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Homemade carbide flymill

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vtsteam:
I've dulled a few of my HSS mills cleaning up some of the iron castings I've made lately. The iron is easily machined but the skin after casting often includes abrasives from the sand. I do grind them first with a hand grinder, but it's not possible to get everything.

I have no carbide tooling, but I do have about 100 new carbide inserts that were offered to me for $10 at the Bernardston engine show -- couldn't pass that up. When I got them home I was disappointed to learn that they were odd looking with a big radius instead of the usual flat diamond shape. But I thought they might find a place in a fly cutter of some sort.

Well today was the day to find out -- I decided to just do a quick and dirty experiment with a piece of hot rolled 7/8" rod as a mill, and just slot it to take an insert. I didn't even turn the scale off, since it was .874" already and I didn't want a loose fit in the mill collet.

I faced the ends in the lathe and just ran a little fine sandpaper to reduce the scale some. Then milled a .375" slot to take the insert. I held the insert about where it looked right and transfer punched a dimple for a screw. Then drilled and tapped the hole 8-32. I had a plain round head screw to fit, so put it all together, and gave it a spin in the mill.

It worked great on cast iron! I'm sure my geometry isn't optimum, and I will make a bigger, and better fly cutter paying more attention to the relief angles, but for now, this thing chews off the cast iron skin, which is all I ask. With 100 inserts to play with I should be set into the next century.  :dremel: :wack:

vtsteam:
Does a nice job, too. This was what it did to a back yard casting.

vtsteam:
Oh, one more thing. The inserts are beveled the wrong way, so I have to run the mill backwards. But that's simple.

I think when I make an "official version" fly cutter I'll mark it as a reminder. I definitely need that kind of thing  :doh:

tom osselton:
Good to see my son brought  home some spare inserts that I don't have holders for I'll Give it a go.

vtsteam:
Tom the hard part for me was figuring how to mount the inserts since I had no reference tooling for them. There's plenty of info on the net for the inserts themselves -- all the specs. But not for the tooling that holds a particular insert. I spent half a day puzzling it out and about an hour making it. It turned out to be the simplest machining imaginable -- just a simple straight slot. But before I realized that I'd machined a different holder, trying to run the insert flat along the radius of the mill -- as a more typical insert would require. Stuff is always obvious after the fact, but not always before.

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