| The building process obviously starts with cutting the
MDF panels. This is done on a standard table saw and I did not see any benefit
to showing that process. But once the panels are cut to rough size...
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Building the Cabinets |
Mike, my trusted
assistant, uses a template to route the rough panels to the exact shape
required for the backs, braces and front baffles.
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A drill press is used
to prepare braces for the removal of excess material.
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A sabre saw is used
to remove excess brace material.
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One the excess
material is removed and the inner edges rounded over, a biscuit joiner is used
to prepare the finished braces for positioning during
glue-up.
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The interior front
baffles are routed for driver cutouts and the back side of the woofer and
midrange cutouts are rounded over.
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Once the interior
baffle is complete, it is glued to another, slightly over-sized piece of 3/4"
MDF. This added piece will be the outer front baffle of the cabinet and will be
trimmed flush with the inner front baffle once the glue has set.
The
outer front baffle driver cut-outs will be made with a pattern router bit after
the cabinet is veneered and finished. The inner front baffle cutouts will be
used to guide the bit and duplicate the holes in the outer front
baffle.
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A biscuit joiner is
used to prepare the side panels for glue-up. This insures that the panels are
easier to position and remain in place during cabinet
glue-up.
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All the panels and
braces are now ready for glue-up.
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We apply glue to one
of the side panels.
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The cabinet bottom,
back, two lower braces and shelf are positioned in place on the side
panel.
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The sandwiched front
baffle is positioned in place, biscuits are inserted and the cabinet is now
ready for the the opposite side panel to be glued in place.
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Once all these panels
are in their final position, it is time to clamp everything
together.
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the next step is to
glue up the top of the cabinet. The top braces are inserted in place first.
Again, biscuits help position and hold the top in place until clamps can be
applied.
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Clamps hold the top
in place until the glue sets. At this point, the cabinet is left to sit until
the glue sets and all the joints glued up so far.
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Looking at the top
section of the cabinet prior to gluing up the top sides, the shelf seams are
caulked to insure a tight seal.
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The top side panels
are then glued in place and clamped. Because the top sides are tapered, a
different type of clamp is required.
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After the glue has
dried thoroughly, it is time to sand all the joints smooth and begin the
process of preparing the glued-up cabinet for veneering.
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Filler is used to go
over all the joints to make sure they are smooth.
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The filler is sanded
smooth and flush with the panels.
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Finally, since the
end-grain of MDF expands and contracts at a different rate than the face, a
sealer is used to seal the end-grain and diminish any potential telegraphing of
the seam when the cabinet is veneered (or anytime in the future for that
matter).
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Veneering the Cabinets |
Some pieces of veneer
are wide enough to cover an entire speaker panel. But more often than not, it
needs to be spliced to create a piece that is wide enough. Trees only grow so
wide. So, depending on the type of veneer, splicing is often a
necessity.
After the veneer is trimmed with a perfectly straight edge,
the veneer pieces are joined in a mirror-image fashion and taped together on a
temporary basis. This is done on what will be the glue side of the finished
veneer panel.
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The panel is then
flipped over and veneer tape is applied to the "show" face. This perforated
paper veneer tape is very thin and only serves to hold the splice until after
the veneer is applied. It is removed in the final cabinet sanding
process.
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The spliced veneer is
then trimmed to approximately 1" wider than the face of the cabinet it will be
applied to.
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Since the first panel
is for the rear side of the speaker cabinet and the top is tapered, the "kawl"
used when applying the veneer is used as a template to remove excess veneer and
cut the sheet to its final dimensions.
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Finally, the
temporary tape is removed from the glue side of the resulting veneer panel and
it is now ready to be used.
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Veneer glue is
applied to the surface to be veneered.
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The veneer panel is
placed in position and tape is used to make sure it does not slide during
insertion into the veneer press.
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The "kawl" is placed
on top of the veneer. Since the press will exert 2 tons of pressure per square
foot, the veneer needs to be protected around the edges of the cabinet. The
kawl is slightly larger than the face being veneered and protects the veneer
and helps to press it perfectly flat to the cabinet
surface.
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The veneer press is
like a giant plastic bag. The speaker cabinet is inserted into the bag, it is
sealed, and a vacuum is applied to remove all the air. This creates two tons of
pressure per square foot on the surface being veneered, insuring that the
veneer is pressed flat against the cabinet surface.
The cabinet will
remain in the press from 2 - 4 hours depending on the actual glue used in the
process. Once the glue sets, the cabinet can be removed from the press and the
glue will continue to dry.
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When the cabinet is
removed from the press, the kawl and tape are removed, revealing a completely
flat veneer surface.
As you can see, the veneer extends beyond the edge
of the cabinet and the kawl protected this edge while the cabinet was in the
press.
This excess material will be trimmed flush with the edge of the
cabinet before the next side of the cabinet is veneered. This is done with a
router and a flush trim bit. The edges are then sanded flush with the cabinet
edges.
This process is repeated for the eight cabinet sides and two
cabinet tops in a pair of HT3's.
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The cabinets are then
sanded in preparation for finishing.
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The front edges are
routed, revealing the trim that was originally glued to the panel
edges.
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Finishing the cabinets |
Tim wanted a certain
color. So we spent an afternoon formulating an aniline dye that would result in
the desired speaker color. Here we spray the dye on the
cabinets.
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Here's another shot
of the dye process in progress.
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Here's a
close-up of the curly maple veneer with the custom dye applied. It is starting
to look pretty nice. Next we'll apply multiple coats of gloss
lacquer.
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Well, despite our best intentions, we never
shot the remaining pictures (I wish we had).
But the steps were failrly
straight forward. We shot many coats of lacquer and waited until it cured. We
then rubbed it out to a high-gloss piano finish. The results are shown in the
photo at the top of this page.
I guess there would not have been that
many additional photos after all.
As for the results, Tim emailed me
upon recieving the speakers, "Thank you, for making my dream of "The Perfect
Pair of Speakers" come true. "
You're very welcome Tim! |
