Went and got inspired by my brother's instrument-making, so I'm going to try make a bodhran. Then I'll have to learn to play it well enough to not make a complete fool of myself and annoy everyone else, and maybe in a few years I can actually join in some sessions...
The first attempt was going to be by bending Baltic birch aviation plywood into a web clamp, crank it into a circle, and laminate 3-4 layers together. My roommate had some left over from another project, so he ripped a bunch of 4"x4' strips. That would make for about a 14" diameter bodhran, which is a bit small. Unfortunately, the plywood was not bendy enough for that, even after soaking in water. I have heard that glycerin might help, and would be readily available at a pharmacy.
In the meantime, however, I was in Lee Valley, and they had off-cuts of cherry veneer for $3 per pound (approx 15 sq ft.) So I bought about 3 pounds of that in various sizes and shapes, and will build up my own plywood. There's three pieces of the 4-foot size (all they had left in longer pieces), and about 30 or 40 of the smaller ones. The long bits have a few splits in the ends, but hopefully I can cut a couple of strips for the first and last layer. The stuff is quite flimsy, so I think I'm going to need a pretty darned solid form around which to build it.
First step in making a form was making a jig for my jigsaw. Which has an attachment for a ripping fence, so all it needed was a 1/2" by 1/16" strip of metal with a hole in one end. Turns out hardware stores don't carry anything that small, but I found a piece of brass that would work at a hobby store. On my first try cutting circles out of plywood, the blade kept either tracking too straight (not really a problem, just back off and shave a bit off on a second pass), or digging into the circle (making it less perfectly round...) I figured it might be because the spines on my blades were worn and rounded, so they easily hopped out of the guide. New blades (and a specific narrow scrolling blade) fixed that problem, and I got my almost-round bits of plywood cut out. I'll re-trim them to a 17 1/2" diameter later. In the meantime, I chopped up a couple of two-by-fours, and coming from the school of overbuilding, plus being in the school of not owning many clamps, I glued and screwed the two-by four chunks to each plywood circle. These I'll also trim down, then glue the two halves together and hopefully have a nice round form.
That is, if the jigsaw co-operates. This is one of the 2x4 chunks I cut, admittedly with the rough-cutting jigsaw blade and going rather fast. It entered the wood nice and square like so...
...but exited at a seriously not-square sort of angle. Hopefully this was merely because of going fast, because the special narrow scrolling blade will not be long enoug to trim the two-by-four-plywood laminates above into round, so I'll pretty much have to use the blades that did this. I'm hoping that if I cut it a bit proud first, then trim it down a bit at a time, there won't be enough wood on the outside of the cut to put any inward pressure on the blade, but I dunno if that's the way the world works.
Also, just for fun, a picture of the roughed-out cross-bars for the back of the drum. I'll work on sanding these some more while the glue dries on the form. I think a lot of bodhrans don't even use cross pieces anymore, but I feel like putting them in. It would probably have been *way* easier to round the wood first, then join the centre, and fill the gaps with plastic wood. But that wouldn't me any fun, now would it? Not sure yet how I'll attach them, but I can burn that bridge when I get to it...
So the photos above are with my roommate's digital camera. I took a few snaps with the camera in my free-with-contract camera phone, and then inquired about how exactly one would get those off the phone and onto, say, a computer. Apparently, this requires a $30 cable and a $40 software package. That seemed rather silly, so I borrowed my roommate's camera instead. Then today I found a $99 camera at Office Depot, so I picked that up. Now I can bore y'all with far more pictures than you wanted to see... This is starting to trim the forms. The jigsaw's baseplate isn't very well supported here...
...so I attached a spare bit of two-by-four to a scrap from the plywood; this can now be clamped to the workbench to provide support for more of the jigsaw and help it avoid going quite so wonky.
First pass on the first half of the form. Halfway through the first pass on the second half of the form, the blade started hopping out of the jigsaw. Stupid quick-release clamping system. That's the second blade in as many days that's started doing that, and it seems once they pop out once, the spine looks a bit worn and they won't stay in at all for love or money... So it's off to the hardware store to buy a few more blades. Good thing they're only a buck each.
Decided that the jigsaw is most definitely not a precision instrument, and rethought the form a bit. Knocked all the wood off the two plywood circles, then cut some fresh bits and screwed them all together like so...
...then stapled a section of aluminum flashing around it to avoid a massive gap that the veneer could get pulled into. Though maybe it's not even needed. Perhaps the round shape would be stable enough and the veneer stiff enough once bent into a circle along one axis to not buckle along another.
Also not sure if this is necessary, but covered the form with three layers of newsprint strips and one of saran wrap, in hopes of being able to slide the finished hoop off more easily.
Then I layed up the first layer of veneer out of two strips cut from the long pieces. I think if I were doing this again, I would first glue a foot overlap between two four-foot sections, and then fit that around the form and glue the other overlap once the first was dry. Fitting two long sections of glue-covered veneer around this thing was rather a challenge, and I'm not sure that there aren't some air-gaps created by trying to force it rather than having it lie nicely. Oh, well, we shall see if this works, at all.
Looks like this did not really work. The veneer all softened and bubbled up between the wraps of tubing...
...and I don't think I had laid the first layer quite straight, so there's a bit of a gap here, too. I figured this was the more serious problem, because if the first layer's a bit conical rather than strictly cylindrical, I'll never end up getting a good strong lay-up, becase each layer will bubble up *somewhere*. So, back to the drawing board. To solve this problem, I started afresh by taping a long strip of paper to the form, making sure it was on straight and square. Then I started gluing wood bits to the paper, lining each piece up with the edge of the paper, which should in theory be a straight line. I'll sand the paper off the inside when I'm done.
Then I got another 2-ft piece of aluminum, covered one side with saran wrap for release-y goodness (not sure how well wood glue would bond wood to aluminum, but it seems to bond very poorly to saran wrap... I also picked up a few spring clamps to hold the metal (complete with its sharp edges) in place while wrapping the latex tubing around it. Unfortunately, that tends to lead to the tubing snaking its way around the clamps and a few curse words. Once Glenn moves his boxes out of the way, I'll stick a workmate in a corner of the living room and fashion some way of clamping the form into that, so it doesn't rotate while trying to pull the tube tight, and I'll have a hand to spare for untangling :)
I think this is working better. Less warping, at least. I'm getting a bit of a gap here, rather than a tight butting together of the different bits of veneer, but I figure I can just fill those up with glue as I put the next layer down.
Sort of like so... And even if the rim ends up with a few voids, I do not believe it really makes any difference to the sound (except maybe when doing rimshots...) so as long as it's strong enough to hold the skin tight, it may not matter.
Gluing up the next layer
The veneer really curls up once you spread the glue out. I doubt there'll be any photogenic updates for a while now. It'll be about 45 repetitions of the last five pictures, probably letting it set for at least a few hours between each one. So maybe three or four weeks :) Then we'll take it off the form and see what it looks like. Gulp.
Hmmm. The veneer with grain going across the rim seems to hav buckled up something fierce.
I wonder how strong corrugated plywood is? I also wonder whether I can override the default focussing behaviour on the camera, because I didn't really want to focus on the newspaper in the background, so much....
I'll try wetting the old layer down before putting down another layer with grain going around the rim.
Clamping the form into a workmate helps a lot with getting the tubing wrapped tight. Dunno if it's tight enough to flatten the corrugated layer, though. Dunno if I need to worry about it. This is still an inner layer that won't even touch the skin, so if it adds some tack-hiding thickness to the rim, that might even be a good thing. I'll need to decide whether to put more cross-grain layers down, or whether this warping will reduce strength more than having crossed grains will improve it. I'm tending to think not. But maybe I'll attempt one more cross-grain layer, wetting the wood thoroughly before gluing it up. If it lies flat, great, and if not, I'll add enough along-rim layers to form the skin-contacting parts of the rim and chalk these up to hiding the tacks :)
No photos of about six weeks worth of putting another piece of veneer on every couple of days... And then I started building a canoe, so the bodhran project got back-burnered for a while.
Epoxy on the canoe was still a bit too green to sand, so I finally re-visited the bodhran project. Popped the form out, and the frame seems rigid enough for government work.
Swedish slojd drawknife from Lee Valley worked awesome for trimming off all the edges of the veneer layers. So far, I pretty much got them trimmed down to the lowest denominator. I guess the next step is to try to approach some reasonable facsimile of flatness, and if I were to be ambitious, squareness...
Wool pants are warm, but maybe not the best attire for carving? Also, those layers with the grain running across the hoop, which all buckled, are still looking pretty corrugated. I'm sure Lloyd's of London would laugh at the number of voids in the plywood, but it should work fine for this purpose... Nothing epoxy and woodflour can't fix, though, assuming I have a few ounces of epoxy left when the boat's done :)
The inside layer also isn't particularly flat. The paper I put down as a first layer works as a nice reference for sanding though. A fair bit more sanding to do, but there's a limit to how many hours in a stretch sanding remains fun for, and it's not very high.
Hey, look at that. The crosspieces even fit and everything. Actually, they fit kinda loose on one side, and kinda tight on the other, so I'm guessing the frame's a bit cone-shaped rather than a perfect cylinder. But perfection is highly overrated, anyway.