Polish a casting

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Today I got to try out my theory about polishing a rough cast bell with an angle grinder. If the rough casting was polished as is, there would be irregularities that would show. That would also takea long time. The angle grinder makes the surface flat so that polishing is easy.

Here's the rough casting:


I cut the head off a bolt and screwed it through the bell and put the smooth part of the bolt into a large drill press. Someone's moved the collet chucks so I can't find them. So I used the three jaw chuck at about 120 rpm. Since I was applying almost no pressure with the angle grinder, there's no danger of the bell coming out of the chuck. However a collet chuck would be safer.

I used a flapwheel on the angle grinder and here's the result: Bell2sanded.jpg

A bit of sanding with sandpaper, and then off to the polishing wheel for a superb polish: Bell3polished.jpg

A lot of bells are needed, so we can't muck around polishing for hours!


Brass contains copper, breathing that in is a real safety problem. A suitable mask is needed.

It's unwise to spin such an object fast in a three jaw chuck, because if it comes loose it will fly across the room. The idea is to use the lowest speed of the drill press, as the angle grinder is doing all the work.

See also