5 hours ago, Patcon said:

Looks like the depth is less than 0.100" on several of the cranks that I looked at

Two flats is fine, if that's easiest

  .100 deep it shall be. And two flats.

Would it be any easier to make it this way?

The inner and outer sleeves would have to be welded (plug weld through the flats), but it might obviate using a broach or a shaper.   Since I have neither, I'd have to make it something like this.

The inner sleeve could be turned to a thickness of .125 to clear the key.

Creative thinking, but having the shaper (and hopefully a broach close to what I need?) I don't think it would save me much.  I'd still have to put the slot in the inner piece and for that, I'd use the shaper. Would be a little easier since I could do it as an external operation instead of internal, but not enough to warrant two pieces and welding.

I'm not stifling the creativity though! Certainly a way to make use of the tools you have to accomplish the task in a different way.  

And I like your pic a lot. I wish I had a CAD package I could use to whip up stuff like that! I'm still drawing by hand!  LOL!

So about these two opposing flats... How wide does your wrench open?

I'm running Inventor 2020.  If I'm making anything at all, I'll create the models first.  I have found my productivity is significantly greater as opposed to figuring it out as I go.  Also, my material waste due to errors and rework time dropped to near zero.  Mostly, its benefit, as I'm sure you know, is as a design checking tool. 

If there's something your working on and need to "see" it in 3D, I'm happy to help (I think! ?).  PM me.

13 hours ago, Captain Obvious said:

So about these two opposing flats... How wide does your wrench open?

That seems sort of personal...

Appears to be just a shade over 2  1/2"

 

If those calipers are still handy, would you mind measuring the damper hub OD?

9 hours ago, Patcon said:

That seems sort of personal...

I said wrench, not "wench".   

Thanks for the data. I'll make sure my opposing flats are within that range. I had already started aiming at 2", but since your wrench will go bigger, I might too. Less metal to remove.

10 hours ago, ETI4K said:

If there's something your working on and need to "see" it in 3D, I'm happy to help (I think! ?).

Thanks much for the offer! I'll keep in mind.  

Now you all know I love to machine stuff but it occurs to me maybe taking an old crank gear and grinding flats on it would be an easier way to go. 

 

Interesting thought but I am not sure that would work that great. The crank gear is really not that thick when measure at the bottom of the grooves. Even thinner at the keyway. i already popped the balancer open that we had welded an arm to. Plus if yo grind flats, you will have to grind pretty deep to get a reasonable surface for the wrench to bear against. Now on an unfrozen motor, it would probably work fine. Although I would not want the press fit of the gear

Derek, That gives me a thought...  Instead of spending time on the nut portion of the equation, how about spending it on the TOOL portion.

Build a chain wrench designed to grab the teeth on the crank sprocket. Like this, but designed using a length of two row Nissan timing chain:

That'll be a project for the next guy...