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Hammered Dulcimer design, construction, and unrelated stuff

Saturday, June 15, 2013

Wooden Bicycle


Melanie saw a program from Europe about bicycles made of wood.  She thought it would be cool if I built one, and pestered me enough that I finally started on this.  After drawing the design, I was hooked!  This was a lot of fun to do, and now my head is full of ideas for more.  I was going to call it "Honeydo" because of how she kept at it, but when it was finished, we decided "Re Cycle" would be a better name, because that is what it is, mostly recycled bike stuff.  Melanie being an ex sign painter is designing a logo for it.

The wheels are from a Raleigh 3 speed, these have alloy rims.  Most of the rest of the metal parts are from a 60s Huffy, also a 3 speed, and it had the original twist grip shifter.  The rear drop outs I made from plate steel.  The geometry is taken from the Huffy, and it is comfy old style cruiser.  The saddle is an old Wright's from England which we found for $20.00 at an antique store.  It was really dry, but Neats Foot Oil brought it back to life.  

The way you go about designing something like this is lay it out full size on a sheet of plywood.  First plot all your points; the centers of the wheels, how far apart they are, the center of the crank, and its exact position relative to the wheels.  Then the center lines of the seat tube and head tube.  These are both 71 degrees off horizontal, which is pretty laid back by modern standards, but gives the bike that really comfy, upright feel.  On this bike, these points and center lines are a duplicate of the Huffy, except I moved the rear wheel back an inch.  After plotting the points and center lines, sketch in the frame around them.  I wanted a frame of bent laminations, so I just took a thin piece of wood, and flexed it around the points, then drew around it.  It looked cool right away!  This is the point where you really can see something taking shape, and get excited.  

The main frame is bent lamination of 1/8" Baltic Birch ply, it took about one sheet to do the two pieces 3/4" thick.  I built a frame to do the laminating around, then just clamped the laminations up with glue.  The sheet of Baltic Birch was the only thing I bought for this project except for quite a bit of epoxy.  The rest of the wood was mostly pieces that were laying around the shop.  The laminating was done with Titebond 2, but the rest of the assembly was all done with epoxy.  The holes for the head tube, bottom bracket shell, and seat tube were difficult.  A bicycle is a sort of 3 dimensional sculpture, and everything has to be right in line for it to work, but I got it!  This bike will ride very easily hands free, and that is the test.  After the frame was glued together, I installed a set of wheels and sat on it to see if it was stiff enough because I had my doubts.  The front triangle was too flexible as I had thought, but the rear was good.  So I made the web of 1/4" Baltic Birch ply and glued it in with fillets of epoxy, a standard technique in boat building.  That did the trick, plus gave it a cool look all its own.  Another mistake was the joint between the wood part of the seat tube, and the doughnut for the bottom bracket shell.  It was just butt glued with epoxy, but on the first test ride, it broke.  So I made the large piece you can see to completely surround it and strengthen it.  Next time, the post and doughnut will be one piece.  

As pictured above, the bike is almost finished.  It just needs its logo, one hand grip, and figure out how to get a rear brake mounted.  Other than that, I have been riding it, and it is very comfortable, and lots of fun.  If you want to be anonymous, though, don't ride something like this.  People love to see it.  I have been stopped and photographed.  I've been thinking about carrying a donations jar, and asking for a quarter each time.  Melanie was right, it was a fun thing to do.

Thursday, May 23, 2013

Darkening Cherry With UV Light

At upwards of $12.00 per board foot for the good stuff, Walnut has gotten too expensive.  We used walnut for all our bridges and the rails of the Phoebe hammered dulcimers for 20 years.  Wood prices run in a cycle based on whether dark woods are in style, or light woods.  For the last 20 years, light furniture, light kitchens, pickled woods, white on white were the vogue, so walnut was affordable.  But now the trend has reversed.

So we had to find another wood that could contrast well with the birch top of the Phoebe, as well as sound good.  We had used cherry bridges many times, and it sounds great, but when new is sort of a bland salmon color, but darkens with time to a rich dark red which is beautiful.  Cherry is one of my all time favorite woods.  Trouble is we send out brand new dulcimers, but want them to look nice right away.  The bridges are unfinished, at our price point, a finish is out of the question, so the bridges need to just look good the way they are.

My wood dealer, Mark Hill of Hill Hardwoods in Iowa City, Iowa suggested that I might be able to darken cherry quickly with UV light.  He didn't know the particulars, but I was intrigued.  So I went to the internet, and there wasn't much out there, but lots of folks asking the same question I was.  I did find one mention that UVA was what you needed.

After much searching around, I found that a bug zapper bulb produces UVA.  UVB is what gives you a tan.  UVA is what causes cancer, so this is something to be very careful with.  Don't look at it without  eye protection.

Since the bridges are less than 20 inches long, I bought a 15 watt 18 inch bug zapper bulb on eBay, and got an 18 inch fluorescent fixture at Menard's.  The bulb was $15.00, and the fixture was $10.00.  I built a wood long enough to contain the bridges, mounted the fixture on the lid, and lined the whole thing with aluminum foil to keep the light bouncing around in there.  It works slick!  The lid fits tight, so no light escapes.   3 or 4 days in the box, and cherry gets quite a tan!  They look great on the dulcimers, and the position marks show up nicely.  It really is too cool!

Monday, March 4, 2013

Shellac Finishing Small Parts

I have to thank the guys at Woodsmith on PBS for this great technique.  It needs to be shared with the world.

Since shellac is a universal sealer, and will stick to anything, you can put it right on over wet oil, and it will seal the oil in.  Pretty amazing.  Hand rubbed oil finishes are the deepest and most beautiful, but take a lot of time.  But with shellac in the mix, you can do a complete finish in an hour or so.

First, rub on boiled linseed oil or whatever oil finish you want to use.  Wipe off the excess.  The oil really brings out the color and grain of the wood better than any other finish.  Immediately you can pad on shellac, and it dries right up, and seals the oil in.  Pad on as much shellac as you want to get the gloss you want, or switch to some other top coat, and you're done.  The oil will go ahead and cure under the shellac over the next few days, but you can use your item right away, it is done.  I finished one of my mountain dulcimers in an hour with 1) boiled linseed oil, 2) shellac padded on until I got tired of it, 3) wax.  It looks great!

This technique is the best way to finish dulcimer hammers, or any small item.  The only tools needed are some clean rags.