how do you deal with work hardened steel?

[tonyjohnson]

I used poor technique when I drilled out the existing hole in my nosegear strut in preparation for reaming it for the taper pin modiciation. I drilled too fast and too long. I ruined my brand new bit, and had to buy another bit with which I finished the hole properly going slower and at slower speed using lots of oil.

The excessive heat seems to have work hardened the hole so that the taper reamer will not cut.

The reamer did cut initially but ceased cutting when it got to the part of the hole that seems to be work hardened. I tried for hours turning the reamer by hand. I tested the reamer by doing a couple of turns with it in the other side of the hole, and it works.

My guess is that the portion of the hole that is work hardened is about 1/2 to 3/4 of an inch long.

Unless I can come up with a better plan, I will probably try running a size S bit (.004 wider than 11/32) in the hopes of removing the area that is work hardened.

Any ideas about how to address this problem?

Thanks

[captainron]

Get a new reamer and NEVER turn it backwards, even a tiny amount. It will instantly dull it.

[tonyjohnson]

Ron,

The reamer works fine. It is brand new and I have never turned it backwards, not even a little. It cuts other steel just fine, I tested it.

[rv9aviator]

You might try a cobalt reamer instead of a high speed reamer and turn it fairly slow. Use pipe threading oil to lubricate the reamer. Use the stinky black stuff that smells like sulfur if you have some. The best thing would be a solid carbide reamer but they are pricey.

[asav8tor]

What size reamer do you need? I might have a cobalt one you could use.

[tonyjohnson]

The reamer that I am now using is a brown and sharpe high speed steel taper reamer with straight flutes size 3. If I recall correctly, Jim Ellis who seems to know his stuff, says that a size 4 reamer will also work.

I am turning the reamer by hand although it is a high speed reamer. I greatly appreciate the offer of the use of a cobalt reamer and that might just be the ticket here.

[Mark Burns]

Tony,
I'm not sure you work hardened it. I think you just got it too hot and tempered the steel. Sort of re heat-treated it to a new level of hardness.
At any rate the result is the same, now it's too hard to ream with normal methods.

The metal probably only got hard a few thousands deep. Do you think it happened all the way through the hole or just it one spot or two?

My suggestion to to get a stone on a dremel tool and grind the hole in the areas you think are hard. Just take off a few thousands and try the reamer again. By grinding it some the end result may be that once reamed the taper pin may sit too deep. Hopefully you have some to room to play with.

Good luck and keep at it. Don't let it win, it's only metal

Mark

[asav8tor]

Most of the stuff I have I got from Boeing. I need a decimal number to go check for the size you need.

[tonyjohnson]

Mark, I used the term "work hardened" because it was the only term I knew....I think your explanation is correct, and as you observed it is the same result. I think that only a portion of the hole is affected, probably just the spot where I overheated it enough to kill the drill bit. I tested the area where the pin will exit and the reamer cuts fine there. Thanks for passing along your suggestion. I will give that a try.

If that does not work out and if asav8tor has a cobalt reamer to lend me I will try that.

Does anyone know the decimal equivalent of a #3 reamer?

[Rick6a]

Originally Posted by tonyjohnson

......Does anyone know the decimal equivalent of a #3 reamer?

Tony,

I believe a #3 reamer is .4375 or 7/16".