While I wait to see if the pieces for the table top are
stable I will go back and work on the arm rails.
Because the table will be disassembled for delivery I
wanted to make sure the four arm rail pieces go back together just the way they
are now. To that end I decided to use
pocket hole screws to lock the pieces together.
However, before I do that I need to route the inside and bottom edges
for two reasons. First, I will not have
to blend the inside face routed edges by hand.
I had enough of that when doing the legs. Second if I waited until the arm rail was
installed the outside bottom edge would be really awkward to get to. Here is my prototype, note the different
radiuses of the round overs.
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| Arm Rail Test |
Process for routing is to clamp a piece face down then
route the inside bottom round over with a 1/8” radius bit then the bottom
outside edge with a 3/16” radius bit.
With the bottom done I flip the piece over and route a 3/16” radius
round over on the top inside edge. This
leaves just one edge and the corners to do after the rail is installed. More on that when I get there.
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| 3 of 4 Round Over's Done |
After completing the routing I can start working on
drilling the three pocket holes at each miter joint. Going back to my prototype I slightly changed
the location of a couple of the holes for more equal spacing or to move the
pocket hole a little farther from the edge then transferred the locations to
each piece.
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| Marking Pocket Hole Locations |
With the locations marked I can start drilling. Only problem is the holes are at a right
angle to the 45 degree miter joint which means that when I put the rail in the
jig it is at a 45 degree angle and the jig’s clamp will not hold the rail in
place. To fix I clamped a few scraps
together to make a brace that holds the arm in the right place. The catch is I have to adjust the brace for
each screw location. Not hard, just
little time consuming.
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| Jig Set-up for Drilling Pocket Holes |
After I drilled the first hole I decided to add a stop to
help in uniformity.
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| Stop Added to Set Up |
Once all the screw holes done I can start assembling the
pieces. I have found the only real
problem in using pocket screws is keeping the pieces aligned when screwing them
together. Because the screws go in at an
angle if both pieces are not securely clamped in place or if there is a gap
between them you can end up with a slight misalignment. Usually it’s a slight upward shift of the
second piece. Now I am after a dead
flush miter joint here and a shift would cause me some real grief. Kreg has a flat plate vice-grip style clamp
that does pretty good but in this case I want to make darn sure nothing
moves.
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| Kreg Clamp |
It’s time to go a lot heavier duty and use some old
fashion malleable iron C-clamps. With
them I can apply enough torque that the oak will cry for mercy and won’t dare
move. Since I am really going to apply a
lot of pressure and don’t want the wood dented from rough spots on the clamping
faces so I checked them for smoothness and found a couple of bad spots. A little work with a file and they were nice
and smooth.
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| Smoothed C Clamp Faces |
Now I could set the arm rails up on blocks put on the
clamps and run the screws in. With the
first joint done I worked my way around clamping and installing screws. When I got to the last joint I was pleasantly
surprised in that it was less than 1/16” off of perfect alignment. That certainly exceeded my expectations.
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| Installing Screws |
With all the joints securely screwed together I flipped
the assembly over and moved it into place on the table. Here is how it looks, I think it defines the
perimeter of the table and ties it all together but then I am biased.
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| Arm Rail Set In-Place |
Taking a closer look, I am quite happy on how tight and
flush all the joints are. This is
typical of the fit. If you look close at
the bottom horizontal piece right at the joint you can see it is chipped. That chip has been there all along and is not
a problem because when I route a round over of that edge it will disappear.
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| Perimeter Edge to be Routed |
Next is to attach the arm rail assembly to the
table. This is done by installing a
screw up through the spacer into the arm rail.
There are quite a few screws already in the spacer. To make sure I did not have a conflict I
needed to make sure I knew where those screws were. Some I could see and on some I had what I
thought were layout lines but was not for sure.
To verify I took a rare-earth magnet set it on the spacer close to the
layout line. Sure enough the magnet was
strong enough to pull itself over and be centered on the screw which just
matched up with the layout lines. Based
on that I located where my pilot holes go.
They are marked in green to help me keep things straight. All I needed to do now is to drill 24 holes.
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| Locating Screws with Rare Earth Magnet |
With the pilot holes done I centered the arm rest
assembly on the table and clamped it there.
With the clamps holding it in place I got on my back crawled under the
table and drove the screws in. I should
mention that the spacer is almost 13/16” thick and the arm rail is slightly
over ¾” thick which together totals almost 1 9/16”. The screws are 1 ½” long the difference being
a shade under 1/16”. I probably would
have been alright to just drive them in but that’s cutting it a little close so
I added a 1/32” thick washer for peace of mind.
Here is the view from under the table looking up at the screw going
through the spacer.
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| Screws Holding Arm Rail In-Place |
Next Up – Routing the Top Rail & Starting on the Top
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