Inexpensive Fly Cutter

I want to get a fly cutter to use on aluminum, plastic, and possibly wood if I can. There are a couple old posts on this:

But not much in terms of actual results from people.

What I’d like to do is use one of these fly cutters:

Combined with a lathe insert from Harbor Freight:

This seems like a much more affordable way to fly cut materials rather than the $150+ Amana indexable surfacing bits.

Are there any problems with trying this out? Will those fly cutters handle 16000 RPM?

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That’s awfully fast for a fly cutter. They’re not particularly well balanced by design, I suspect there is likely some hazards here…


Second that. If that ever came apart at speed it would be deadly. Just don’t like the physics going on there.


That’s what I assumed as well, it’s just hard to know what things work in standard CNCs but won’t work in our CNCs. Thanks for the feedback. Perhaps this will work if I get a VFD spindle.

I believe it’s more of a rigidity concern (hobby machine Achilles)
The unbalanced nature of the tool spinning at RPM does not grant much in terms of wiggle room

Some guys are actually hesitant to use it depending on the size on standard knee mills (Bridgeport)
However, I have seen someone mention they have used it on a modded hobby machine. I would categorize it as a more advanced skill practice (wouldn’t recommend to a novice). If one was inclined to try - I would stay below 1.00" diameter swing.

Things can go wrong very fast.


Not so much rigidity as speed - 10k RPM is SCREAMING fast for something this size. These are usually run at a couple hundred rpm. It’ll probably run pretty smooth at 10k rpm, but it’s going to be really hard on the router bearings (out of balance), if it doesn’t bend something or throw it out of alignment, it’s likely to throw the tool out of the holder.


I have that same Micro Mark fly cutter with custom ground bits. I’ve only ever used it on wood. It cuts great. I don’t run it any faster than 5k rpm.


Good to know all that information. I figured it was more a balance thing with it hurting the router or the fly cutter. So if I get a VFD spindle, I’ll give it a try, otherwise I’ll stick to surfacing bits for routers.

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