Dome Caps

[henry]

I need to cut a dome cap for a post for a remodeling job. I have a 13" x 13" x 2" block of sign foam and I want to mill it where the sides will be 1" and the center will be at 2". I have not mastered 3d in the CAD program yet. Is there a simpler way? I have tried AutoCAD, Vector and my Good Ole Standby TurboCad. I would like for the cap to be in the shape of a dome and not a square point.
Any Help will be greatly appreciated

Henry

[jmw60010@yahoo.com]

Henry,

This should work. I use AutoCAD, but I imagine you could do the same thing in any other CAD package. Generate an arc that meets your size specifications. Rotate that arc so that the plane of the arc is perpendicular to the XY plane. Use the polar array option to duplicate the arc around the center point which will be the top or your dome. The more copies that you create, the smoother your final surface will be. The arcs can then be saved in a dxf format and imported into vector. Generate your NC from these arcs and you should be in business. If this made no sense at all, email me and I could generate the drawing for you and send it your way. I also have a rapid prototype program that will generate toolpaths from a solid model created in AutoCAD. We could also go that route if you prefer.

[rgbrown@itexas.net]

The blue top is keeping the "skirt" a consistant distance.


2640

The Purple top is done similar to Jay's description. I would probably do a "water-line" style cutting pattern with the largest Ball-type bit I had.

Ron Brown rgbrown@itexas.net

[gerald_d]

IMHO, this job is quicker with a freehand sanding machine, for the single cap that Henry mentions above. This is not an ideal application for a ShopBot. It is a "fun" application, but not an efficient "income-earner".

[david@thecarpentershelper.com]

Henry, here is a quick drawn sanding jig for use on a sanding disk the jig is built like a three sided box with the front side going toward the sanding disk hinged at the bottom and an ajustable slide then your foam is placed on that with a nail going through the jig into the bottom side of your foam so you can turn it. sorry no dimentions etc. just size it for what you have. Dave in Wyoming

2641