Drilling Dewalt gear for Fisher Price

[sanddrag]

How do we drill (then ream) the dewalt gear to press on the fisher price shaft? We went in with a ~.120 drill and it made lots of noise. It seemed like it was working, but maybe half way through it broke. The gear seems like a very hard material. Any ideas?

[Kevin Sevcik]

How do we drill (then ream) the dewalt gear to press on the fisher price shaft? We went in with a ~.120 drill and it made lots of noise. It seemed like it was working, but maybe half way through it broke. The gear seems like a very hard material. Any ideas?
Very hard indeed. I chucked the pinion in a lathe and went throught at around 1200 RPM with a brand new bit a little under .125. Then you want to use atleast a .1250 reamer, if not slightly larger. You'll never get the gear on without bending the shaft if you use anything smaller than a .1250, though.

[Joe Johnson]

I definitely don't recommend using a standard drill to do this job.

Even a lathe is trickier that I'd like (though with a very tiny boring bar & small cuts you can do it reliably).

I am a big fan of wire EDM. Fine a local source or use the one listed in the NBD whitepaper.

Joe J.