need to make exact concave radius to dish a cylinder ( piece of 1" mdf to be milled into dish surface)

[dparham_is]

Hi, I need to make exact concave radius to dish a cylinder ( piece of 1" mdf to be milled into dish surface) 

i tried what little I know as it semed to work on other things is extrude the part to the shape and let it cut the extrusion to that chat, in this instance I tried a large ball with radius i needed but when i do this and delete ball the flat surface of the cylinder was back to flat.. nothing cut as i merged them... the other way was using offset plan and point sketch but i have no way of knowing what my ending radius is more than just eyeballing... i need a 20ft radius and will use that convex surface to dish out a 30" x .75 flat surface and I few other rdaiuses 

[seth.madore]

Could you share your file so we have a better sense of what you're dealing with?

File > Export > Save to local folder, return to thread and attach the .f3d file in your reply

[JDMather]

Revolve.

[dparham_is]

how would I calculate the exact dish concave? all I know is the radius would be 20 ft and one for 298ft

[dparham_is]

IM checking this out now! thanks!