Facing tubing

Awl --
Here's a technique I'm implementing, for your comment.
I'm facing 2x2x1/8 alum tube, about 48" long, so of course it's being held
along X, but not super-rigidly, due to the nature of the fixture -- a kind of diy pallet plate ditty, with no real "stop" along X, just 1/4-20 screws+washers holding the material down in Z. On a fadal 30x16
So facing the ends (em moving in Y) will occasionally present a large milling load, when coming to a vertical wall, as the em moves along Y. iow, for about 1/8", the em will think it's facing solid 2" material.
My solution to this transient load is to first mill out these vertical sections by bringing the em down in Z at the center of these vertical walls, effectively milling out the bulk of the material that would be faced.
NOW, when I face along Y, the transient loads are much lower (judging from chatter), and the em "thinks" it's mostly facing just two 1/8 horizontal walls (top and bottom).
So now, hopefully, I can worry less about movement along X, AND get a more uniform facing.
There are actually 4 of these tubes held on a plate, separated by 1/4" hold-down screws, so there will actuallly be 8 plunges. I figger I'll get all the plunges out of the way, and then do one facing pass, proly won't need sep. rough/finish passes.
So if this is a good idear, hopefully y'all can use it; if there are better idears, ahm all ears...
I figger I'm also getting more "use" out of the em, sharing the cutting load between the bottom and sides.
--
EA



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On Sat, 21 May 2011 11:03:10 -0400, "Existential Angst"

I would probably try turning the parts 45 degrees in the fixture to make the cuts diagonal to the square profile. You'd need a 3" long end mill or thereabout, but the load will be evenly distributed over the length of the mill.
Of course the fixture will need some rather deep 90 degree angled cuts to keep the parts from rotating - Perhaps a profiled top clamp as well. As a bonus, the parts will flex slightly when clamped diagonally and even out the load.
--

-JN-

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wrote:

Inneresting idea -- mebbe not practical for me, but inneresting. Resembles cutting angle iron in a band saw.
--
EA


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