Single tool boring heads can be used for for outside turning (you need a reversed boring bar, no big thing) Standard boring heads for mills are sometimes two headed - usually for speed I think?
I would think you could get the right effect with either (a) a single point tool being programmed in a kind of in/out breathing helix or (b) a form tool run around in something that looks like interpolating a bore but reversed.
It's not clear to me that you need more than one insert....
Definitely don't need more than one form insert to do this. I drew 2 because that's what the tool I saw looked like, but 1 would suffice.
Why not just a plain ole helical endmill with the form ground into it?
Then it's just like milling a pin or any OD.
Can you mill a .500 radius on the outside corner of a part and get a good finish?
Bob
I can, and I would. The part I need to make has a relatively large OD (3.5") and I'm not positive that the idea I have with the tool I'm looking for will work well enough (don't want chatter). Problem is that there is a feature that sticks out about .400" on the profile of this part with a cut length of 1", so I need a relatively large tool (a 1.5" diameter endmill would only be .700 in the middle). Added to that is I need this tool sooner rather than later, and I would probably be looking at grinding whatever tool I use myself. It'd be a ton easier to grind a piece of flat HSS than it would a big endmill. I may split up the profile into 2 separate tools if I do go the round-tool route.
Once upon a time, this would have been called "planetary milling" and, if a helical path were involved, perhaps "thread whirling". Was a pretty standard technique for shops doing mass production of parts with external profiles.
Yeah, this is pretty much just like thread whirling, but it isn't advancing in a helical motion. I appreciate that there's a term for it. There's not much to go on with a google search, "planetary milling" apparently is a good way to make balls and grind grit down to a uniform size. I did, however, find an excerpt from a book from the 1960s talking about planetary milling, or "planamilling". The latter term doesn't drum up much more results on google.
I might have seen that video. Was it a very large WFL machine doing what appears to be a front landing strut? It looked exactly like the tool you drew and how you described it.
Also pieces of that video are in like a thousand YouTube videos of cool machining so it would be really easy to run across and very difficult to find again.
I don't recall if it was in a "cool machining" video or not, I had youtube on in another tab, and when I came back to the tab, I saw the video I mentioned. It was machining a brass manifold casting that had several male threaded features with grooves/contours on them. If I recall there was at least 2 tools in the video like I drew above. They were threadmilled afterward.
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If I do go try doing this, I have a big Devleig boring head that has a slide that I can remove, put in a longer one that has an L-shape, with a slot to hold an insert towards the ID rather than the OD. It would be a single insert, not 2. I am leaning towards not doing it this way but I've got a couple days to decide. Haven't even finished fixturing this part yet.
