Before putting the sliding assemblies together, a stop
gets added to the leveling bar on the first and last assemblies. The stop locks the piece to be surfaced in
place so it does not slip and are replaceable if they get damaged in use.
Assembly consists of feeding the bolt through the hole in
the leveling bar, threading it into the wheel then running the bolt into the
threaded hole in the sliding base until the head is just about ¼” above the
bottom of the leveling bar. The whole
assembly is then flipped over and a drop of Loc-Tight is put in the bolt hole
from the bottom. The bolt is then run in
until it’s level with the top of the leveling bar. As it’s run the rest of the way in the
Loc-Tight gets spread on the last ¼” of threads locking them in place. Here is the completed assembly.
After putting all the assemblies onto the sled base it’s
time to do a test run of the sled. For
that I took one of the unusable twisted and bowed 2x4’s from the just completed
Glider/Swing cut it in half and set it on the work bench. To get an idea of just how bad the twist is a
couple of straight wood pieces are set on the wide face of the piece. You can see the result below. If the piece had been flat the tops of the
two pieces of wood (red arrows) would be parallel. The more twisted the piece the more they are
rotated apart and this one is pretty bad.
What does not show up very well is a bow along the long dimension that
also needs to be fixed.
To use the sled the end assemblies are brought up snug to
the end of the piece to be flattened and locked in place using the small knobs
at the base of the sliding assembly. The
remaining assemblies are evenly spaced out between the ends and locked in
place. Starting with the end assemblies
the wheels are adjusted up and down until the leveling bar is parallel and
touching the bottom of the twisted board.
The same thing is done at the opposite end. Next measurements are taken from the high corners
down to the top of the sled. They
probably are different but by using the wheels to raise or lower the high
points the board ends can be moved up or down until they are close to being the
same. That’s done so equal amounts are
taken off of each edge to minimize the total amount of material to be
removed. Once the ends are set the rest
of the leveling bars are brought up using the wheels until they are just
touching the underside of the to be flattened piece. At this point the piece will be solidly
supported so it does not rock from side to side. If it rocks then the adjustment of the
leveling bars is off. The top photo
shows all that done. The bottom photo
has the piece removed so you can see how the leveling bars have been adjusted
to follow the twist of the piece. The intermediate assemblies also keep the board from bowing under the roller pressure when fed through the planer. 
In this photo the sled, planer, support and vacuum are all
set up and ready to go. The support
helps me keep the sled level when feeding it through the planer. If you compare the ends of the board, you can
see how much twist there is in it. At
this point the face of the board gets cross hatched with a pencil to act as a
visual guide when surfacing.
After the first pass the high corners are planed off
shown by the partial removal of the cross hatching on the piece’s surface. The top photo is the left end and the bottom
photo is the right end. The area still
to be flattened is angled which makes sense as the closer one gets to the
center of the board the less apparent twist it has.
After three passes through the planer all the cross
hatching is removed resulting in this face being flat and true. The photo below shows a close view of the
left and right finished ends. Next is to
flatten the opposing twisted face to bring is parallel to this face. 
To flatten the second side the piece is removed from the
sled and the newly surfaced flattened face is placed down in the
planer. The planer is then adjusted to
take start taking off material. Below is
a close view of the left and right ends ready to be run through the
planer. As with the first side it is run
through the planer until the crosshatching is removed. When that happens, the opposing faces are
flat, parallel and true.
To check and see if the twist has been removed the piece
gets set back on the workbench and the sticks use to check for twist are put
back on. The top photo shows the twist
before being run through the planer using the sled and the bottom photo after
flattening shows the sticks parallel to each other indicating the top and
bottom faces are coplanar.
With the top and bottom flat and coplanar there is one
last set of cuts that have to be made.
The sides are not square to the flattened/coplanar top and
bottom. That’s because while the sides
were originally square with the faces when the twist gets removed the sides are
no longer square. In the top drawing
below the red and green areas illustrate the twist of the original board. The crosshatched area is what the final
squared board should look like. The
bottom drawing is after the board has been flattened using the planer and the
sled. What’s left is the little out of
square triangles on sides which get cleaned up next.
To square the sides the tablesaw is used with an 8’ long
level acting as a straight edge. Process
is to see which way the board is curved and put the center high point side
toward the saw blade. This makes just
the ends of the board run along the level with the bowed gap along the
center. A skim cut is made to remove the
bow and make the outside edge square to the faces. That edge is then flipped so it is against
the level. The fence is then adjusted to
make a skim cut on the second edge which trues it up. This gives the flat, straight and square
board like the one that’s setting on the table saw. If you look to the left side of the photo the
sled is setting there.
I have to say the results are even better than I had expected with no twisting or bow detectible at all. There is little learning curve in adjusting the intermediate leveling bars but the adjustments go quickly. The only drawback I can see so far is the length of piece to be flattened is limited to between 12” and 47” long but that will certainly take care of the majority of project pieces that need to be flattened. On the plus side is pieces up to 12” wide can have the twist removed and that’s about a third wider than any jointer I ever imagine getting could do. The other big benefit is the time it takes to do the flattening with the sled versus doing it by hand as the sled is a huge timesaver. The only disadvantage would be a reduction in my cardio workout. 😊
On a side note, part way through
this project I got a note from a person who follows this blog. He said he had a barely used full-size Delta
6” jointer on a floor stand with a mobile base that he no longer needed and asked I wanted it. If so, all I had
to do was come pick it up and give it a good home. Needless to say, I was flabbergasted at the
offer and after making sure he really wanted to get rid of it went and picked
it up. For now, it’s setting in the
garage until I rearrange the shop a bit to give it a home. With this addition I will also be able to flatten
and true up pieces longer than 4’ as long as they are narrower than 6”.
No comments:
Post a Comment