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Does anyone use a lap grinder with center feed water to grind/polish the edge of a piece larger than the radius of the disc? For example, a 10" bowl on a 12" disc.

Are there risks, issues or problems with this approach? (I'm aware of the hand lapping with loose grit option.)

Thanks

lbailey wrote:Does anyone use a lap grinder with center feed water to grind/polish the edge of a piece larger than the radius of the disc? For example, a 10" bowl on a 12" disc.

yes, all the time.

Are there risks, issues or problems with this approach? (I'm aware of the hand lapping with loose grit option.)

no

Thanks

you're welcome

Thanks Marty, this helps a lot.

Works great for rounds, since at any one time, not very much of the edge is actually touching the disk.

You'll mar your edges trying to do flat edges larger than the diamond disk, however.

Dana W.

Dana- You'd be surprised at the area that you're working on the disk. For a ½ " thick bowl with an outside diameter of 10" and an inside one of 9" (nominally), to get that flat lip you're grinding more than 15 square inches of glass.

15" of glass is not touching the disk at any one time, right? If so, your glass is a lot more fluid/flexible than mine .

I know with my bowls, I can easily work the edge of a 12" bowl on my 8" lap grinder.

Dana

If you're talking about rounding the edge of a disk or bowl by rotating it perpendicularly to the pad then yes, the surface contact is minimal and you could indeed do a very large piece on a very small diamond pad. If you're trying to get a flat rim on a bowl by pressing it open side down on the pad (which is what I assumed the original question was about) then my figures stand.

Yes, that occurred to me this morning as I was thinking about the exchange. I took the original question to mean working the edges of the disk perpendicular to the wheel. Not flat.

It's my paradigm

Dana W.

Marty is correct, I was asking about putting a flat edge on a vessel, edge to be parallel with the bottom (and the ground).

Dana, I understand your point about using the lap grinder to soften the outside hard edge. I've just recently started using that method, saves a lot of time.

Thanks to both of you guys