Carbide form tool

Oct 04, 2005 3 Replies

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 snipped-for-privacy@hotmail.com


nkown as

silver

Greg,

Obviously you need a 'green grit' wheel, but beware of the wide range of carbide materials there are out there. As inevitably you will have to make interupted cuts you need a tough grade which many of the inserts are not.

AWEM

Hey Andrew,

How goes it??? We need to cast some metal some day soon! The carbide blanks I've been able to fine are all called Grade C-2. From what I understand the classifacation C-2 covers a pretty wide area as far as the grain size of the carbide ect ect ect. Any pearls of wisdom.

greg

tips,

Greg,

Yes you need to stop sewing up horses and I need to stop having shops burnt down and we might just find time to do some more casting - I still have a vast pile of cast iron sash weights waiting for you !

C-2 carbide is for non-ferrous as I understand it - though as you say its a bit of a 'bucket specification'. I'd feel happier with C-6 which if I'm right is for alloy steels but your main problem with almost any grade is those interupted cuts. As I said in my email yonks back, grinding to final size is the best way if it can be arranged.

If you have to fly cut you are forced to take small nibbles at a time to preserve the carbide but you need them big enough to not just rub - so it's a bit of a compromise. You need a really ridgid set up and you may well get away with it.

Andrew

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