Right, sand a sphere- how would you finish sand a sphere without causing flat spots? I am sure that there are many methods out there-

Lathe. Blanchard grinder.

Sorry Pat-not enough info given- the "sphere is a half sphere, is made of polyester fiberglass, is 4" in diameter and is bonded to the front and rear(the pressure domes) of my Atlantis sub model. needs to be primed, spot puttied and finish sanded.


Sanding sponge? steel wool?

size? a few ways to use a lathe come to mind,, could you drill it and glue in a stub shaft and chuck it up in a drill?

Originally Posted by patmat2350

Lathe. Blanchard grinder.

A lathe might help, but a Blanchard grinder is used to make flat surfaces

Perhaps make a sanding block that has a concave shape, and line it with some foam under the sand paper?

with the new info you could cut some sanding blocks to match the curves,, would give a little better control..

TGH, good thought-I guess cut sections (like an orange) of sandpaper and contact glue them in place?

What is the diameter of the sphere? Cut a PVC pipe coupler in half to make two tunnels or chutes. Glue sandpaper to the inside.

Originally Posted by pmackenzie

A lathe might help, but a Blanchard grinder is used to make flat surfaces

Right! I was misthinking the process of ball bearing grinding. Here's how it's really done, no application here:
https://science.howstuffworks.com/tr...uestion513.htm

Originally Posted by CG Bob

What is the diameter of the sphere? Cut a PVC pipe coupler in half to make two tunnels or chutes. Glue sandpaper to the inside.

That could work on this...hmm

Might find something useful here: https://www.youtube.com/results?sear...nding+a+sphere

Originally Posted by AirDOGGe

Might find something useful here: https://www.youtube.com/results?sear...nding+a+sphere

Should have done it like this

Explosively hydroforming a steel sphere (0 min 19 sec)

If it's alraedy close, Use the guide coat / wet sanding method to evenly block it out.
The real one isn't perfect either. Welded steel or fiberglass on the original?

DH

Yeah it's welded steel with big gaudy weld seams -hammered, sandblasted and paint... But in 1:24th that all kind of disappears and so it's got to be smooth.

Make a "C" shaped sanding block from soft balsa and spray glue or double sided tape sandpaper to it. You can get a spherical curvature inside of it by putting a strip of sandpaper on your sphere and sanding the shape into the block.