Round Tapered Legs made a different way

[jteneyck]

The tapering jig I showed the other day was to prep some legs that I needed to "turn" with a round taper.  I'm a lousy turner, and I knew I would never be able to make perfectly straight tapers, and any deviation would stick out like a sore thumb.  So I decided to use my CNC to do it.  The limited Z axis capacity of my CNC called for machining in a way that didn't give the smoothest finish, but after sanding they look perfect.  

I drilled 3/8" holes in the center of both ends of the legs.  I glued a 3/8" dowel in the foot and threaded a piece of 3/8" all thread in the top.  Those "arbors" are held in a simple jig I made that's mounted parallel with the X-axis of the CNC.  The CNC and me running a hand drill did the rest.  



As you can see, it's pretty rough, but after 60 grit up to 220 grit it looks beautiful.




These legs are for a Lane dining table I'm building.  The design is interesting; the tapered section meets a square section at the top, and the outside corner of it is round over to match the diameter of the taper.  I rounded over that corner with a hand plane.  
 


John

[FrankAtl]

That's thinking outside the box! Did you program the CNC to raise the z-axis at the taper angle as it slowly moved along the x-axis or am I overthinking this?

[jteneyck]

That's thinking outside the box! Did you program the CNC to raise the z-axis at the taper angle as it slowly moved along the x-axis or am I overthinking this?

That would have been my preferred approach, with the bit centered over the workpiece and using a fluting toolpath so the tip of the bit is doing the work, but I don't have enough Z-travel to do that.  I had to machine from the side of the piece, using the side of the bit, and that's why it comes out rough.  Because of the height limitation, there is no Z-axis movement in the toolpath.  The cut is made by using a pocket cut, actually two of them, one roughing (red) and a second one to remove the last 1/8" or so.  This ends up with a lot of time spent cutting air, but it worked.  
 



John

[FrankAtl]

Always more than one way to skin a cat. I use VCarve Pro on my CNC too. Really like it.

[jteneyck]

Always more than one way to skin a cat. I use VCarve Pro on my CNC too. Really like it.

Agreed.  It was worth every penny.  I've been able to do everything I've wanted to with it, limited only by my knowledge of how to use it.  

This weekend I'm going to mill a couple of Telecasters for a friend using some 8/4 walnut I cut a couple of years ago.  Another new experience I never would have undertaken had I not bought the CNC.  

John