Trackerbar pt. 1

 I started work on the trackerbar today. I first used my steel rule and marked off the position of the holes on a piece of paper. Just to be safe, I double checked it against the Melvyn Wright test roll holes to make sure everything lined up. I then made a photocopy of the template (just in case) and I cut it out and glued it to the top of a 1" x 3/8" length of the mystery hardwood that I've got so much of.

I made a jig for drilling on the drill press and figured out a way to attach my digital calipers. I first drilled all of the holes with a 1/16" bit to serve as a pilot hole, and carefully double checked my measurements with the caliper jig as I moved the piece along. Rather than "zeroing out" the calipers after each hole, I went with cumulative multiples of 6mm as I went down the row (9mm for the last 3 holes).
(On a test piece of wood that I had tried earlier, I zeroed out the calipers after every hole, and the minor variances added up along the way and threw the measurements way off.)

After I had all of the holes drilled to their proper size (5/32"/3.96mm for the first 17 and a "C"/6.14mm drill bit for the big three), I stood the piece on its side and cut it in half.

This left me with two identical trackerbar pieces, which I figured I might need if I really screwed the first one up somehow. As it turns out, the half that was originally on the bottom during my drilling, was pretty fouled up on the bottom side due to splintering from the drill bit. I could still use it in an emergency, but it would require a lot of sanding to make it sound.

Next, I set to work with my needle files and squared of the leading edge of the holes (after double and triple checking John Smith's instructional video to make sure I had them pointing the right way.)

Then I double and triple checked the video again and marked off the back of the piece so I wouldn't lose track of which holes widened in which direction.

To gouge out the back of the holes, I used a rotary cutting bit on a dremel tool and worked my way along very slowly and carefully.

 Here's what it looked like after all of the machining and filing.

I found that a rolled up scrap of 220 sandpaper made a good file for getting the little fuzzy bits out of the holes.

Easy fake brass finish

Thinking that I should probably give my steel crankshaft parts a coat of shellac to keep them from rusting, I thought I'd try an experiment with a mixture of shellac and a few drops of yellow food coloring.

I brushed two coats on a scrap of aluminum rod, one coat on the top of a razor blade, and two coats on part of a chrome-plated shaft, a ball bearing housing (avoiding getting shellac inside), a piece of steel from a ratchet, and part of a slotted screwdriver shaft.  I'm not sure how well the colorant will resist fading - especially prolonged sunlight exposure, but for the interior organ parts I may give it a go.

Back to the crankshaft

Now that I've got the reservoir/bellows assembly fairly complete, I figured I'd better return to my work on the crankshaft, since my first attempt with it failed so miserably.

I originally attempted to make the crank arms out of aluminum, but those turned out to be too soft, and the holes for the shaft widened out enough to make the shaft wobbly and useless. So I repeated the machining process, this time from a solid piece of 1/2" x 1/4" steel bar. This time, to ensure a tight fit, I drilled the shaft holes with a "D" sized drill bit (0.246"), which is slightly undersized for the 1/4" shaft. The shaft wouldn't quite fit into the holes, so I drilled them a little on both sides with a 1/4" bit, leaving about 2 or 3 mm. in the center at the smaller "D" size bore. I then polished the steel up so it would look as shiny as the chrome plated shaft steel, using 220 then 1000 then 1500 grit wet sanding, and finishing them to a near mirror finish with some white rouge polishing compound and a felt wheel on the dremel tool.

I then hammered the shaft sections into the crank arms and got a super tight and square fit for all the pieces. Even though there was no lateral or axial movement, I decided to play it safe and drill completely through the arms and shafts and tap in some 3/32" spring pins. I put a drop of loctite in each of the spring pin holes before inserting the pins. I would have used loctite on the shafts ends, but they were in so tight that the loctite couldn't find a gap to penetrate.

Here are most of the part laids out. I haven't attached the single arm/short shaft/rod end to the end yet, as I'll likely wait until I have it installed through the wooden panels. I'll also wait until I've got the whole pressure box assembly built, so I can tell how much to trim off the end of the shaft where the crank would traditionally go, since I don't want that part of the shaft protruding from the case.

Centerboard Valves and Reservoir Test

Last night, I finished up the bellows/reservoir box (except for the spring fittings). The centerboard valves still needed to be done, so I laid the two pieces of 7" x 1 1/4" blackout cloth over the rows of holes, and glued down a 1/8" x 1/8" strip between the valves to prevent any possibility of a cross draft from one valve that might disturb the seal of the other. I secured each end of the valve cloths with a spot of glue then fixed a couple of hardwood strips at each end to keep the valves and the center strip in place.

Here's a wider view of the completed valves

Then I put the self-adhesive foam weatherstripping around the base of the reservoir box, staggering the seams at the corners. I doubled the width of the weatherstrip, which left me about 1/16" too wide, but I decided that it was OK if there was a little excess on the interior side of the box.

I wasn't enthused with the grey foam, so once it was all stuck on, I decided to color the edges black

I used a Sharpie for the edges, which had the added benefit of hiding the rough seams somewhat

I think the black foam wound up looking less conspicuous, and once it was compressed, it looked like black felt more than foam.

I realized that I needed screws longer than the 3/4" No. 6 brass wood screws I had on hand, if I were to penetrate the plywood of the centerboard and get down to the hardwood strips below (Except for the side nearest the pipes, which has no hardwood below it). At first I was determined to make a trip to the hardware store for some 1" screws, but I got impatient and decided to use my 3/4" screws and countersink the screw holes in the battens by 1/4" deep using a forstner bit. I got everything put together and then gave it a test using a 2.5lb (1.1kg) weight to see how fast the reservoir emptied.

Here's a short video clip of the test:

Relief Valve and Reservoir Outlet

Continuing work on the reservoir box relief valve. I trimmed the base of the hinge and worked out a way to have it serve as the base of the spring as well. I attached the relief valve trigger arm to its base with a countersunk brass screw and some wood glue.

Then I stained everything with a mahogany stain, and made the valve seal out of a piece of chamois with a blackout cloth backing. My first two attempts at this backing failed. I first attempted using hot glue to try and seal the rubbery side of the cloth with the chamois, but the glue was too lumpy, and seemed like it wouldn't make a nice smooth sealing surface once assembled. So I then glued the cloth side to the chamois with wood glue, and then glued the rubbery surface to the bottom of the wooden pieces with the hot glue, but the bond did not hold. Finally, I found an old tube of contact cement, and that did the trick. I clamped everything for a few hours just to be safe.

Once the chamois/cloth facing was nice and secure, I worked on adding a piece to hold the spring in place. I used a small drill bit to carve grooves in the wood for the spring wires so I'd have a nice surface fit.

 While I was letting the glue continue to dry, I worked on getting a small piece of copper pipe cut. The 3/4" pipe was a slightly loose fit in the reservoir air outlet block that I had drilled with a 3/4" forstner bit, but over the past week or so, I've been applying layer upon layer of shellac in the hole hoping for a snug fit. I cleaned the copper pipe, cut about a 3" length of it and did a diagonal cut across the bottom of the pipe so I'd have decent airflow through the elbow of the block.

The repeated coats of shellac turned out to be beneficial, because I needed to use a hammer to pound the pipe into the block. It seemed like a nice tight fit, but just to be safe, I covered the joint with another coat of shellac, and shellacked the bare copper as well.

Returning to the relief valve... I knew there would be upward force on the hinge base caused by the spring, so I figured that a nut and bolt through the reservoir box lid would be most secure. I figured screws wouldn't be secure enough, especially since they'd only be grabbing the thin 1/4" plywood of the lid. Unfortunately, I didn't have any brass nut and bolt pairs, so I used a steel bolt, and figured out a way to completely hide it from view.

Here's the relief valve all put together, crazy curly-Q springs and all.

Looks like it will soon be time for a pressure test!

Reservoir Cloth, Centerboard and Relief Valve Parts

 After work, I had some time, so I thought I'd get the reservoir cloth on. This was definitely easier than the cloth on the bellows - partly because this isn't my first time in doing this now, partly because you can see inside the box the entire time, so it's easy to inspect for mistakes.

After the cloth came out from under its 30 lbs. of clamping weights, I attached the side and end battens with glue and secured them with #2 3/8" brass screws from the inside of the box. I predrilled, stained, and shellacked the battens and the air outlet block, but I'll probably give all of the joints another round of shellac once the cloth glue is fully cured.

I also put the temporary battens on the centerboard halves, fitted the center strip and glued over a piece of blackout cloth using a rubber typesetter's roller to get it down flat and smooth. I think I'll go over this seam with some shellac as well. I also sanded down the areas where the valves and valve mounts will be going.

While everything was drying, I cut out some pieces that I'll be using to make up the relief valve. I left the valve arm purposely long, so I can cut it to fit once the bellows/reservoir assembly goes into its eventual position. At the fabric store last weekend, I found something called "jeweler's memory wire" in a gold finish. This is fairly stiff wire with very good spring capabilities, so I'll try to fashion some sort of spring out of it for the relief valve.

Trying some hand-painting decoration

Having the lid to the reservoir box stained and sitting around for a while, I kept thinking that it looked like a big rectangle begging for some sort of decoration. I've also been wanting to practice a little hand-painting of designs, so I figured this would be a good testing location - If it worked well, great. If not, then it's really hidden inside the organ and wouldn't be subjected to close inspection anyway.

So I looked around the web for a design/decoration that would fit in with my overall concept of the organ, and I found this image, which I really liked for several reasons:

I brought the image into Photoshop and did some stretching so it would fit in with the aspect ratio of the area I intended to put it on the reservoir box lid. I also ditched the little crown on top, and I made it a multi-layer image with separate layers for the black fill area and the gold outline area.

I set up an LCD projector which I connected to my computer and rigged it up on an overhead stand so that it would project the computer screen to my table top. I aligned the reservoir box lid and once everything was lined up, I used some gaffer's tape to hold the lid into position. I then turned off the black fill layer of the image and started work painting in all of the gold outline areas. (I used Testor's model paints for both the gold and the gloss black.)

Once I had the gold areas pretty much filled in, I turned off the projector and touched up any areas that needed it.

After letting the gold layer dry overnight, I returned to the painting, this time with the black fill layer visible.

I used a fine-tipped cheap brush and worked my way very slowly. I don't have much experience in this kind of painting - most of my painting has been of the roller and tray variety.

And here's what I wound up with. Once it dries completely, I'll drill the hole for the relief valve and get to work on the cloth...

Incidentally, the original design is the monogram of Johann Sebastian Bach, which cleverly contains the initials JSB. I thought this was very fitting for the John Smith Busker.