The flat bottom isn't a concern, the mortises are to receive 1/2" square metal spindles (hollow) and the ring
that is left after
drilling the mortise prevents the spindle from being fully inserted. (This a stair rail project)

The shoe (bottom rail) thickness is only 5/8" so I don't have a lot of room to play with.

The ring that is the problem would also prevent the 1/2" slugs from being pounded to the required depth.

The general consensus here is that the mortises are correct and while time consuming, chiseling out the
offending ring
seems to be the solution.

Thanks for your response,

David.

"SonomaProducts.com" wrote in message
oups.com...
One more (maybe crazy) idea.

If you really need a flat bottom, then drill the mortise 3/8" extra
deep. Mill some stock to 1/2" square. Cut 3/8 wafers and pound them
into the mortise with a dao o glue underneath.

On Mar 17, 9:55 am, "David" cosmosatnointerbaunspamdotcom wrote:
Thank you all for your responses.

I have never used a mortise machine before and didn't know what to exprect.

I'll be using a sharp chisel to clean the ring out of each mortise.

David.