Windchest Part 1:

Design & Layout

I am presenting the construction of my two-rank windchest in 4 parts because it would be horribly long to do it as one post.  It is still horribly long.  But then, it was a really big undertaking.  I began this last summer and worked on it off and on until now.  I wanted to wait until it was pretty much done before posting anything.  That's why there hasn't been much activity on this blog this winter, even though I have been working away in the shop.  Plus, this lets me organize it in more chronological order- I actually skipped around a bit when working on it.  Even though this is a blog format, I posted these in reverse order so they should show up on your screen numbers 1-4 as you scroll down.  Start here and keep reading:

From the start of this whole project, I had the opportunity to add one rank of pipes, possibly two if I wanted a Celeste.  None of these extra pipes were included with my initial purchase, nor was a windchest included to play them.  After deciding to add a Rohrflöte and String Celeste I began searching for an appropriate chest.  I wanted a two-rank chest, "A" layout (largest pipes in the center), electro-pneumatic (EP) action, and absolutely no more than 85 inches long.  Oh- and it had to be within a day's drive of Lincoln so I could go pick it up.  I posted a want-ad on churchorgantrader.com and other websites and checked eBay daily for almost a year with no luck.  What are the chances of finding a used chest exactly as I wanted?  Slim.  I thought about building a Direct-Electric (DE) chest because it would be easier and quicker than EP.  On the other hand, it would cost more money and I wasn't too fond of having two types of action in the same instrument.

A couple years ago, I was talking to Fred Zander (then at Bedient Organs) about replacing a few water damaged pouches in my existing chest.  I mentioned my search for the ideal EP chest and my plan to just build a DE chest instead.  He really didn't like the idea of mixing the actions either.  He pointed out that building EP chests isn't all that difficult, as long as a person's woodworking skills are precise.  It would take more time, yes, but it would be better to have the whole organ on EP action.

This past summer, I began designing the chest.  I knew the basic dimensions, but I hadn't the foggiest idea about how to design the action.  The Organ Supply Industries catalog shows a couple general styles, but no details or construction diagrams.  I called Fred and we met to discuss my project and he graciously offered me some insights and advice.  We looked at both OSI styles and I decided to go with Style 2, in which the pouch well is connected to the magnet port via a piece of vinyl tubing and a boring in the sidewall of the chest.  I had measured the pipe toe openings, and from that calculated the diameter of each toe hole in the chest (chest hole should be about 1.5 times the diameter of the pipe toe hole). Fortunately, the toe holes were all small enough that I not only didn't need to use primary valves, but all of the pouches could be the same size as well.  That made things a lot simpler.  We decided to use a 7/8" valve on a leather pouch 2 1/4" diameter covering a pouch well 1 3/4" diameter by 9/16" deep.  Armed with this knowledge, I sat down to draw out the chest.

As a landscape designer, I have plenty of drafting paper lying around, so I drew everything out at actual size.  I decided to build two matching but separate chests (one for each rank) rather than one big chest.  Being my first windchest, I thought that might be a bit more manageable.  The spacing of the smaller treble pipes was dictated by the size of the pouch and well.  The spacing of the larger tenor pipes was dictated by the diameter of the pipes themselves.  I didn't want to waste any space, but the pipes couldn't bump shoulders either.  I am an old-school draftsman preferring to work with pen and paper instead of CAD, so I started with one sheet showing the pouch wells and added layers of opaque vellum over the top showing leather pouch placement, toe boards, and rack boards.  Then I added layers under it showing the tubing manifolds, bottom boards, and magnets (shown above right).  I also drew a 1:1 scale drawing of the chest in cross section (shown above left).  Remember- you can see a whole album of photos by clicking on the link at the end of each posting.

Now that I had blueprints, I called Fred and he ordered the leather pouches & fish glue for me from Columbia Organ Leathers.  I then bought premium poplar and plenty of 32-pair cable from Bedient.  The best lumber was used for the pouch boards, second best for the toe boards, and good quality lumber for the side and bottom boards.  One of the members of my church has a very nice wood shop with a planer and he let me come by to plane the rough lumber down to the appropriate thickness.

Now it was time to lay everything out.  I cut the pouch board, toe board, and rack board to the exact length.  Each board received a thorough sanding.  I then positioned one atop the other precisely as they would be in the finished chest and clamped them together.  Although the long pouch boards would each be cut into three sections, I decided to leave it as one for now to improve the accuracy of my layout.  On the top of the rack board I marked the toe holes and rack pin holes.  On the bottom of the pouch board I marked the mounting screw holes and guide dowel holes.  Then I screwed the three together so I could drill the pilot holes.  I drilled the toe hole pilots through the rack board and toe board and barely into the pouch board.  This ensures that the rack board hole is perfectly in line with the toe board, which is perfectly in line with the pouch and valve below.  I did the same with the markings on the bottom board, but only drilled into the toe board, not the rack board.  I drilled a 1/4" hole through the pouch board and into the toe board.  This will hold a dowel that will ensure that the pouch board is mounted precisely in place under the toe board.

Next, I unscrewed the three boards from each other so I could drill the pouch wells.  My pilot bit wasn't long enough to all the way through the pouch board, so I started by continuing the pilot holes all the way through.  I then used a 1 3/4" Forstner bit to bore the pouch well because this type of bit is capable of boring large holes with perfectly flat bottoms.  The pouch wells were bored 9/16" (14mm) deep.  Next, I turned the pouch board over and drilled a 3/8" hole through the center of each well.  This hole will be used to center the pouch when laying it, but then also receive the spring that raises the pouch up after playing.

The next step was to layout, cut, and attach the tubing manifolds.  These manifolds hold the vinyl tubing in place under the pouch board and against the side board.  I cut each manifold and glued on a cork gasket before screwing it to the under side of the pouch board (or onto the side board).  This ensures that the well's exhaust port is perfectly aligned with the hole in the manifold, which is perfectly aligned with the vinyl tubing.  Same with the side board manifolds.  Returning to the pouch boards, I drilled a 3/8" hole through the bottom of the well and half-way through the manifold.  When all had been drilled, I removed the manifolds and drilled a pilot hole the rest of the way through the manifold.  I then drilled a 9/16" hole from the opposite side going just over half-way through.  This hole receives the vinyl tubing, and the 3/8" hole lines up perfectly with the inside of the tubing.  On the side boards, I attached the manifolds and drilled a pilot through the manifold and just deep enough into the side board to mark it.  I then removed the manifolds and drilled a 3/8" hole from the side board side and a 9/16" hole from the vinyl side.  I re-attached the manifolds and drilled a 3/8" diameter hole 9/16" into the side board.

Then, I turned my attention to the toe boards.  I wrote each toe hole's diameter on the toe board in millimeters.  Millimeters are much easier to work with than 32'nds of an inch.  I was sure to drill from the inside out because I wanted as clean and crisp of a hole as possible where the valve seats against the toe board.  If there was tear-out on the top of the board (and there was), it isn't a big deal because most of the tear-out was removed by chamfering the toe holes.  If the chamfer didn't get it all, it still wouldn't affect the pipe speech.  I also drilled the holes to receive the rack pins and I drilled the pilot holes for attaching the toe board to the side boards.  Next, I used a large countersink bit to cut the chamfers in the toe holes.  This sunken, beveled edge seats the pipe foot over the toe hole.

The last step in this phase was drilling the hole through the side board connecting the vinyl tubing with the electro-magnet in the bottom board.  I made a fence to attach to the drill press table, holding the sideboard centered exactly below the drill bit and holding it at a right angle.  With some precise marking, these holes lined up perfectly with the holes going from the vinyl, through the manifold, and into the side board.

Design & Layout Album

Windchest Part 2:

Laying Pouches

The next big step was to lay all the leather pouches on the pouch boards.  If you have been following this blog, you may remember that I didn't get any photos of re-leathering the water-damaged pouches in my existing chest.  I have made up for it now with plenty of pictures (and a video, if I can get it to upload).  I started by cutting the long pouch boards into three sections so they would be easier to handle.  Next, I sanded the edges of the pouch well so they are gently rounded over.  If this edge were left sharp, the pouch would rub against the sharp edge each time it plays and could lead to premature failure.  I also inserted the 1/4" dowel for aligning the pouch board to the toe board.

The steps for laying the pouches were exactly the same here as they were a couple years ago when I was repairing the existing chest, but I will go through it again anyway. Plus, now I have photos to share.

1) Cut a 3/8" dowel about 6 inches long.  This will fit through the spring hole and be used to center the pouch over the well.

2)  Apply a thin layer of fish glue around the pouch well.  Do not use so much that it oozes out onto the pouch board or especially into the well.  Fish glue is used because it holds well, but can be cleanly removed if necessary for future repairs (hopefully not for 50 years!).  It also cleans up easily with water.

3)  Put the dowel through the spring hole and hold it several inches above the glue. Place the pouch atop the dowel with the felt washer centering the pouch on the dowel.

4)  Lower the dowel and pouch until the pouch sits level with the pouch board.  Gently press the pouch to the glue.  Wait a moment for the glue to set and gently press down on the pallet until the felt washer rests on the bottom of the well.

5)  Smooth out any wrinkles in the pouch and press the edge of the pouch firmly to the pouch board.

6)  After 24 hours, use the dowel to raise the pouch as high as it will go without stretching it.  Make sure the pallet will rise high enough to seat against the toe board.  Very gently run your finger around the edge of the well.  Feel for stiff places where glue may have oozed out onto the leather.  Use your finger to break up the glue without stretching the pouch.  Sharp bits of glue can wear a hole in the leather causing early failure.  

7)  Carefully untangle the springs.  Stretch the tail out at one end just a bit so it will hold in the board.  Gently place the spring through its hole.  Make sure the spring seats inside the felt washer.  

8)  Use the fish glue to attach a paper disc that holds the spring in place and seals the pouch well closed.

After all the pouches were laid, I attached little spacer blocks 5mm thick next to each mounting screw.  These ensure that the pouch board is always precisely the correct distance from the toe board.  I then mounted the pouch boards to the toe board.  Since I hadn't yet attached the side boards, I was able to clearly see the valves making contact with the toe boards.  Out of 122 pouches, there was only one that didn't quite seat perfectly.  I remedied this by gently massaging the leather to stretch it ever so slightly.  I put the pouch board back in and it was fine.  This photo shows the pouch board mounted to the toe board, but before I attached the sides.

Laying Pouches Album

Windchest Part 3:
Assembly & Finishing


With the pouches laid, I was ready to begin assembling the chest.  I started by removing the pouch boards and setting them aside so they wouldn't get damaged during assembly and varnishing.  I attached the side boards to the toe boards with wood glue and screws.  Next, I laid out the bottom boards.  I wasn't able to do this earlier because I needed to have the sides attached to the top in order to get everything perfectly aligned.  I marked where each hole came down through the side board and met the bottom board.  This told me where the magnet would need to be positioned, so I made a template and marked all the holes for the magnets.  Each magnet needs one hole lined up with the hole in the side board, an oblong hole for the magnet coil to go through, and two pilot holes for the mounting screws.

I drilled a 3/8" hole to align with the side board hole.  I then drilled a hole just larger than 3/8" for the top of the magnet coil, one for the bottom of the coil, and another to connect the two.  It's hard to explain, so look at this photo (right).  I then drilled the pilot holes for the magnet mounting screws as well as the holes for the screws that will hold the bottom boards in place.  These included a countersink for a washer.

With all the holes drilled and most things assembled, I was ready for staining and varnishing.  I stained the exterior with a "golden maple" water-based analine dye to match my existing chest which had been shellacked.  I considered shellac for the new chest, but decided to go with varnish because it is easier to apply to large surfaces with a rubbing pad (I don't have a spray booth or spray gun).  I used the same type of varnish as I used on the console, applying 6 hand-rubbed coats.  I let it cure for about a week before proceeding.

Once the varnish was cured, I was ready to install the magnets.  I got the magnets from Fred Zander; he salvaged them from an old chest that had been retired during a renovation.  I made sure that each magnet lined up properly with the boring through the wood.  A couple weren't quite perfect, so I carved  away a little excess wood and it will be fine.  I then cut and glued a cork gasket into place to seal up the bottom boards.  I used a 3/8" dowel to punch through the cork at each of the holes and then used my handy crocheting hook to pull the cork disc out.  Also at his time, I cut the hole for the PVC pipe bringing wind into the chest.  It isn't ideal to run the wind line through the bottom board, because it is a pain to get into the chest to service it, but with my layout, I didn't have much choice.

Next, it was time for racking the pipes.  Most organ builders have sizing racks set up with holes pre-drilled into them and you just try each pipe in several holes until you find the right fit, make note of the size, and then drill the appropriate rack hole.  I didn't think it was worth creating this sort of rack if I may never use it again, so I made a little rack that is the same height as the actual rack board.  It has a notch in it and you put the pipe on it's toe hole, set the rack beside it and use a calipers to measure the diameter of the pipe foot at just that point.  I put a piece of masking tape on the rack board and as I measured each pipe foot, I wrote its measurement down.  Then, when I went to drill the holes, I had the measurement right by each pilot hole.

I used several types of bits including an adjustable large circle cutter that worked great for the larger holes.  I also drilled the holes for the rack pins.  I then put the racks in place and checked the size.  I thought it would be better to drill the hole a bit on the small side (if I didn't have the exact size bit) and then open it with a file as needed.  Boy, was that a pain!  It would have been far better to drill the hole a bit too large and shim it down with a piece of felt.  But I got it done.  Note: I haven't reinstalled the pouch boards yet.  I knew that if I was filing the rack holes open, I would get lots of sawdust down in the toe holes.  It was much easier to clean up without the pouch boards in place.

Well, I was finally ready put it all together!  I built chest bearers a week earlier and mounted the two chests in place and turned them upside-down on a work table.  I vacuumed each part clean with the shop-vac, and proceeded to assemble.  First, I attached the manifolds to the pouch boards and then screwed the pouch boards into place.  Then, I attached the manifolds to the side boards.  The next step was to install all the pieces of vinyl tubing connecting the pouch manifold to the side manifold.  I measured them all and cut them with a handy pipe cutter from my irrigation repair kit.  Fortunately, the tubing fit snugly enough that I didn't need to use any glue to hold them in place.

Then it was time to pull out the trusty old wiring color code chart and wire up all those magnets.  I used  #14 tinned copper wire for the common buss and attached one of the magnet wires to it.  I then marked each magnet with its pitch & number and laced out the color-coded cable just like I did in all the other chests and in the console (I almost have the code memorized now...).  I then screwed the bottom boards to the chest and attached the PVC wind lines.  I turned the blower on- no obvious ciphers and no major wind leaks!  I tested a couple valves by unscrewing the magnet port and they worked fine!  Tomorrow I am planning to attach the female end to the cable so I can hook it up to the console and test it for real.  I can't plant any pipes on it yet anyway- it's still upside down on the work bench and I need to wait for my next door neighbor to get home so he can help lift it off.  This thing isn't light!

Assembly & Finishing Album

Windchest Part 4:
Testing


After I planted all the pipes and turned the blower on, there were ciphers all over the place.  I was expecting this.  Even though I cleaned all the parts as thoroughly as possible, there were still bits of sawdust in there and it doesn’t take much to create a cipher.  I unscrewed each port to blow it out.  That took care of them all.  I went to the console and played each note a few times and that created several more ciphers.  (Yes, I also finished rebuilding the keyboards this winter- I need to write about that yet)  Most of these new ciphers were fixed again by opening the port to blow it out.

One stubborn cipher wasn't so easy.  I started looking for the most obvious causes and getting more drastic as needed.  First, I inspected the electrical relays to make sure the contact wasn’t bent, or a scrap of wire hadn’t fallen in, making contact.  Everything looked normal.  I confirmed this by unplugging the rectifier, but leaving the blower on.  The cipher continued, so I knew it wasn’t electrical and had to be a problem in the chest.  I thought the gasket around the side board boring may have been damaged and air was leaking out that way.  Nothing obvious.  Next, I gently inserted a narrow dowel into a properly working toe hole to feel the resistance of the pouch.  I tested the cipher and felt pretty much the same resistance, so I knew the pallet wasn’t wide open.  Air was just barely leaking past the pallet so I knew the problem was either with the pallet itself, the leather, the spring, or the toe board.

I took that section of the chest apart.  With the bottom board off I double-checked the gasket to be sure it wasn’t damaged.  It was fine.  Then I took the manifolds out, as well as the pouch board.  Everything looked OK at first- the toe board was smooth and the pallet was clean.  When I pressed down on the pallet with my finger there was noticeably less resistance than other pallets.  The pallet also didn’t sit level when it was “at rest” in the up position.  The leather didn’t feel too loose or too tight on either side, so I suspected the spring.  I removed the paper cover.  Several extra coils of spring were sitting down in the wooden seat.  I gently removed the spring and compared it to an extra spring that was left over.  The offending spring was about 3/8” inch shorter than the spare and was slightly curved too.  I hadn't noticed this when I was putting the springs in initially.  I checked the seat in the pouch board for splinters that the spring could have been snagging on.  Nothing.  So, I put the new spring in & replaced the paper cover.  The pallet was now level and gave the same resistance as the others.

Optimistic, I put everything back together and fired it up.  Silence.  I played the problem note.  It sounded.  I released the key.  Silence!  It was a bad spring after all.  Yes, it was a pain to tear it all apart, but at least I didn’t need to lay a new pouch; it was a relatively easy fix.  The Rohrflöte is painfully out of tune, but the Hook & Hastings Dulciana (which will be my String Celeste) isn’t too bad.  Even though the 8’ octave isn’t hooked up yet, I couldn’t resist the temptation to play a few verses of a couple hymns.  But, it just made me realize how rusty I am!  I need to finish building this thing so I can actually practice!