Thursday, June 16, 2011

Eyeglass Case Progress & the Weakest Link!

Soss Hinge aka The Weakest Link
This somewhat blurry picture shows what could be the most difficult part of the project.  These are called Soss Barrel Hinges and they require that 10mm hole, precisely 2.5mm from the edge, 11mm deep, and in the exact same location on both parts of the case.  Here's the dilemma though, they're basically a one shot fit and to make matters worse once you put them into the case you can't take them out.  My first case is off ever so slightly but it's only to antagonize me since it's the one I use.  I'll explain the major steps to this project in pictures to help you understand the dilemma.


This is the template used to rout out the recess for the glasses.  Under the squared off sections on the right side are the holes for the Soss hinge.  After securing the blank into the template I use a plunge router to outline the opening shape onto the wood.  The first case I did I used the router to get down to the 5/8" depth, 1/16" at a time.  If you do the math that's 10 very noisy and dusty passes with the router -- yeech!

Waste removed with Forstner Bit

The easier and more efficient way to do this is to remove the bulk of the material with a large forstner bit.  This is how it looks after that process.  Of course, no step in this project is without it's challenges.  Forstner bits are used to cut a flat bottomed hole ---- but; they have a fairly long spur in the center to help it stay on track.  On the bit I had it was about 3/16" in depth which translates in to many more passes with the router.  I used a grinder to remove the bulk of this spur, you can see the mark it left on the two blanks at the right.  The farthest piece to the right is African Paduak, the other is Goncalo Alves.

After the bulk of the waste was removed with the forstner bit which; by the way,  works great in the drill press my friend so generously gave to me it was back to the template.  A series of cuts were made, about a sixteenth of an inch at a time.  The bottom is still not up to the smoothness I want but no matter how accurate the set up is, trying to smooth an area approximately 2 1/2" wide by 6 1/2" long with a router bit that has a cutting edge of 3/8", it's not going to happen.

Tadpole sander in Spanish Cedar
The next step in the smoothing process is to use a tadpole sander which you see here in the Spanish Cedar box.

     As you can tell there is a ton of hand work that goes into this project.  Before the hinge goes in it must also have radiuses formed on the outside edges, then hand sanded, then shellacked several times, and finally rubbed out with wax and synthetic steel wool.  To think that after all of that I could insert the hinge and find one of the measurements just "a silly lil' millimeter off" kind of sucks and puts lots of pressure on me.  Tomorrow morning (when the shop is below 103 degrees again) I think I'll sacrifice a pair of hinges and ever so slightly grind them down so they will slip into their holes.  If the hole isn't deep enough I can fix that.  If the holes are way off I'd rather sacrifice them then before doing all the work I listed above only to find out they're scrap.
At the Sin City Woodworkers meeting last night someone mentioned that this is a project that lends itself to CNC, computerized production.  That's not the point of my work, I want to create genuine, hand crafted items.  My preference is for furniture but with todays market, anything I enjoy is fair game.

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