Which tool bit type for surfacing aluminum with a fly cutter?

[cnczoner]

Looking through the Enco catalog and they have styles such as AL, AR, BL, BR, C, D, etc, etc, etc. But not sure which style to use to surface aluminum. Also, am I correct in understanding that the C2 tips are correct for aluminum?
Thanks.
-Neil.

[Geof]

The type you choose depends on the angle that your flycutter holds the tool; you want clearance back toward the center of rotation so the tool is only cutting on the corner. AL or C will probably work; with A you need the L for clockwise rotation but with C it is reversible.

If your flycutter holds the tool either parallel to the shank or exactly perpendicular you would use GR or GL.

For cutting aluminum use the 370 grade which is for steel; this gives you a tool with a bit of top rake which is needed for aluminum.

When flycutting aluminum on a small machine where you have to keep the speed down because of balance issues I have sometimes found the best surface finish can be obtained by using HSS tools with an extreme top rake; almost so the metal is sliced off in a thin wafer.

[mxtras]

Agree with lots of positive top rake.

A radius on the nose helps, too. I prefer to hone the radius and the rake with a fine diamond hone - the smoother the surface the better. Especially on the rake - it helps to keep the alumiunum from galling and building up. Mist with ATF or WD-40 on the finish pass.

Scott

[cnczoner]

I am surfacing specifically to get a clean consistent finish on the top of (6061) aluminum plate.

I intend to get this flycutter from Enco... http://www.use-enco.com/CGI/INSRIT?PMAKA=225-3010
It says that it's counterbalanced -- not sure how much, but I can probably adjust the tool bit position to get a good balance. But it does not say how much it's angled, and Enco's support is very clueless as well. Is there any standard perhaps?

I'm looking through pages 153, 154 of Enco's online catalog and don't see anything with grade 370. Is that not carbide perhaps? Or would an indexable bit get me any better finish. If I were to choose from the Enco catalog, is there another recommendation that would be better than C2?

Currently I do use WD40 for all my milling, but I "engulf" rather than "mist" :-) I'm also looking into flood cooling soon, once I figure out my enclosure options.

[Geof]

The 370 grade is a carbide from a local supplier. Look for the carbide grade whatever it is called that is recommended for mild steel. AN insert cutter will probably not give you any better finish just cost more money.

[Mcgyver]

here are my thoughts on flycutter geometry and the common error if using a lathe knife tool, complete with illustrations I agree with the others, there is no advantage to carbide and the more acute cutting angle you'll get with hss will be advantageous.

http://www.cnczone.com/forums/showthread.php?t=28295