAHOO tech group, TKAT....well seasoned machinist and such posted some good info on heat treating and such, you might want to look up the discussion, was just a week ago, so it should be very close to the top of the thread/posts pile.

I would like to find a process that the common folks who have to do the dremmel at home could do some simple form of case hardening at home, and also knowing or confirming the heating and slow cooling to normalize it afterwards would be good to know...for an addendum to the Dremmel fix tech tip.

Thankfully mine has held for some 8 years, but only some 16k miles. I don't HAMMER mine hard all the time, but do ride it spirited at times.
T.C.

[xschop]

reheating after the dremel

It may be that the carbon reintroduction would be the ideal treatment since you remove the case layer when you Dremel on it.....The tempering and/or cryo treating would be extra insurance.....

[trbig]

TC... I don't have a clue about Yahoo discussion groups. I wouldn't even know where to start looking for it (Yeah yeah.. go to Yahoo first.) lol.

Tod

[thewiz]

There is also a process ..

called Tuftriding that puts a scuff resistant 'coating' on the parts. It was done with cyanide back in the day. Typically it is/was done to cranks and cams but it might be effective for gear dogs as well ... but probably best after heat treating or nitriding.