What I would like to know, cutting through the BS, is it a good tool??, what are the limitations??, would it be a good match for a small Rockwell vertical mill, with a 1-1/2 hp motor?? Is it really capable of good finishes??.
I agree with
@higgite - it is a good tool. It uses the same insert found in Tormach's face mills but with only one insert, cutting forces from the Superfly is considerably lower than with a face mill. They developed the Superfly for use in low HP mills, notably their 440 CNC mill with only 3/4 HP, where it worked quite well so yes, I think it will work well on your Rockwell mill. My mill currently has a 1HP Baldor motor and I have yet to even slow the mill down with the Superfly.
The key limitation of the Superfly is that it will not cut to a shoulder. This has to do with the orientation of the insert. Otherwise, I am not aware of any other limitation when compared to any other fly cutter.
As you know, fly cutters are known to produce good finishes while also cutting flat accurate surfaces and the Superfly is no exception. How good is good? That depends. I know of no fly cutter, HSS or carbide, that produces true mirror finishes but the Superfly comes close in the hands of a good operator. What has impressed me is that the Superfly can do pretty good stock reduction while also finishing well. I've taken 0.070" depths of cut in aluminum with no significant degradation in the surface finish. I've done the same with 0.050" deep cuts in mild steel. Most fly cutters will show a reduction in finish quality with deeper cuts but the Superfly is able to keep up without seeming to strain the motor much at all, which I attribute to the insert geometry and the fact that you only have a single insert doing all the cutting. My spindle has less than 0.0001" TIR so it is fairly accurate; that may have something to do with the finish, dunno'.
I think Tormach did a good job choosing the insert for this tool. I've owned this tool for several years and have done a fair amount of work with it. I think I'm still on the same inserts for both aluminum and steel. Of course, this is in a hobby shop so I don't come close to what a production shop would do but having used carbide inserts for some time, I have been impressed with the tool life from these inserts.
I have found no imbalance issues at the speeds my mill can go. Admittedly, my top speed is only 2500 rpm but I've used the Superfly at 3" extension at this speed on aluminum taking up to 0.050" deep cuts without any sign of imbalance, significant vibration or slowing the motor at all. You would think that extending the cutter out would produce some vibration but at least at the speeds my mill can run at, this has not been an issue. Vibration on an extended cutter occurs due to centripetal forces so high speeds and big mass makes it worse. However, the Superfly only has a single cutter so mass is low. Centripetal forces also decrease with the radius so at the low speeds my mill can run at, vibration has not been an issue even with the cutter at full extension. I do admit that when I fully extend the cutter I do tend to reduce depth of cut most of the time, though.
The Superfly can handle a work piece out to 3" and surface it in a single pass so this is not bad for a tool that I consider cheap. It can be used effectively in mills under 1HP, finishes pretty well, uses inserts with a good usable life and can do significant stock reduction. So yeah, I think its a good tool. It isn't perfect - won't cut to a shoulder - but other than that, I sorta' like it.
I should mention that it finishes best when climb cutting. I normally rough the work in the conventional direction and take a finish pass in the climb direction and this works well for me.
Hope this helps.
