carbide form tool

[meyerga00]

Greetings all,

I'm in the final stages of milling a large spur gear (5.5" dia 11 tooth) for repair of an old excavator. I'm using SAE 9310 stock (also nkown as EN 36 or BS 970) which is a nickel/chrome steel. My plan was to use a 5% cobalt fly cutter ground as a form tool to finish cut the final tooth shape after hoging out the majority of the stock with a carbide end mill. The carbide end mill worked great but my fly cutter lasted one tooth (groan) My thought is to produce another fly cutter but silver solder a carbide blank in place as the cutting edge and then grind it to the right form. I've got no experience grinding carbide. Any tips, suggestions or flame mail.


TIA

Greg
[e-mail]

[SteveW]

Meyerga,

I while back I was into flycutting a CI casting and it knocked to tip of the HSS tool after the second hit after which the noise just got louder. I asked the question "can I use tipped tools". Everyone said No, I'd knock the tips off. In the event I was at an MEX and took a flyer with a right cutting brazed tip lathe tool (from Chronos). It was nothing special, just the standard blue shank tool from a set of cheap brazed TCT tools to fit the flycutter holder (from...).

The result was brilliant and I didn't loose the tip and it's still going. Later someone added a bit of history to the 'fragile' TCT story which sort-of supported my success.

As for changing the shape of the tip: I use the diamond laps (again from Chronus) to shape them. I use from fine to medium and use them like files, tool in the vice. They are VERY effective on TCT so you need to check often.