Rotary Cutter How do I ream out hardened steel?

[sandman2234]

The O/P doesn't have his location listed, but if he is anywhere near Jacksonville, Florida, I would be happy to set the gearbox up in the mill and do it the right way (or should I say the way he seems to be leaning).
I am with Soundguy, as his is a much better way of fixing the problem in a much easier way.
Several people mentioned bushings, but what about a shoulder bolt so that eliminates one of the bushings, and some of the slack.
For those with the idea that adjusting the slip clutch is the right way to fix this problem, it isn't. Yes the slip clutch needs to be properly adjusted, no doubt, but the slack in the yoke is allowing a headstart towards slamming into the bolt, which only removing the slack is going to fix.
Again, I would drill out the yoke. If you make a mistake drilling it, then the next thing to do would be to replace the yoke with the correct one this time, something the O/P is apparently trying to keep from doing by simply drilling it to fix it. If you attempt to drill out the shaft and you make a mistake, an imput shaft or a replacement gearbox is not going to be a $20 item...like the yoke. (guessed at the price)
David from jax

[SPYDERLK]

I would drill a hole through one side then slip it on the shaft using the shaft to center the second side by drilling through both. If you sincerely want to drill the hole in the shaft larger, I would use a bridge reamer. The long taper prevents binding and they will cut hard steel easily.
Attachment 302775

Good idea. The alignment issue is quite critical to assure both bolt crossings share load. Youre still left with 3/8 shear tho and OP thinks this is not enuf. Also, any shaft/collar play from wear will still be there. The overhang of the slip clutch serves to aggravate this.
That strikes me as applicable for short holes. A tapered continuous cut an inch and a half long in hard stuff would tend to twist it off.
larry

[City Farmer]

It might only be case hardened. I'd try taking a grinder to it and see if you can get to anything soft about .060" depth then drill. Option 1) Grab a 1/2 carbide end mill (ball nose might work better) and put it in your drill and go for it, after you open the hole a little bit with a grinder. 2) Put a taper on a pin with some layout ink and grind it in, it will go a lot faster than you think. Save your money don't mess with cobalt or hss drill bits, there not gonna do it if its hard all the way through.

[SPYDERLK]

End mills are more fragile than drills owing to their side cutting purpose. The angle of the cutting edges is more acute. That means less support of the edge and easier cracking.

[orezok]

That strikes me as applicable for short holes. A tapered continuous cut an inch and a half long in hard stuff would tend to twist it off.
larry

In heavy construction we use them for high tensile beams with flanges of over 1-1/2". To be on the safe side, you could approach from both sides.

[Soundguy]

wow...

[sandman2234]

wow...

Yeah, the answer seems so easy, and yet...
David from jax

[Soundguy]

Yeah, the answer seems so easy, and yet...
David from jax

yeah.. 4 pages now..