Frank Lloyd Wright Desk Lamp - #7 Completing the Base

The maple plywood top that will cover the base comes next.  In the design phase I had two ways of installing the top.  Cutting a rabbit into the sides so the top is flush with the rail or cutting a groove in the side rail so the top is recessed down.  The drawing below shows the two options.  The method on the right is the easiest to do.  If the base is a little out of square then the error is hidden in the groove.  The bad news it would have reduced the size of the column supports.  I could have made the base thicker to compensate but wanted it to be as thin as possible.  That left me with the method on the left.  I could get the thickest column support pieces with the minimum base thickness.  However, because the top butts right up next to the rabbit in the side rails the rabbit has to be cut perfectly straight and the top has to fit the opening exactly.

Earlier on when I the checked glued-up base side rails my diagonal measurements looked just about perfect.  In this case as I was working on cutting the plywood top to fit “just about perfect” turned out to be three hundredths of an inch off.  My fix is to use three playing cards as a spacer between the fence and the top.  Below shows the table saw setup.  The cards push the top away from the fence and I get a straight taper from three hundredths of an inch to zero.

With that cut and using a hand plane to add a little bit of back bevel on the edges the top fit in just right.

The last bit of work on the base top is to cut the hole for the column.  With the top cut to size all I have to do is set the column support pieces in place and mark the opening.   The column has a small (3/32”) lip that will set on the top when the column is installed.  This is what the lip looks like with the column upside down.

I was a little concerned when it came time to actually cut the hole that the thin veneer on the exposed face might splinter.  There is that lip which will cover up some splintering but 3/32” in not very much.  To help minimize that possibility I used blue painters tape to cover the cut lines on the face and reversed the blade in the coping saw so it cut on the pull stroke.  This is what it looked like from the back when I finished cutting and from the front after I removed one of the pieces of tape to see how the edge looked.  Pretty good I think.

It’s now time to do a test fit with all the pieces that go together to make up the column and base and this is how it looks.  The column sits down tight to the plywood which fits tight in the base frame.  I am happy with it so far.

Now that all the parts fit checks out next is to take everything apart and start screwing it together using the pocket screws.  I start by setting the top of the column support flush with the bottom of the rabbit for the plywood top.  After that I clamp it tightly in place then flip the base over so I can install the pocket screws.  Here is what that looks like.  The clamp is to make darn sure that noting moves and stays just where I want it.

With the column support securely screwed in place I put the column in my bench vice then put the plywood base top in and finally put the dry fit base onto the column.  The column gets screwed to the base with 4 screws, three pocket and one straight in.  Process for the three sides with pocket screws is to make sure column is square to base then run the pocket screws in place.   The 4th side does not have a pocket screw but is installed straight in via a counter sunk hole.  Because of the tight space I had to mount the screw driver in a ratchet socket wrench.  It makes more sense when you look at the photo which has the three pocket screws already in place.

The way the column support assembly is built I will have about 5½” of width that will be subject to change in width due to humidity variations.  Not so much here in New Mexico but other places yes. Not taking the potential for expansion is critical.  When wood expands and if nothing has been done

to take that into account something is going to give.  Most likely in this piece it would be the corners of the base or between the plywood top and the base perimeter.  Either would make me very unhappy.  To get an accurate idea of the potential change I use an on-line calculator.  Here is the link: http://owic.oregonstate.edu/wood-shrinkswell-estimator  It says is that in a humid climate in a house with air-conditioning and forced air heating a 5.5” wide piece flat sawn hard maple will experience a width change between summer and winter of about .1”.

Now that I know how much movement I need to allow for I am going to trim off a little from each end of the last spacer and leave an expansion gap between it and the glued-up column support assembly.  This is what the end result looks like.

For now, this finishes the work that needs to be done on the base.  I still have to do the finish sanding and route a slight radius or add a 45-degree break to the sharp edges.  I have not decided which one yet although I am leaning toward the 45-degree edge since there are not any curves on the piece.

Next Up – Spacers & Starting the Boxes