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Monday, September 4, 2017

Frank Lloyd Wright Desk Lamp - #5 Fitting Column Cap, Column Dados & Starting the Base

Next is to make the column cap and the tenon that will tie the two together.   The tenon will have a square bottom to fit in the square chase in the column and a round half to fit into the ½” hole in the top. 

I started with the tenon using a piece of scrap oak and cut it to ½” wide by .53” thick.  I had intended to use a ½” square piece but when I measured the center chase it was .03” of an inch over ½” in one dimension.   I must have had the dado blade set to cut just about .015” deep.  One cut in each board equals the .03”.  With the blank done I marked where the square part ends and the round starts then mounted it in the lathe.  To keep the corners of the square part from chipping off while turning the top half round I used a Japanese fine-toothed pull saw to make a small cut on each of the corners.

It did not take long to turn the square round, measure and fit it to snugly fit in a ½” hole.


The column cap is easy.  The only thing I had to keep in mind when cutting the 2” long cap from the end of my 14” blank is to make sure the grain matched up with the end of the column.  Once cut I marked the center, put it in a wooden hand screw clamp and drilled the hole.


Here are is the long column on the left, the tenon in the center and the cap on the right.  Later the top of the long column will get a ¼” deep reveal cut on all four sides.


Assembling the three pieces and clamping them together shows how the grain flows between the column and the cap.

Laying out all the dados and holes in the column are next.  No two sides have the same arrangement of dados for the baffles and lights.  It is critical to get the layout right.  Either that or I do a redesign should I goof up.

Below is the top half of the column with the light and baffle locations marked out.  The areas with the “X” are where I will cut.  However, before I started to do the actual cutting I marked the faces I will see when making the cut either “Yes” or “No”.  If “Yes” it is set up right and if “No” then it’s not.  The reason it can look wrong is you are looking at the top but making the cut on the bottom so it is the opposite face from what I see that actually gets cut.  Seeing the cut lines on the up face is a powerful visual que that it is OK to make the cut when it may not be.  I know it sounds simple but believe me from experience it’s really easy to do it wrong.

Here is the table saw setup.  The board clamped to the crosscut fence provides backup to the cut so when the blade exits the edges of the piece are not chipped.  The piece of oak clamped to the rip fence is my stop.  Before each cut I push the column up to it for a consistently located cut and clamp it in place with the tall wood clamp on the miter gauge.  I use the tall clamp to make sure the column does not move during the cut.  That would be a bad thing.

After making all the cuts for the baffles I added chippers to the dado to get a 13/16” wide cut for the top of the column.  The final cut is only ¾” wide but I wanted it a little bit over size to eliminate one of the score marks the outside blades leaves.  The outside blades cut a score line at the outside edges that are just a tiny bit deeper than the rest of the dado cut.  That is also why I did not make multiple passes with the 5/16” stack I used to cut the baffle dados.  I need a flat smooth bottom here as it will be exposed.  Here is what the column looks with all the cuts done.

Next, I checked the fit of the cap on the column and made some minor adjustments then sanded the dado and end grain cuts smooth.  Here is what the cap looks like on the column.

Setting the column aside for a bit I worked on the base.  There are quite a few parts to the base, most of them hidden supports to provide the necessary strength for the column and it’s attached parts.  The base is only 1 7/16” deep and the column sets 40” plus above the base.  That sets the stage for a lot of leverage where they come together.   To make sure the column won’t break its connection to the base I need to make it pretty stout.


After getting the perimeter pieces for the base to final thickness and width I cut them a couple inches long mitered the ends and did a test fit to check and make sure the miters fit tight and square.  With everything checking out I set up a stop block on the miter fence and cut the pieces to their final length plus 1/8”. 


Next is to cut the rabbit that the maple plywood top will fit into.  First is to set the width of the cut, in this case about 3/8” and a little deeper than the thickness of the plywood.  That is so when I make the next cut I won’t have to match the corner exactly.  There is another reason that I will go into when it’s time to glue the top on.


Second is to lay the piece face down, set the width of the cut to just over the thickness of the ¼” plywood.  I want it a little thicker so I can use a scraper to bring the top of this piece down to match the plywood exactly.  Plywood is not always the same thickness so I want a little buffer to work with.  I can always shave a little off the top of the perimeter pieces but because the veneer on the plywood is only about .025” thick there little to no margin of error there.

I can now cut the pieces to their final length.  Here is the jig I use to cut the miters.  The reason for the extra 1/8” is because when I butt the piece to be cut against the fence then make the cut I lose 1/8” in length.

Here all four finished pieces are in the framing clamp.  No glue here just checking to make sure all the joints are flush, tight and square.



Next Up – The Base Part 2

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