Tormach SuperFly Cutter

I have a PM935 mill and have been thinking of buying a Tormach Superfly. I would use it in a 3/4" R8 collet or an ER40 adapter. BTW, the inserts are ridiculously priced from Tormach or LMS, so I'd buy them on ebay.



I searched here and found a couple of older threads where there was some disappointment voiced regarding the finish from the tool.

So I am putting up a thread here for some updated feedback.

1. Anyone using one of these in a knee mill and if so, what's your opinion?
2. For those that may have been disappointed in the past with the finish, have you discovered any magic to make it more acceptable?

I don't own one, but from what i have seen, it look likes it works perfectly fine to me.

Alan, you are welcome to borrow mine if you’d like. I was not happy with the surface finish but you may have different results. Personally, I’d rather have a 3” shell mill, and do.

Thanks David, what shell mill do you have? I have been looking at integral shank Glacern face mills.

Alan, I bought two different ones on eBay about 15 years ago, so they are not current production. That said, I have this 3" diameter Kennametal unit with very pointy inserts (now only available periodically on eBay) that I use exclusively for Aluminum.

And this 4" Sandvik that I use exclusively for Steel and SS":



My complaint about the SuperFly is that it's difficult to dial in the feeds/speeds such that the cutting tool doesn't develop a harmonic and translate that into the finish quality. I do not have that kind of problem with either of the shell/face mills shown above - they are both pretty tolerant of wide varions of speeds/feeds since they are so massive and robust and don't develop harmonics easily.

If you were running a CNC mill, where you had the formula down and part of the tool library parameters for the SuperFly, you can probably get good results from it consistently - I know John Saunders has, and he loves the SuperFly. I suspect he would think differently about it were he to take it to his Bridgeport. Also, the tool holder that's in the SuperFly is pretty small section (I'm guessing 8x8mm) and that has to contribute to the temperamental nature of the harmonics it develops at the wrong feeds/speeds.

My offer stands if you want to try it, I can post it to you including the cutter and a TSS adapter for R8 if you want to give it a try. If you like it, I'll make you a super deal on the package.

Hope this helps.

Alan H said:

For those that may have been disappointed in the past with the finish, have you discovered any magic to make it more acceptable?

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Alan, the Superfly is actually a good flycutter. I've used it enough now that I think I've sorted it out, sort of.

The issue with the finish, in my opinion, is that the insert contacts the material with a broad contact point. The nose radius is flat and quite broad. This large contact area produces a large radial cutting force that pushes the cutter away from the surface. As a result, the tool flexes/vibrates and produces a less than ideal surface. Don't get me wrong; it is flat and it does reflect but if you look carefully you will see tiny ridges in the work that may not be palpable but are visible.

As we know, one way to reduce cutting forces in general is to increase cutting speed and this actually does help reduce the ridge effect significantly but it doesn't eliminate it. If radial forces are the culprit then taking bigger depths of cut should help and it does; going at least 0.0100" deep allows the tool to cut much better and you get less vibration. Going deeper takes off more stock but it doesn't change the finish, at least in my shop.

The other force that is present but not controllable without some kind of balance beam are centripetal forces, just like with a boring head. This complicates things because while increasing cutting speed reduces cutting forces, it also increases centripetal force. Since we know that increasing the radius of the cutter actually reduces centripetal force, I tried using the cutter at max extension and this does seem to help the surface finish.

So, max extension, higher cutting speed (optimal for me is about 2400 rpm in aluminum) and at least a 0.0100" depth of cut seems to produce a decent finish. I also found A-9 cutting fluid to work better than WD-40 with aluminum but that is already an almost universal experience. The resulting finish is quite acceptable and dead flat. It is possible to beat the finish with a single-insert face mill (much more rigid and you can choose a larger nose radius). I haven't used a HSS tool in a fly cutter in a long time but as I recall, this will also give a better finish but you will not be hogging material like the Superfly can. That thing is a beast and will throw chips across the shop!

Overall, I think it is a good tool but it is not a finishing tool. It will make stuff flat and produce a smooth surface but machining marks will show. Are these marks objectionable? Dunno' - how long is a piece of string? That NYCNC guy seems to love his Superfly and my tool leaves fewer marks than his does so eye of the beholder, right?

You also might want to look at the B-52 flycutter and the Suburban Tools flycutter. Both designs minimize centripetal forces ... at a cost.

Thanks David for the detailed response and the kind offer. Your point on harmonics is very interesting and is consistent with some finish issues I read about elsewhere.

Thanks Mikey for your detailed and thoughtful response. A lot to digest and it seems to support David's observations. I have seen the B52 but the downside of it is the cost premium it carries.

So my big take away is that neither of you see the Superfly as a finishing tool. It was my fear of that deficit you point out that caused me to start this thread in the first place. I have an old school fly cutter that uses a HSS cutter and I use it. So I may be better served looking into the face/shell mill approach before I put any money into another fly cutter.

Thanks again gents for taking the time for such detailed responses.

Alan H said:

So I may be better served looking into the face/shell mill approach before I put any money into another fly cutter.

Click to expand...

If you want a finishing tool, pick up a left handed turning tool like this to use in your fly cutter. I've used this set-up many times, and it always leaves a good finish.

http://www.shars.com/3-8-lh-sclc-small-screw-lock-positive-insert-tool-holder

Alan H said:

So my big take away is that neither of you see the Superfly as a finishing tool. It was my fear of that deficit you point out that caused me to start this thread in the first place. I have an old school fly cutter that uses a HSS cutter and I use it. So I may be better served looking into the face/shell mill approach before I put any money into another fly cutter.

Click to expand...

I think your expectations need to be realistic. No cutting tool I know of will produce a finish that I would call a "fine" finish. You need a surface grinder for that or you need to put some time in with some finishing material like sandpaper, buffing compound, etc. A fly cutter, end mill, face mill, shell mill will all leave machining marks; they may be very fine and hard to see but they are there, so if you want a super-nice finish then a cutting tool ain't gonna' do it.

The advantages of the Superfly are that it cuts a 3" wide swath and is simple to use. As fly cutters go, it ain't bad, Alan. I think those circular cutters with one or two inserts will work better, as will a face mill with a single cutter, so it is a matter of practicality and cost. The Superfly is relatively cheap and does the job.

I will match David. If you want to try mine, I'll box it up with a few inserts and the TTS collet and you can try it and decide if it meets your needs.

Thanks Mikey, I couldn't agree with you more that I need a surface grinder and I do study them from time to time!

But back to Superfly - does one need the TTS collet? Tormach says their TTS collet is a "R8 collet with modified length allows for mounting all TTS tool holders in R8 taper spindles". My assumption that a 3/4" R8 collet would work well may be false. By the way, my assumption was driven by Little Machine Shop's claim that a 3/4" collet will work but I am now wondering if that is optimum?? Does the flat face on the TTS collet allow the Superfly to butt up to the collet face and assure the maximum insertion of the shank?

Thanks for the kind offer to loan me your Superfly. I only borrow tools from people I don't like! Seriously, I do not ever borrow tools if I can avoid it but your and David's offer are very generous.