But it wants to be a left hand tool because of the geometry of the holdet. At least mine is. If you can find one that uses the obtuse corners of the usual diamond tool you can use up all the blunt inserts youve hoarded.

If you already have the brazed ones then they do work, based on having used them myself in the past.

But as your needs seem to be for production work then a face or shell mill will be a lot faster.

I use round carbide inserts in my fly cutter. I use standard RCGT0602 polished inserts for aluminium stock and 12mm inserts of an unknown spec for steel. I reground the 12mm ones so the cutting face is flat, it seems to work ok. I made the shanks from mild steel.

For the best results, it really depends on the carbide grade your using. Especially today, there’s specific carbide grades formulated with different binders and sintering processes that are much more resistant to chipping or breakage during interrupted cutting. For most here, that might still be a lower priority than it may be in a commercial environment. But it’s still worth understanding that there’s some carbide formulations that will work and be a lot more durable depending on how it’s being used. If it were me and I really did want to use carbide in a fly cutter for steels or harder metals. I think I’d spend the extra and buy the correct left hand tool that takes replaceable tips.

But a fly cutter WILL NOT do or ever replace what a proper face mill can without doing permanent machine damage over long term usage and larger depths of cut. That’s inarguable and well proven. The tool itself can and will take much larger depths of cut than I limit mine to, my spindle bearings and splines can’t, and for logical reasons. Then do the simple math on top of that. One single cutting tip at .002″-.004″ feed rate per revolution, or the exact same using 4 or more cutting tips on a face mill that can also take those larger depths of cut if that face mill is properly sized for the available horse power and mill rigidity.

What I have is no longer being sold or I’d link to the manufacturer. But just like Vic mentioned he’s using, the very best fly cutter I’ve used so far was designed for round carbide inserts. And on mine, the tool shank insert radius was machined and tilts the tip backwards a further few degrees for an even higher positive rake angle than the inserts already have. So it seems to cut smoothly and with very low pressure. It’s also an extremely cost effective tool considering you can partially rotate the insert at least 10-12 times or more as the insert edge dulls or very rarely might chip.

For mine, I’m using Kennametal brand inserts. I’ve no idea how any of the much cheaper no name inserts may or may not work for there surface finishes or long term durability. I also get noticeably better surface finishes than any other HSS or braised tip carbide I’ve tried so far. Quite obviously rpm, depth of cut, feed rate and metal hardness it’s cutting all plays a part in a cutting tools edge and maximum life span.