Wood Body Pinhole Camera - #4 Routing Dados, Tenons, Machining Top & Bottom

Here is the router table setup to cut the ¼” wide and ¼” deep dados.  The cut depth and location has already been set using some of the test material.  Some things to notice about the setup.  First, to keep the blank square and to minimize blowout when the bit exits the piece there is a ½” thick backer board.  It also has a handle to help me control the cut.  Next, the blank has not been cut to size.  It is too wide and the side piece is still attached.  Width is oversize because I anticipate a little blow out on the back side even with a backer.  If so, it will get cut away when I trim the blank to its final width.  The extra length is so if the first cut goes bad it can be cut off and redone.  Last is the thin plywood spacer under the piece shown better in the bottom photo.  I will go into what that is for next.

In this closeup the piece has been run through the router.  The width and location are set and correct but the depth of the cut is way short due to the spacer holding the piece up.  That’s done because trying to remove all the material in a single pass can lead to problems like overloading the bit and breaking it or since it’s a closed cut the waste can pack in the cut leading to overheating the bit and ruining its cutting edge.

Here is the second pass made using a thinner spacer which makes the cut deeper.

This is the third pass which cuts the dado to its full depth.  Another way to make the cut would be to raise the bit in three steps.  I didn’t do that for a couple of reasons.  First, using spacers for the first two passes leaves an opening under the blank allowing the chips an easy way to escape preventing it from packing them in the cut.  For the third pass there is a lot of free space within the dado and not a lot is being removed during this final pass.  The other reason is once the bit and fence are set with spacers I can cut as many pieces as I want and they will all be the same.  If the bit were changed for each pass and during the last pass on the last piece a problem developed where I needed to make another piece the bit would have to be reset to start from the beginning.  Trying to get the exact same depth of cut can be done but it sure is fussy time-consuming work.

Routing the tenon to go into the dados just completed is next.  The same three step routing process and bit are used although the distance the bit is from the fence is changed. 

Once the tenons are cut the fit into the dados is checked.  Because the dado is cut using the full diameter of the bit they are all the same width.   However, the thickness of the tenon will vary ever so slightly because the cut removes a fixed amount of material rather than cutting the tenon a fixed thickness.  If everything were perfect the tenons would be the same thickness and would fit with no problem.  Unfortunately, I don’t live in a perfect world and there is some variance in the thickness of the pieces.  It’s not much maybe a few thousandths of an inch from one side to another but that’s enough to impact the fit.  The fix it to mark where the tenon needs to be trimmed and clean it up.  To do that the thick part of the tenon gets marked then clamped down.  The top photo shows my clamp assembly.  The bottom photo shows the pencil mark where material needs to be removed and next to it is the file I will use.  Filing just enough to remove the pencil line generally takes care of it.

Ripping the top, bottom and sides to their final width is next.  Most of the time I keep a combination blade on the table saw.  It’s a comprise design that does a pretty good job for both ripping and crosscutting.  Still, using a blade specifically designed for ripping does give a better cut so I changed out the combination blade for a rip blade to make the cuts.  Below on the left is the combination blade and on the right the rip blade.  Note the difference in tooth configuration.

In order to clean up any chipping from the routing I start by taking a very thin cut from one side then cutting it to the finish width on the other.  This is what the dry fitted box looks like.  Nice clean tight joints where everything lines up.

Drilling holes in the top for the knobs and magnets is next.  The top photo shows the plan and the bottom one shows the layout with the centers punched to make centering the drill easy.

The drill press makes quick work drilling through holes for the knobs and their axels.  The holes for the magnets are drilled just deep enough so they will be flush when installed.

Installing the threaded insert in the bottom so the camera can be mounted on a tripod is next.  The insert has wood screw threads on the outside and machine screw threads on the inside.  I have a couple different types of inserts.  The one below on the left is plated steel but is longer than the bottom is thick and would stick out.  The middle one is also a little long but it is made from brass and unlike the plated steel one I can shorten it to fit without worrying about it rusting.  Besides I like the look of brass with cherry.  The one on the right is the shortened one that will be installed.

A 10 mm bit is used to drill a hole for installation.  It is just a little larger (.0187”) than the 3/8” bit used for maximum strength which is not needed here and makes for a much easier installation.  Here in the top photo you can see where the insert has been screwed onto a partially threaded rod along with a spacer and wing nut all chucked up in the drill press.   To install I lower the chuck using the drill’s handle and turn the chuck by hand.  As I have said before don’t turn the drill press on to install the insert or things will get really exciting in hurry and not in a good way.  Using the drill press to install the insert most of the way makes sure it is plumb and square.  The bottom photo shows the underside of the bottom with the insert installed.

Next Up – Starting the Film Knobs