Carbide form tool

How fast were you running the fly cutter?

jw

Greg,

This is a P.S. to previous message. As I reflected on your project, it occurred to me that 11 teeth on a 5.5" dia gear is not at all common. Usually, you would not attempt to cut less than 50 teeth on a gear of this size.

Pat

Greg Meyer wrote in news:dhuo0o$kb7$ snipped-for-privacy@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com:

You are going to need the correct grade of carbide, and you will need wheels made for grinding carbide, and most importantly, a dust collection system on your grinder to keep you from breathing the particles.

Anthony

Why not use an HSS Involute gear cutter? Using an endmill and fly cutter sounds very slow and inefficient, hence maybe thats why your single tooth form tool isn't lasting.

Tony

The standard involute cutters I have priced for this gear (I am in England) are going for about £1000.00. (about $1800.00 U.S.) The gear is a MOD 10 gear. As this is a one off project, that is a bit to much for my budget That is the reason I'm using the fly cutter approach.

I wanted to make a gear for my Rockwell 11 lathe gearbox, so I looked for an end mill in the shape of a tooth figuring to hold the blank on a spin indexer and just run it past what turned out to be a figment of my imagination. Never found such a beast in either the vertical or horizontal shape.

Considered making one by turning the profile in drill rod, milling it like they do taps, and hardening it. But I'm nowhere's near accomplished enough to do all that, so I made a ring gear out of a stock gear and glued it to the original after I turned the teeth off.

I guess the 'horizontal' version I envisioned was basically the usual gear cutter, but with a shank instead of needing an arbor.

Anyway, why aren't there such things for cutting gears with a vertical mill on an occasional basis?

Dick Hamm CompuFlex Nashua NH

Put the horizontal-mill gear cutter on a vertical-mill saw arbor.

Bearings Specialty off 101 is a Boston Gear distributor.

Jim Wilkins Segway Bedford NH

I think that's about 3 times too fast for HSS. I try to keep the cutter speed below 100 feet per minute and still occasionally burn up some import bits and end mills.

jw

If some of the old gear is in good condition you might be able to copy it. Set it up on the same shaft as the new one under a dial indicator which is parallel to the spindle. Put a ball end mill the same size as the indicator tip in the mill. If both are set to the same height you can raise the table to zero the indicator on each part of the tooth and cut the blank to the same height, then lower the table and rotate both gears a little. Once you have a series of parallel reference lines cut across the teeth you can file or grind the ridges between them, probably closely enough for an excavator. It's slow but I have used this method to copy several odd shapes on the lathe and mill.

jw

Thanks for the info Jim. I'll regrind the bit tomorrow and crank in the back gear... and keep my fingers crossed!

Regards Greg