Planer Sled - #7 Completing Thumb Screw Replacements & Applying Finish

Before turning the actual knobs, I did a test using a smooth surface on the tuned knob to see if that would provide enough grip to tighten things down and to no real surprise it didn’t.  A couple of different treatments to the knob’s surface were tried and the one that worked the best is similar to a knurled finish only at a larger scale.  The test pieces and the finished knob (on the right) with its six rounded lengthwise notches is shown below.

Now the threaded rod can be glued into the knob blank using a 2-part epoxy.  A toothpick places a little epoxy in the hole then the rod gets run in.  The hex and wing nut let me use a wrench to run the rod to the proper depth by measuring what’s exposed using the dial caliper.

After letting the epoxy cure overnight, the threaded part of the knob is run into a jig mounted in the lathe.  Since the hole the rod goes into is threaded when the rod is fully run in it is held tight in the jig.

Next the square blank is turned round to the proper diameter, trimmed to the finish length and the outside edge rounded.  With that done the layout for the lengthwise notches for the surface treatment can be laid out using the reference lines on the jig.  They were added to the jig using an indexing feature on the lathe that can lay out a variety of evenly spaced lines around a turning.

Cutting the slots were as I suspected not an easy task.  On the first test piece I tried to cut a couple of them freehand with a round file.  That took quite a bit of time and was not very good so that method was eliminated.  I thought about building a jig and cutting them on the router table but don’t have a round end bit that small, it could have to be ordered but it’s pretty pricy so that got eliminated.  Next, I tried using a small carbide burr in the Dremel tool making the cuts freehand and it did do a good job cutting but I didn’t do so well guiding it freehand.  What worked is a jig that holds the knob in the right place and guides the Dremel tool in a straight line.  The top photo below shows the final setup and the bottom photo is the burr.

Here is a look on how the jig works.  With the knob locked in the jig the Dremel tool rides along the top of the vice while the shaft of the burr rides along the spacer to make a smooth cut.  All I have to do is control the depth of the cut by making multiple shallow cuts until the desired depth is reached.  The bottom photo shows a completed notch and the short spacer that holds the knob away from the vertical part of the jig clamped in the vice. 

After all the notches are cut the knob is removed from the jig where the just cut rough edges get cleaned up and smoothed using a very small round file.  From there the knob is remounted back in the lathe but this time it’s held away from the jig itself so the sharp back edge can be rounded slightly.  After all I don’t want to cut myself when tightening the knob down.  The last little bit is to sand with the lathe spinning both forward and reverse with 220 and 320 grit paper for a smooth surface.  Forward softens one edge of the notches while reverse softens the other edge.

There is one last set of holes to drill before I do the final sanding and then start the finishing process.  They are for two bolts that act as guide rods while also capturing the leveling bars to the base.  The bolts go in a threaded hole in the base plate and are locked in place using epoxy, Loc-Tight or super glue (cyanoacrylate).  The drawing below shows where they go.

These holes have to line up with the holes in the leveling bars so accurately locating them and setting up stop blocks is a good idea.  The photo on the left shows the center finder being used to set the stop blocks and the right photo shows one of the holes drilled.

Threads are added using a ¼”-20 tap to match the threads on the bolts.  The tap is made for metal but can be used in wood and since the wood is a lot softer than steel, I can use the drill to run the tap in.  The bottom photo shows the hole after the threads have been cut.  This completes 99% of the woodworking so now it’s time to clean up the shop so the finishing can start.

The finish is a sprayed lacquer and I have decided to spray all the parts.  Because of the difference in the various component sizes two different spraying methods are used.  The small parts like the knobs and the wheels get sprayed with the airbrush.  The remaining larger parts have their finish applied with the High Volume Low Pressure (HVLP) sprayer.  Here is the mixing setup with all the various fluids and containers needed for spraying.

The photos below show how most of the pieces are hung so all sides can be sprayed at once.  There are two exceptions.  One being the sled base on the left side in the background of the left photo.  It is set on a rotating base so it can be spun around to make all sides easy to get to.  The other is the knobs most clearly seen in the lower right of the right photo that are screwed into a scrap piece of plywood.  To keep the finish off the threaded rod part of the knob assembly that area is masked off.

After the first coat has dried for a few hours they all get wet sanded with water and a 2800 grit sanding pad.  That’s followed by a second coat, an overnight cure and the finish wet sanding.  This sanding starts with a 3200 grit and works up to 8000.  Below are all the completed parts ready for assembly.

One component not yet addressed but shown in the above photo is the self-stick 80-grit sandpaper strips.  They go on top of the leveler bar as shown in the drawing below and will help grip the board that’s being flattened.  I cut them from a 12”x18” sheet made for a floor sander using a template and sharp knife.  To assure a good bond once stuck in place they are clamped together overnight (right photo).

Next Up – Final Assembly & How to Use

Planer Sled - #6 Assembling Base Plate & Sliding Block – Thumb Screw Problem

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

Planer Sled - #5 Completing Wheels & Sliding Blocks – Base Plate, Sliding Blocks Test Assembly

The next day all the clamps were removed giving me seven blanks for the leveling wheels.  They were momentarily set aside while the rest of the cut pieces were glued and clamped up just like the first set.  In the end I had fourteen blanks, the two extras are for backups if there is a problem.  I also made a design change.  The left drawing below is the original design and it shows a T-nut used to provide the ¼”-20 threads in the wheel to enable it to run up and down the adjusting bolt.  The revised plan on the right is to use a regular ¼”-20 nut set into the wheel and locked in place using epoxy.

Taking the blanks and turning them into finished parts requires a series of seven steps.  The first one is to find the center of the blank.  That’s done using the dial caliper set at half the total width and striking a line from adjacent sides.  With that done a compass is used to draw a circle just a bit larger than the finished size.  Both of those are done in the left blank.  The center blank has a flat bottom hole ¼” deep for the nut to set into.  The far-right blank has had a 9/64” through clearance hole for the bolt to pass through added.

Below the top photo goes through the last four steps starting on the left where the blank has been rough cut to a circle on the bandsaw.  That’s followed by epoxying the nut into place being careful to make sure it’s square with the blank and the spaces between nut’s flats and the wood are filled.  Once the epoxy has cured the surface can be sanded to remove any excess, third from left.  At the far right is the finished wheel.  The bottom photo is of the blank mounted on a fixture in the lathe so the wheel can be turned round.  After all 14 are done they are set aside until needed when I will pick the best 12.

Now it’s time to go back and do more work on the sliding blocks.  Between the time I started on this project and now I decided to change these parts a little.  The top drawing shows the original sliding blocks in the leveling assembly.  Front and back views of the originals are also shown at the top of the lower drawing.  The revised sliding blocks are shown at the bottom of the lower drawing.  Originally there was a T-nut on the outside face of the sliding block that a thumb screw ran into and when tightened put pressure on the base locking the leveling assembly in place.  With the T-nut in that location when the thumb screw is tightened the applied force would try and push the T-nut out of the sliding block.  I didn’t like that so decided to move it to the inside face so the pressure would push the T-nut tighter into the sliding block.  There was just one problem, a T-nut will not fit in the space available at that location.  The solution is to use a ¼”-20 nut epoxied in place just like what was done for the wheels.  The only other change was to lower the hole so the nut could be centered in the available space.

The work starts by drilling the hole so the nut can be recessed flush into the sliding block.  There is not a lot of space on either side where it goes so once the center had been accurately located the center finder is used to center the part in the drill press at the correct position.  A stop block and fence are used so all the parts can be made the same.  The left photo shows the drill press setup with the stop block clamped in place.  The right photo is a closer view.

With everything set the center finder is removed, a Fostner bit chucked up, a depth stop set and the partial depth hole drilled.  That’s all been done in the left photo.  From here it’s a simple matter of clamping the next piece in place, drilling and repeating until all of the six blocks needing the holes are done.  The right photo has the Fostner bit replaced with the one needed to drill the through hole for the thumb screw.  Since neither the fence or the stop block were changed the hole gets drilled perfectly centered in the first one. 

With both holes drilled the nuts could be glued in place.  I used a slow curing (18-24 hour) 2-part epoxy.  That way there is plenty of time to make sure they are in the right place and the space between the nut and the countersunk hole’s edge gets completely filled.  While the gap did get filled the process is a little messy.  The next day it’s time to do some cleanup.  Using three different sanding blocks each loaded with a different grit of sandpaper it didn’t take long to clean the mess up.  The two photos on the right show before cleanup and after.  As the nuts are going to be buried out of sight, they didn’t need to be perfectly clean nor was it required for the epoxy to be kept out of the oak’s pores.  If it had been critical to keep the mess to a minimum, I would have masked off the wood outside the application area and cleaned up the nuts themselves.

Next is to put together the slider blocks and the base plates shown in the drawing below.  It is important to make sure the base plate and slider block is aligned correctly.  If they are out of alignment then they won’t slide easily on the base plate.

To make sure of good alignment they will be put together with screws first.  I can take my time with the positioning before gluing and not have to worry about the parts sliding out of alignment when clamping.  After marking out the screws locations their pilot holes get made on the drill press.  Only one setup is needed as all the holes are at the same place in each corner.  The left photo is the setup with the first hole drilled.  The right photo has the piece flipped so the face is now down and it’s ready for the second hole to be drilled.  The holes on the other end just require the piece be flipped end-for-end.

Next Up – Assembling Base Plate & Sliding Block – Thumb Screw Problem

Planer Sled - #4 Completing Leveling Bars & Starting Leveling Wheels

Shaping the profile at both ends of the leveling bar is next.  Below the top drawing shows the profile as originally planned.  The bottom shows how that was revised to eliminate the 90 degree interior corner by rounding it off.  That’s done because an interior corner is a good place for a crack to start when the member is loaded in use.  An arc reduces the concentration of forces spreading it out across the arc.

After making a template out of scrap its profile is transferred to the actual leveling bar.  Since there are 12 ends to be done, I put together this simple jig to hold the pieces in alignment.  From here all that's required is a simple tracing of the pattern’s profile.

The shaping begins with drilling a hole close to the final size of the corner arc.  Rather than try and measure out where the center point of the arc is I just took the drill bit and eyeballed about where it goes making sure to leave a little material to be removed later on when the curves are all blended together.  The left photo shows the drill press setup with stops set for consistency in drilling and the right is a little closer look.

Using the table saw to cut the left vertical edge is next.  The top photo is of the table saw setup with the stop on the right clamped to the backer board to set the cut’s location.  The bottom photo is a close view with the finished cut.

Next, it’s over to the bandsaw to cut the curved face.

Refining the bandsaw cut into a smooth set of curves is done on the oscillating drum sander.  The first pass is with a coarse grit sleeve and the second with a fine grit sleeve for a smoother surface.  From there some hand sanding with a yet finer grit finishes the transitions between the curves giving the final smooth surface.

The leveling bar parts are complete except for some final sanding and the application of some self-sticking sand paper.

The next part is the leveling wheels.  They will be used to adjust the leveling bars which will provide solid support for the wood planks to be flattened as they are run thought the planer.  The drawing below shows how the wheels fit into the leveling assembly.

There is a dozen of the wheels needed and in the original plans they were made out of ½” plywood.  I really do not want to use plywood because, I don’t like the feel of it or the tendency of its softwood layers to splinter.  However, in this case because of the cross-grain structure of plywood it will be less likely to split versus a solid piece of wood.  My solution is to make my own plywood out of oak.  It’s going to be a little time intensive but worth it.  Since I need to make 12 leveling wheels and each wheel has 5 layers that’s 60 individual pieces.  As it happens in my stack of scraps there are several leftover rips less than 3/16” thick that can be used.  The problem with them is they cupped pretty badly after being cut that thin as can be seen in the photo below.

The problem is mitigated by ripping the 4” wide boards in half on the table saw.  This works out well as the final wheel diameter is 1 5/8”.  There is only one consideration when making the rip and that is to have the cupped edges up like in the top photo.  If the cut was made with the cup down then when the rip is done the pieces will fall down onto the saw’s top possibly getting pinched against the blade causing a kickback shooting the piece right at me.  Believe me that’s something to be avoided.  The bottom photo shows how much less cup there is to take care of after the piece has been cut in half.

Thickness sanding to flatten the piece and bring it to the final 1/10” thickness is next.  That starts by placing the crown of the cup up and marking it with a pencil.  The top photo has that done and is ready to be run through the thickness sander.  After a couple of passes most of the crown is gone as shown in the bottom photo.  A couple more passes and the opposite side will get the same treatment to flatten it also.

Once flat the pieces continue to get run through the sander gradually reducing the thickness to the required 1/10”.  The top photo shows the completed edge and face.  Cutting to length is next which is done on the chop saw with a stop block.  The bottom photo shows most but not all the stacks of pieces needed.

Because there are a dozen wheels, I worked on a couple of simple jigs to make the gluing process go faster and easier.  The top photo is of the main jig empty and the bottom one is the first of two batches of wheel blanks glued up.

Stepping back to go through the process here are the blocks used to hold the small individual layers in place while the glue is spread on them.  Note how the grain in each layer runs 90 degrees to the adjacent layer.  The bottom is a closer look after the glue has been applied.

With the glue applied the five layers are stacked up to make a sandwich.  The stack is moved to the clamping jig as show here.  To keep the piece from getting glued to the clamping surfaces the base is covered with a 6-mil piece of polyethene film and the back stop is covered with clear packing tape.

Next in the top photo a clamping block also covered with packing tape is clamped to hold the glued layers in place.  That’s followed by a caul on top of the stack to spread the clamping pressure evenly across it.

Next Up – Completing Wheels & Sliding Blocks – Base Plate, Sliding Blocks Test Assembly