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.

Reply to
Existential Angst
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I didn't really understand what you said mostly, but if your facing tubing and you are bearly holding it down, take some light passes in z thru the thickness of the tubing wall, then take big passes till you reach the bottom tubing wall, then small passes again. As far as finish passes, just take one, feed slower. Am I even close to what you were talking about? lol

Reply to
vinny

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.

Reply to
J. Nielsen

Dude, you nailed it -- I think... :) I'm coming down in Z through the *vertical* wall, so when I go horizontally, I don't hit a "thick wall". Glad yer still here -- occasionally, eh?

Reply to
Existential Angst

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

Reply to
Existential Angst

I'd probably use a roughing endmill and conventional cut leaving .005 and then change tools and finish by climp cutting with a fairly large diameter std cutter.

Otherwise, tilting the work is also great...personally I would use a pair of vise jaws with VEE milled into them as I already have several sets kicking around from side drilling, slotting etc jobs in round work.

Reply to
PrecisionmachinisT

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