Mounting the tracker bar and fitting the tubes

Now that I've got the pressure box window installed, I'm eager to see whether the pressure box will indeed hold any pressure.

Since I've got no holes in the back or side panels, the only places where air can leak are: around the take-up spool shaft, the tracker bar base, the lid seal, and the lid window seal. Of course there could be leaks around any of the panel joints as well.

Since I've put an oil/air seal around the take-up spool shaft, that should be OK, and I'm fairly confident in the 4+ coats of shellac on all of the wood panels and joints. So, I decided that the next step was to get the tracker bar mounted.

I drilled the tracker bar base ends and used it to mark corresponding holes in the tracker bar platform, then I fitted the bottom of the tracker bar with some strips of foam weatherstripping (coloring the grey foam black around the edges with a sharpie).

I attached it with some brass machine screws and nuts:

Then I fit my crazy brass tubing to the bottom side of the tracker bar:

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Attaching the spool drive wheel

So with it raining cats and dogs only 2 days after my wife moved all the table saws out to a new shed she built, I've been puttering around looking for some other things to do inside the house.

I polished up and shellacked my brass tracker bar tubing, and while waiting for that to cure I thought I'd get the spool shaft drive wheel fixed into place.

After thinking of various possibilities and looking around at what I had on hand, I decided to attach a black oxide shaft collar to my wooden spool drive wheel. I have a bunch of small roll/spring pins and I figured that I could drill holes partway into the shaft collar sides so that the pins would sit halfway in. The protruding parts of the pins could then be secured into the wooden wheel:

Driling was a little tricky but using some vise-grips to hold the collar under the drill press made it a little easier.

I then slid the spool drive wheel and the shaft collar onto the shaft to align them and then pressed the shaft collar's pins into the wooden wheel to mark a couple of drilling points.

I then drilled into the wood, pressed the collar into place, and gave the collar a coat of silver paint.

I put a nylon bushing on the shaft and then slid the collar/drive wheel unit onto the shaft.

I'll cut the shaft a little more closely when I get all the mechanical stuff finalized.

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Pressure box window

Continuing work on the pressure box, I wanted to attach the lexan window in place, but realized there were several things I had to do first.

First off, my 7" diameter lexan circle was just a little too large to fit in place between the strengthening strips on the underside of the pressure box lid. Armed with my 100 grit sanding block, I filed down a couple of edges so I could fit it in. Then, using a printout from the original scrollwork pattern, I marked some drilling marks for the pilot holes for the mounting screws. I drilled holes through the lexan then, holding a tiny drill bit between my thumb and forefinger, I "hand drilled"into the underside of the pressure box lid using the piece of lexan as a guide.

Using a variation of an idea suggested by Steve Toyne on the forum, I next cut out a ring of chamois to act as a gasket between the lid and the lexan. At this point I had to put the window on hold as I realized that I needed to complete the exterior finishing of the lid before affixing the window, as it wouldn't do to have stain, sanding dust, shellac, etc. falling down onto the window. Even though the window would be screwed in place rather than glued, I didn't want to wear out the holes by working the screws repeatedly (the panel plywood is only about 3/16" thick).

I'd been planning on doing some ornamentation of the window scrollwork, and I thought about doing some gilding around the edges. I've never done any gilding before, but I thought I'd give it a try.

I first used a Krylon "leafing pen", but it really just looked like gold paint. I figured it would make a good base to the metal leaf in case I had some spots where the leafing didn't stick.

It took me a couple of attempts to get the hang of the metal leafing, and it left a lot to be desired upon close inspection, but the difference in reflectance from the gold pen was pretty dramatic when angled around under lights.

Next, I shellacked the top with 3 coats and baked it for an hour in the oven at about 175ºF in order to even out the brush marks a little. Once it was dry and cooled down, I set to work attaching the lexan window.

Since the chamois gasket/seal passes under the mounting holes, I used a push-pin to punch through the chamois and mark the holes.

Here's what it looks like with everything in place on the underside:

And here are a couple of views of the top side:

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Spending way too much time on the spool...

Having a nice wooden cylinder for the take-up spool made me want to skip my original plan of using MDF for the spool ends or "cheeks", so I thought I'd go with real wood instead.

I glanced at the plans for the diameter measurement, found a suitable piece of basswood and cut out a pair of circles. Not having done anything on the scroll saw for a while, I decided to "fancy up" the spool cheeks with a scrollwork pattern:

After I drilled and cut one of these I wanted to see if it looked OK next to the cylinder, but when I held the two together, something didn't look quite right. I looked at the plans again and realized that I had glanced at the wrong measurement - I cut my circle at 3 3/4" diameter (spool wheel diameter) instead of the proper diameter of  4 1/4". This threw me off, as I now had to re-think what I would use for material since my basswood was only 4" wide.

I tried a piece of plywood, but didn't like the way the thin outer ply wore off when I sanded/chamfered the edge. I figured I might just sand off the whole thin outer ply, but when I did, the piece started curling. Next I tried gluing two pieces of basswood together side-by-side, but the joint seemed too flimsy. Finally I found a supplier in downtown L.A. who carried basswood in 1/8" x 6" strips, so this is what I ended up going with. Since I had to wait for the store to open the next day, I started work on the interior parts of the spool, and came up with a contraption to lock the spool to the shaft:

The locking mechanism consists of a flat piece of brass, a t-nut and a bolt, plus a screw to hold the brass piece in place. I put this into a hardwood circle to fit inside the center of the cylinder. Basically, the bolt passes through the paper hook hole and pulls the t-nut and plate tight against the spool rod. This gives me an easily accessible way to make side-to-side adjustments in the spool position, as I only have to loosen the bolt with a blade tip screwdriver, slide the spool over, and re-tighten the clamping bolt. I'll probably grind a flat spot on the middle part of the shaft to ensure a more reliable lock.

After getting the 6" basswood, I made a new pattern, and modified it down from 8 sections to 6, and changed the rectangular cutouts a little to make it easier and quicker on the scroll saw:

After they were cut, I sanded and stained the cheeks and glued them to their internal cylinder ends. Here's a pic of them clamped together back-to-back as the glue sets with the spool shaft in place to keep everything aligned:

After staining and shellacking (1 coat so far) here's what the spool looks like:

For the paper roll hook, I took a small brass cup hook and cut most of it off, then bent it and screwed it in place.

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