Build day 8: Top braces begun. Plus a light switch!

I took today as a vacation day – so I had some time to work on both my microshop and the guitar. The one thing I wanted to take care of was the damn light switch – it’s been hanging on a wire outside the shop for long enough. I routed the wiring through the wall studs, cut a hole for a light switch to be mounted on the wall, and wired it up. Much better!

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Now that I have a Go-bar Deck,  I really don’t have a reason to delay working on the top bracing any longer. But I still didn’t have anything resembling a radius disk, so I went low tech to come up with a solution. The idea is that while clamping down the braces, something needs to support them at close to the proper radius.  I had read one idea that should work that involved index cards – I read that as ultra cheap – so what the hell, lets try it. I clamped down one of the longest braces at the center and slid in one index card after another, filling the gap with ever more cards. Then I taped the stack together with masking tape. This worked quite well – so I made several more curved cauls this way.

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With that puzzle solved, I could work on fitting the braces to the top. I penciled the brace positions using the blueprint, and then made notches where the braces meet.  Then I sanded and formed the braces to fit.

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It’s finally time to glue the x-braces in place!  The Go-bar deck worked well – however there is one annoyance I may want to fix. Turns out that 3/4″ plywood I used flexes a small amount when enough bars are used – the net effect is that often putting a bar in could reduce the tension on another enough that it will pop out. I did get used to it a bit with some practice, checking the tension often on all rods. I think I’ll get around to reinforcing the top and bottom of the deck with MDF, but this will work for now.

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Afterwards, Tim and John came over for some catching up, some pizza, and some guitar playing. A fun evening after a full day!

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Making a Go-bar Deck

Building a guitar poses many challenges, and most of the problems encountered have more than one solution. My next step is gluing the braces to the top and back of the guitar, but how to clamp them properly is one of those challenges.

The problem is that the bottoms of the braces are curved (front and back have different radii), so you really can’t just clamp them to a flat surface. Now, you could just use lots and lots of expensive clamps with many cauls – but most luthiers use what is called a go-bar deck. The basic idea is that you apply vertical pressure using rods (usually fiberglass) under tension. The second part of the equation is to press it all into a disk with the correct radius, but that’s not todays problem. Today, I made a go-bar deck myself, because I didn’t want to spend $150 on a deck and $4 for each rod from LMI (which is actually one of the cheaper sources).

Here’s what I did. First I cut some 3/4″ birch plywood to make two 20″x24″ pieces.

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Then I drilled holes 1 1/4″ inches from each corner (3/8″ diameter for the top, 7/16″ for the bottom). Into the bottom holes I hammered some 3/8″ t-bolts.

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Next step was to screw four 3/8″ threaded rods into the t-bolts in the base. I slipped some 3/8″ inner diameter plastic tubing over the rods so the threads won’t damage the guitar. Screwed down wing nuts on each rod to approximately 2′ from the bottom.

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Then I put the top on, screwed in with wing nuts. That left about a foot of rod I didn’t want, so I cut the rods to the correct length with a Dremel and a cutoff disk.

Next for the rods. What I used was those fiberglass poles you use to mark your driveway in the snow. By cutting them up I could make 15 2′ rods for less than $1 apiece. Using the Dremel again, I sliced up a bunch of rods to the correct length and put screw protectors on each end (a.k.a. rubber tips).

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Actually the hardest part was getting the tension right. It was tricker than I thought to get the right length of bar vs. distance between the top and bottom. You want the bars to slightly flex when they’re wedged between the surfaces, but 1/4″ one way or another makes a large difference in tension. The reason for the wing nuts is to be able to easily adjust the distance between the top and bottom and therefore the tension on the rods.

And I now have a go-bar deck – total cost WAY, WAY, WAY less than buying one!

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I still have to make some sort of “radius disk” – without spending nearly $80 on each one (I need two, one for the front radius and one for the back radius). That problem is for another day.

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Shelves. You know, to put things on.

Today, I worked on the microshop itself. Before I go much further on the guitar, I need to do a few things first. One thing is to make better use of the other half of the small space – the part under the stairs and the inset into the wall.

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I could really use some shelves. So today I built them.

First I put in some pine siding and some molding to frame things:

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Added some 1×2 to the walls to rest the shelves on – using mostly anchors, since there was only one stud behind the sheetrock.

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Then cut some 1×10 pine to fit each shelf with notches to go around the molding. And had to clean up, of course, which is definitely not my favorite thing to do. To chilax after that, I watched The Office on Hulu.

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Update 1/27/2013

I wanted to finish the shelves in some way – raw pine just gets dirty too easily. So I sanded all the shelves down and applied a coat of lacquer.  I used lacquer because it dries so quickly. I knew lacquer needs serious ventilation – but OMG, even with my three stage filter and doing my best to vent, it still stunk up the entire house. I had to open a window in the basement and hang a box fan from a pipe to pump in fresh air. I won’t be using laquer in the house again. Anyway, the shelves look great.

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Build day 7: Rosette scraped, braces started, and other stuff

Tonight I started by learning how to sharpen my scraper. Armed with a YouTube video and some written instructions, I filed, honed, and burnished a rectangular piece of thin steel as best I could muster on my first attempt. Armed with this unfamiliar tool, I scrapped the rosette purfling until the surface of the guitar top was smooth. I think it came out pretty well, considering I was a bit apprehensive to take a piece of metal to a soft piece of very thin wood.

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Next I could start work on the braces. These are pieces of wood that add strength to the guitar face, so it can hold up to string tension, yet still resonate. First step was to lay them out based on the blueprint I have. I copied the brace layout to the backside of the top.

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Then I took a break, because my good friend Tim White was on NH Chronicle tonight. The opening segment highlighted his awesome invention – The Chrysalis Guitar.  This guitar plays like a high quality acoustic guitar, yet quickly collapses to a very portable size. Check out this video.

Afterwards, I continued to work on the braces, as they need to be cut and notched. I notched the main X braces so that they dovetailed, and started mapping out the rest. And that’s where it ends for today.

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I also spent some time thinking about how to clamp the braces to the front and back. The complication is that all the surfaces are curved, and both the front and back have different radii. Conventional clamping is not really an option. I’m thinking about building my own go-bar deck. I’ll sleep on it, and we’ll have to see what might happen next.

Build day 6: Rosette glued in

Gluing in the perfling for the sound hole rosette was more difficult than I anticipated. The instructions were to dry fit into the channels first – but the fit was so tight that I broke one trying to get it out again. I decided not to sweat too much about it, and figured it would be hard to notice. The other problem was that the outer very thin layer of the perfling was flaking off. In addition, when I spread the glue, I really didn’t have a great way to inject the glue into the narrow channels. The video with the stewmac kit shows using a sort of syringe to do it, but I didn’t have anything like that. So I used a flux brush to push the glue into the channels, and then the butt end of a heavy concrete chisel to push the perfling into the channels. The inner ring, which is completely exposed when the neck is on, did not line up perfectly, but there’s nothing I can do about that now. After getting the rosette installed the best I could, I put some cauls on and applied clamps. Next step will be to start on the braces, but since I’m busy tomorrow night, that will have to wait a few days.

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