Fluting a replacement base for a 18" Greek Doric column for an historic house on West Jefferson Street in Oak Cliff.  This saves 17' of the original column not counting the cost of replacing it.  Note the 3" piece of original column used to get the proper spacing and depth.  The flutes were originally  1.75"  across and .85 deep.  Over the years with wood movement the flutes varied as much as 3/16".  Columns usually rot because of improper installation or because the vents are sealed.  A hollow wood column needs 1 square inch of vent area at both the top and bottom for each inch of diameter.  These columns rotted because someone sealed the top vent.  The router sled is from my Legacy 1500 which will only handle up to 11" diameter so I made this one for my lathe.

The completed base from mahogany.  I measured wrong on this one and had to come back and add 3/4" to the fluted portion.  There are a lot of burn marks from the dull 1 3/4" cove router bit.  There was up to 3/16" difference in the flute widths and the column was 1/4" out of round.  Fairly standard for a 75+ year old column.  Flutes were done 1/16" under size so that once the base was installed and any voids filled with WoodEpox they could be sander down to match the original column.  When the second coat of paint was done you couldn't tell that a repair has been made.  If the vents are not closed off again these bases and original column should last for 100+ years.

Here are some proper column bases that allow for ventilation of the column.  On the left you can see the original base and the new base on the right.  The were from restoration at Ft Sill OK.