Router Plane

Monday, May 15, 2017

Japanese Puzzle Box - #3 Sides, Dividers & Start of Ends


Before I get started with the next step in the project I have been asked how many people look at this blog.  The statistics show there are currently about 900 hits a month to the site from 30 countries.  This is way more than what I thought there would be when I started.  I thought my audience would be some of the people I knew who did woodworking and maybe a few others.  In total, probably no more than a couple dozen.   I never dreamed that two-thirds would be from outside the United States and over half from areas where English is not the primary language.

Now that I had the top mostly done I could move on to working on the sides.  The first group of cuts are set up all the same ending up with this groove around the perimeter.  This leaves the two stopped dados laid out in pencil to cut. 

The first is pretty simple, reset the fence then mark the limit of the cut by measuring from the leading edge of the bit minus its diameter and drawing a line on the fence. 

With that done I can route the dado until leading edge of the piece hits the line then carefully back the piece out.

The other dado is a little more difficult.  If I try and cut this one like the first I would come in from the left which because of the router bit rotation would not pull the piece into the fence but try and push it away.  I might be able to make it work but the probability of a problem goes way, way up.  The method I will use is to lower the piece onto the running bit then cut away until the bit exits the wood on the right side.  The starting point is marked on the fence as the distance from the leading edge of the bit to the edge of the board.  Here I am lowering the piece onto the spinning router bit.

Here is the finished side, all cuts are made with the same 1/8” router bit the only change being where the fence is set up.


I can now do a test fit on the side and bottom.  It would not quite go together without using more force than I was comfortable with so I did some light sanding and then the joint fit together snugly.
 
After getting the sides and bottom joints to fit I moved on to the two dividers.  There are tenons on each end that fit into the stopped dados on the sides.  They are cut on the router table using the 1/8” bit.  Once glued to the sides and bottom they provide the structural rigidity for the box.  The front divider also has a notched recess that is a part of the locking system.

This notch has to be very carefully laid out and cut into the divider.  To eliminate the chance of cumulative error in measuring I needed to take all my measurements from the same edge.  To get those measurements I did a quick sketch of the notch then added the individual dimensions together.

I started by putting blue painters tape on the divider.  Then using a dial indicator caliper transferred the notch layout to the piece.  Rather than use a pencil with it’s inherent inaccuracy for layout I used a marking knife to cut the blue tape.  Once done I peeled the cut tape away leaving me a clear dead-on accurate layout for the notch.

Before cutting the notch, I did a dry fit of all the pieces I had cut to see if there were any problems.  The top has to slide smoothly and did hang up in a couple of places but some light sanding made it fit just fine.

I could now start cutting the notch but when I went to get the ¼” Forstner bit needed I found my set only goes down to 3/8”.  On a sample piece, I tried some different methods of cutting the notch but had absolutely no luck in even coming even close to finding a good alternative.  Checking around town nobody had that size bit, the smallest was 3/8”.  Going on-line I found I could get one from Home Depot delivered to the house but the shipping cost as much as the bit.  The other alternative was to have it delivered to the local store for free with me going in to pick it up.  The minor downside is that delivery is a few days out, but I went ahead and ordered it.

While waiting for the bit to arrive I started working on the ends.  The back has some locking rabbit joints like the top and bottom.  The front has the same locking rabbit joints plus other machining for the locking mechanism.  More on that later.

I started by cutting my rough blanks to final width and length then using the router cut the locking rabbit joints on the two side edges the same way as I did on the side pieces.   For the back an additional dado at the top and a wide rabbit at the bottom completes it.  At this point the front gets a rabbit at the bottom.  With all the routing done a test fit showed a small amount of fitting needed since these pieces have to slide as a part of the puzzle. 

The front part still has a fair amount of work to do to it before it’s done but the same day I finished the initial fitting I got an email from Home Depot saying the ¼” bit was in and ready to be picked up.  With the bit in hand I will set the ends aside and go back to working on the dividers.

After chucking the bit in the drill press I set the stop so the hole depth is just short of the final depth.  Next is to set the fence so the bit is right at the cutout in the blue tape.  The fence keeps the holes perfectly aligned as I move the piece to drill overlapping holes.
 
Shifting the fence slightly lets me drill the second row of holes.  It almost seems anticlimactic to wait on the drill bit and then in a few minutes drill just 8 holes in each of the two boxes. 


Taking the part from the drill press and clamping it to the workbench I used a variety of hand chisels but mostly a small one without a handle.  Using them I cleaned out the recess until it was ¼” deep with a flat bottom.

Drilling the holes just short of the final depth gave me some room to clean up the bottom of the recess and get rid of most of the marks left by the bit.  It did take a little longer but looks better.

Here is the box reassembled with the completed divider in place.



Next Up – Adding a Handle to the Small Chisel

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