While I was waiting to get the sample pad and playing
surface I started working on the next two sets of parts. The Alignment Guide and the Spacer. If you remember in post #9 this same
rendering had the Alignment Guide shown as Plywood Alignment Guide. Between then and now I decided to change the
material from plywood to oak and increase the thickness from ¼” to about
3/8”. This piece really serves two
functions. First is to keep the
structural support in line with the inner rail and second more importantly is
to increase the stiffness of the inner rail/structural support assembly.
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| Section of Table Top |
The Spacers are pretty easy to do. I took some of the oak leftovers and cut them
just slightly wider than needed then set aside.
The Alignment Guides take a little more time. First using a piece of oak that was not good
enough looking to be used where it could be seen I ripped it into pieces 2 ¾”
wide. These pieces are 13/16” thick so I
could use the bandsaw to rip each board in half widthwise then run them though
the thickness sander ending up with finished pieces just under 3/8” thick.
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| Roughed out Alignment Guides & Spacers |
You never know when cutting narrow pieces like the
spacers from a wide board or in half if there are internal stresses that when
released will cause the wood to move in all different ways. That’s why they are set resting overnight so
air can circulate around them to see what if anything happens. After resting overnight all the pieces looks good. First I cut the spacers to length. This was easy as the length is not
critical. Cutting to width required a
little more precision. For all the
pieces associated with the playing surface to be locked into place the spacers
need to be right on. I started by
cutting them about 1/64” too wide then using the thickness sander to took them
down a smidge at a time. A few passes
later I achieved the friction fit I was after.
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| Fitted Spacer |
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| Playing Pad/Surface & Punch |
Unfortunately, the punch was so dull it was like beating
a hole in the pad with a stick rather than cleanly cutting one. It needed sharpening badly. Using the grinder, I clamped a temporary
fence on the table and ground a new edge.
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| Grinding a New Edge on Punch |
Finishing touch is to use a small half circle diamond
hone to clean up the burr on the inside of the punch.
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| Diamond Hone & Punch |
After trying several different heights of the spacer
screws I settled a 3/16” gap. This
height seems to give me enough clamping force on the pad and playing surface to
hold it in place but not so much as to deform the surface. It is a little higher than the 1/8” I had
originally estimated but then that’s why you do testing.
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| Finished Mockup with Palying Pad/Surface |
Next was to start on drilling all the holes in the spacer
and inner rail needed to tie these pieces together. Here is where the first group goes. They are pocket holes in the spacer and
relief holes in the inner rail.
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| Pocket Holes |
I need a relief hole in the inner rail pieces because a
full-length pocket hole looks like the one in the photo below on the left. The center image is what I have when I drill
a pocket hole in the spacer and the one on the right has the relief hole in the
inner rail. Without the relief hole the
inner rail blocks the partial pocket hole and I can’t get the screw in.
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| Normal Pocket Hole & 2-piece Assembly Used |
With testing done I could start drilling the holes in the
actual pieces. First is to layout all
the hole locations then drill the partial pocket holes in the rail.
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| Drilling Pocket Holes |
Next I set up the fence and depth limiter on the drill
press so I can drill the relief holes in the inner rails.
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| Drilling Relief Hole |
Last is using a Dremel tool with a small drum sander
grind a small cone shaped angled relief notch in the inner rail. This little notch will give me just enough
clearance to get the screw driver aligned with the screw so I can install it.
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| Dremel & Angled Notch |
The work I just did allows me to attach the spacer to the
outer rail but I need to fasten the spacer to the inner rail. That requires more screws and holes
drilled. Since the screws are not long
enough to go through the spacer and into the inner rail I started by using the
drill press to drill a counter-sink. It
is set up basically the same way as when I drilled the relief holes above. Once the counter-sink was drilled I needed to
drill the clearance hole though the spacer so changed to a smaller bit in the
drill press and added those holes. Here
is what the pilot hole looked like at this point.
Next is to clamp the spacer with the counter-sunk holes
up onto the inner rail and line the two up.
When aligned, I could use the stepped drill bit in the silver drill to
mark the location of the pilot hole in the inner rail. The larger diameter at the top of the bit
matches the diameter of the counter sink and assures that the pilot hole in the
inner rail is concentric to the hole in the spacer. However, that bit is not long enough to give
me a full depth pilot hole so I switched to a longer bit in the yellow drill
closest to the silver drill and finished drilling the pilot hole. All this work gives me the counter-sunk pilot
hole as shown on the right. Now using
the yellow driver at the top I can run the #6 x 1½” screws in. One thing that might not be clear in the
photo is when I align the spacer to the rail it is recessed about 1/64”. That is so when I attach the arm rail it will
be pulled tight to the top of the inner and outer rail. More on that later when I get there.
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| Assembling Spacer & Inner Rail Assembly |
Here is what it looks like when installing the screws in
the completed assembly through the spacer into the outer rail. Note how I have just enough room for the
screw driver to align with the center axis of the screw.
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| Installing Spacer & Inner Rail Assembly |
Next Up – Fitting Alignment Guides & Building Miter Jig for Top Arm Rail
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