With the screw’s pilot holes drilled in the base plate
they are used to drill the pilot holes in the sliding block. The top photo has the base plate sitting (red
arrow) on the sliding blocks. A board
clamped to the workbench for alignment keeps the edges flush. In the bottom photo you can see both the
holes in the base plate and the alignment block labeled 4B. The underside of the base plate is also
labeled 4B so I can make sure the right piece goes in the right place when they
are glued and screwed together.
Drilling clearance holes in the base plate is next. That’s done so the screw threads don’t bite
into the base plate but only into the sliding block. This assures that the base plate will be
pulled tight to the sliding block. They
are drilled using the same setup and process as the pilot holes but with a
larger diameter bit.
When assembled for a test the base plate and the sliding
block line up as planned. The photo
shows the two screwed together but with a problem. Right now, the screws are slightly proud of
the base plate. That will get fixed by
drilling a small bevel or countersink on each of the holes.
The countersink is made using a bit whose drilling angle
matches the angle of the underneath side of the screw’s head. Here one of the holes has had the countersink
drilled. The previous drilling setup can
be used for only half the holes because all them need to be drilled from the
top side.
With the countersink drilled the pieces can be
reassembled with the screws now flush with the top of the base plate. I probably could have skipped this step but
wanted to make sure the screws were flush before gluing everything up.
Sanding the leveling assembly pieces is next. In general, for a jig like this the materials
don’t need any special treatment.
However, in this case because the leveling assembly will be sliding
along the sled a smooth surface is desired.
I know for sure that the sled will get a lacquer finish to provide a
smooth wearing surface to run against the bottom steel plate in the surfacer. Since it’s not a good idea to finish only one
side of a piece the top of the sled that runs against the leveling assembly
will get finished too. I don’t yet know
if some, none or all the leveling assembly parts will get a finish but it’s
easier to do the sanding before assembly.
Anyway, the first step is to sand the sliding blocks and the base plate
before they get glued together. The
parts are in pretty good shape so only need some work with 120 and 220 grit
paper. Once sanded the base plate and
the slider blocks can be glued and screwed together. To help get a good glue joint the assemblies
are stacked up and put into a couple of clamps.
When I went looking for the thumb screws that will clamp
the leveler assemblies in place a problem came up. As a result of changing the T-nut to an
epoxied in place nut on the sliding blocks the location also moved from
centered to just below center. I didn’t
think it would be a problem but find that the ears on the thumb screw hit the
bottom skin of the sled. Trimming the
bottom skin is not an option as that lip is needed to act as a spacer to keep
the thumb screws from hitting the risers in the planer. I had considered changing the thumb screws to
ones with a wooden knob on the end anyway and now will need to. This is what the sliding block looked like
with the thumb screw and what is now planned.
Of course, the final shape of the knob will change from the simple
cylinder shown as the part develops.
The thumb screw replacement starts by cutting pieces of
¼”-20 treaded rod to length. The actual
cutting is done using a jig saw with a metal cutting blade. After wrapping the rod with masking tape and
marking the needed length on the tape the rod is clamped between two scraps of
wood that have a 7/32” hole drilled in them.
The thing that looks like big nut just to the left of the wood clamp is
a thread cutting die that will clean up the threads once the rod’s been cut.
Here is what the cut ends of the rod look like. They are pretty rough and jagged. Also, while being cut the threads get mangled
making it almost impossible to get a nut started on the cut ends.
The mangled threads are why the die is put on before the
rod is cut so as it is turned off it cleans up and reforms the bad
threads. The left photo is before that’s
been done. The right photo is after the
die cleans up the threads, the end has been ground smooth on the bench grinder
and a small hand file used to touch up the last thread on the end. The same process is used on the other cut end
of this short section of rod.
The wood knobs start out as a square blank that gets cut
into short pieces on the chop saw. A
stop block was not used here because the cut parts are so short, I felt they might get caught by the blade once cut free and kicked out. A
stop on the table saw would have worked but instead I used the dial caliper
locked to the required dimension and marked each one since there are only six
knobs. That mark then gets set up
against the cut line on the chop saw fence and the cut made. Across all the pieces there wasn’t more than
1/64” difference which is close enough since the knobs finished length will be
determined on the lathe.
Once cut the knob blanks get the center located and they
get a hole drilled about three-quarters though the blank for the threaded
rod. Because the knobs are so small a
wooden handscrew clamp is used to hold them flat and in place while being
drilled.
After being drilled the hole gets threaded to
match the ¼”-20 threaded rod that will get epoxied in there. The threads get cut with a homemade bottoming
tap, shown close up in the inset, called that because it cuts threads all the
way to the bottom of a blind hole.
Gluing the threaded rods in place is next.
Next Up – Completing Thumb Screw Replacements & Applying Finish
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