[How do I?] Create A Bellmouth For A Slide Handle

[Flightmap]

i am making Harold Hall's lining tool. I need to make his bellmouth hole for the slide handle. It is an ellipse (top and bottom, with a circle in the center). I think of it as two trunkated elliptical cones stacked top to top. I thought of turning my milling head equally side to side, but I loose the center of the circle (which is in the center of the shaft) making the "fulcrum" area out of round.

Looking for ideas that solve the problem

Ken

 

[Bob Korves]

Well, whatever you do the center of the pivot must be in the middle of the hole and at the correct height...

 

[omni_dilletante]

It is hard for me to follow what you are trying to do. I found this picture if the lining tool:



I think you are working on the slot that holds the pivot for the handle.

I would be tempted to drill the center hole, then tilt the work piece in the vise and mill each side. Keep in mind that the with of the slot should provide a good fit for the handle, but the ends just need to provide clearance as the handle pivots.

Don't make it any more difficult than you have to. That is advice I need 95% of the time, I wish I would listen to it.

 

[chips&more]

If you rotate the part about its center with an end mill cutter going completely through. Then you will have a circle in the center with elongated holes. But, I ask? Do you really need that? You could just mill a slot? Couldn’t you?