Sunday, August 7, 2016

Day 127: Fish Glue and Trenails

Once again, there's been so much happening at Tortuga Early Instruments Worldwide Headquarters I've no had time to post. Time to remedy the situation. First, I want to wrap up one of my mistakes so we can move on. The photo below illustrates my faulty nameboard center window cut.

As I said on Facebook, I'd like more of whatever I was on when I made this cut. Not only is it off, all three of the windows are of insufficient height. Okay, in my defense, it was one of the first things I worked on after completing the keyboard. Yeah, I know, lame. Regardless, I'm going to need to work on all three windows, but, at Owen Daly's (of Owen Daly Early Keyboard Instruments) suggestion, I'll be waiting until later to clean them up.

Random Roger Green also asked the salient question, "Aren't you veneering it? If you are, why not fix the holes and just put another layer of [astonishingly thin] veneer over it?" Once again, Owen and Roger have shown me the way - and the way is down the road weeks or months from now. Okay, enough with the mistakes, let's look at a few things done right.

First, I finished up gluing the remediated upper belly rail (UBR). You can see in the photo below where I created some small clamping blocks covered with blue painter's tape. This prevented the blocks from being glued to the case, and I used the blocks to keep the clamps from marking the wood during glue-up.

All measurements are good, everything is square and all dados and parts line up where they should. Now that I've fixed all of the mistakes I baked into the UBR, I'm proud to say I've instituted a new cutting program at Tortuga Early Instruments Worldwide Headquarters. When cutting the parts and pieces below, I literally wrote the dimensions on the wood with checkboxes to ensure I made the correct cuts. The first parts cut using the new program were the lower braces. Before I cut the pieces, though, I had to mark out the upper and then lower brace lines onto the case sides.

Upper Brace Lines

Lower Brace Lines

Once I lined everthing out, I carefully proceeded with the cutting and shaping of the lower braces.

I cut all to dimension and drew on the cut lines of the curves. The idea is the have a 1 1/2" bar with two inches of a full three inches in width at each end. You can see in the photo above that I once again used the trusty, old magnetic screw dish to make my angles.

I then cut the pieces on the band saw (sorry about the poor quality of the photographs - I broke my cell phone and have not yet replaced it, relying, instead, on my little Samsung tablet's camera and it sucks) and shaped them on the Ridgid oscillating spindle sander. I know, I have kind of a Darth van Beethoven thing going on there. I don't care - it's safety first at Tortuga Early Instruments Worldwide Headquarters!

As you can see in the bottom photo above, I left a little leg room on each end as suggested by Mr. Miller in his eBook Most Excellent. The longest one requires angle cuts on both ends and all the others have them only on one end, yet it's been my experience that these things are best left a bit rich because it's frankly kinda hard to cut an angle perfectly on the table saw the first time. I did, though, get them all cut and put in for a quick dry fit.

All was well, so I went ahead and glued and clamped them in.

As you can see in the bottom photo above, it looks exactly like the dry fit except that they're glued in. I suppose this one's for the record. You'll also notice gaps where there shouldn't be gaps. I should have sanded the bentside ends of the braces down to fit the odd bentside angle. The bentside continues to offer opportunities for improvement and I certainly will be addressing this in future builds by making another lamination form or simply bending a 1/2" plank. We'll see.

Once I was satisfied with the glue-up, I pounded two trenails (pronounced "trunnels") into both sides of each brace. I made my own using red oak and gave them a dull point using a bench hook and 1/2" chisel.

A trenail is really just a square peg pounded into a round hole. In many ways, this is a great metaphor for my life, but I digress. In the end, Owen was right - there's something really quite satisfying about pounding them in, especially the "THUNK" when they hit home.

These will hold the braces fast and will be completely covered when I veneer the sides. Yes, I'll cut them off and clean them up. Sheesh.

On a couple of completely unrelated notes, I experimented with fish glue this past weekend. Now, the stories from my luthier pals about fish glue are as varied as they are interesting. As I always say, "Ask five luthiers for their opinions on a build method and you'll get seven answers." This was the case with the fish glue. Mark Roberts of Mark Roberts Guitars and Ukuleles gave me a small bottle, so I experimented with it a bit.

Conventional wisdom among my fellow builders is that fish glue is for temporary use only, when one requires a weak joint. When would a luthier require a weak joint? Well, some builders glue blocks to parts such as case sides, use them to clamp during glue-up, and then remove them with heat. This requires an ostensibly weak glue such as fish or watered down hide.

On the other hand, Mark tells me a story from a luthier pal of his who built a guitar using only fish glue that has traveled on six continents in just about every weather condition imaginable for the last 20 years and it's still as solid as the day it was built (or the fish glue dried, as it were). The photo above illustrates a two-day test I ran on a couple of pieces of scrap using the fish glue he supplied. I cannot get them apart. I even tried cold, room temp, and hot water.

Tomorrow, I'll hit it with the heat gun to see what happens. I can say with confidence the glue is incredibly easy to work with during glue-up; it cleans up quickly using hot water and a paper towel and washed easily off my hands. I suspect the fact that this glue is made from fish air bladders, rather than bones and/or cartilage, makes a difference, as would its final formulation by the manufacturer. More to come on this interesting, sticky new twist.

I also made a couple of little racks to get some of my clamps off of benches, shelves, and other hangy-thingies and up out of the way while remaining easily accessible. My solution:

Yeah, I know it's trivial in the grand scheme, but, sometimes, it's the little things that count.

Until next time...

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