Router Plane

Monday, August 21, 2017

Frank Lloyd Wright Desk Lamp - #3 Baffles, Center Column & Boxes

After letting the column set overnight I decided to check and see how they matched up.  Although both had a bit of a bow in them I thought that when I clamped them up with the bows opposing each other they would cancel out.  At least that’s the idea.  To test I pulled out an armload of clamps and set to work. 


The first clamp I pulled out was one that had a rough face.  If I torque the clamp down all those bumps will dent the maple surface which I don’t really want to happen.  The fix is simple, take some time to put it in the vice and file the face smooth.  Here are before and after shots.


With the clamp faces cleaned up I did a test run and everything came out fine.  That said I will let the two halves set for a bit longer to make sure they are stable.


Next, I checked the pieces that will make up the baffles.   Almost all of them were still flat but a couple had developed a bit of a cup.  Not much maybe a thirty-second of an inch.  I think they are stable but will wait to glue them up for a couple more days.  I did run the edges to be glued up through the saw to clean and square them up.  There is a method I use to cancel out any error in case the saw blade is not exactly square with the saw table.

In the photo below the angled pencil line shows an exaggerated example of what the edges would be if the saw blade was way out of square and I made the cut with the top of both boards facing up.  Later, when I did the glue-up I would not have a flat piece but would get a “V” shape when the outside corners pitch up to make the edge joint close.


The fix is to run the “A1” piece through the saw with the top face up and piece “A2” through with the top face down.  Doing that gives me cuts like the pencil lines below.  Then when glued up the error is cancelled out and I get a nice flat plane across both boards.

The test clamp confirmed the piece was flat and because the pieces went back together the same way they were cut apart the joint is all but invisible.

In the drawing for the boxes I had shown just a miter as the corner joint.  Glued miter joints are not all that strong because they are mostly an end grain joint.  While the light should not be subjected to a lot of banging around I really wanted something to reinforce the joint.  There are several possibilities such as a dovetail joint, mechanical fasteners like nails or screws, splines and biscuits.   Because I did not want to draw attention to the joint the options were quickly narrowed down to a couple.  First, a countersunk screw where the hole is filled with a face grain plug cut from the same piece of wood and second using a biscuit. 

I decided to made a couple sample pieces for destructive testing.  These photos are of the screwed joint minus the plug and the biscuit reinforced joint prior to assembly.


After letting the glue cure I tried to break the joints by hand and guess I cannot qualify as Hercules as I could not break either one just using my hands.  Putting them in the vice and using it to really load them up got the desired results.  The one with the screw failed as I expected by pulling the screw out of the end grain.  I could have increased the strength by using a bigger longer screw or adding a second one.  The biscuit reinforced joint required quite a bit more force to break.  Looking closely at the break I could see where the biscuit itself had broken leaving small splinters on the slot cut in one of the pieces.  Since the biscuit joint is at least as strong as the screwed one I will use it to make the joints.  The main reason is that once installed they will be completely invisible and for this design that is my goal.


Now that the baffle pieces had set a while longer I did one last clamping dry run.  Three of the sets checked out fine so I glued them up.  However, one pair just did not come together.  The individual pieces had not cupped but when clamped up there was a “V” between the outside edges joint in the center.  To fix I made a bare skim cut on each joint edge with the table saw.  Re-clamping and checking with a straight edge showed a flat surface.  With that done I glued up the final baffle.


After letting the glue joints cure overnight I changed the sanding grit in the thickness sander from 80 to 120 and flattened them.  They are still too thick at 11/32” but being just a little paranoid I am going to let them set for a bit before going to the final thickness.

While they set it is back to the working on the column.  In order for the wiring to be hidden inside the column I need to cut matching dados centered in each half of the column.  Once the halves are glued together I will have my wiring chase.  Below is a drawing showing the highlighted wire chase cuts.  All the milling on the column is shown but except for the chase they will be done later.  Note that, for now, the top cap which will go on the right end, is missing from the column.  That is because I will be running the chase the full length of the piece and I don’t want the top to have a ½” square hole in it.  I could have cut a stopped dado but I think it is easier and safer to make a full length cut versus one that stops a couple of inches from the end.  More details on how the cap will be attached later on.


Next Up – Center Column, Boxes & Baffles

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