Hammered Dulcimer design, construction, and unrelated stuff

Thursday, June 30, 2011

Avenir AC3 bike computer programming

I have an old Avenir AC3 bike computer from 2000 for which I had to change the battery. Of course it forgot everything it knew, and needed reprogramming. And the manual was long gone. In searching the web I found nothing but misinformation, so just sat down and started fiddling with it. After 45 minutes of frustration, I finally put 2 and 2 together, so here it is. Hope this helps some one else.

My computer has 2 buttons. press the right one until you get to the screen that has the ODO reading. Then press and hold down the right button until it changes to a different screen, and the M/h (or KM/h) icon is flashing. You can then use the left button to choose which of these you want M/h is miles per hour, and KM/h is kilometers per hour. Press the right button, and the last digit of the 4 digit number below is now flashing. This 4 digit number is very important, and is how you set your computer to know what size tire you are using, and is THE CIRCUMFERENCE OF THE TIRE IN MILLIMETERS. You can find this in 2 different ways. You can measure the exact height of the tire fully inflated in MM, and multiply that by 3.1416 (pi), or you can do as I did, and put a metric tape measure on the ground, make a mark on the tire, then roll it 1 revolution next to the tape then see where it came to. My recumbent has a 20" front tire, and the measurement happened to come out to 1527mm. You can set this number one digit at a time on the ODO screen. Keep pressing the right button, and eventually you will get to the actual odometer reading. You don't have to change that if you want. The next press will bring you back to the normal screens. You can set the clock in a similar fashion. Get to the clock screen, then press and hold the right button until the time starts flashing, then set it with the left button. If you want to erase the trip information, and start a new trip log, get to the ATM screen (this is the time elapsed) then press and hold the right button, and press and hold the left button. The number will go to zero, and also DST (distance traveled) number on the next screen will go to zero as well as the AVS (average speed) number on the next screen. The odometer reading will remain unchanged.

Hope this helps somebody else. If you have one of these, don't throw it away just because you lost the manual. It is really a nice computer and very accurate once you get it properly set. If this has helped you, please write me, and let me know. Chris Foss songbirdhd@iowatelecom.net

Friday, June 3, 2011

Wood selections

For many years we built the Whippoorwill and Warbler dulcimers with solid Honduras Mahogany tops. We were buying it from some folks in St. Louis that imported it directly. Otherwise known as "Genuine" Mahogany, it was a truly great tone wood. But in the very late 1990s an international ban was put in place on trade of Honduras Mahogany taken from its native range. By 2007 the supply of it had dwindled to the point that it became unavailable for most purposes. Even the big guitar companies that have depended on it historically can't get it, and all of us as instrument builders have scrambled to find substitutes.

There are several African woods that are now in use and called mahogany. They may look similar, but none are as good. They are harder to work, not as stable, and won't sound quite the same. The most prevalent is Sapele. It is the right color, and all of it that is imported is quartersawn because it has to be to remain stable. It has a striped look to it because the grain is constantly changing directions, and it gives it a shimmer under a finish that can be very pretty. Another wood is Khaya, which is slightly darker and more dense. Just beautiful under a finish, but too dense for hammered dulcimers.

We decided since Genuine Mahogany was no longer available that we should quit using tropical hardwoods altogether. A lot of wonderful wood grows right here in the USA, and it is all sustainable. In fact, American forests have increased in volume of board feet every year since 1911! So for us it was a matter of figuring out which woods to use. After trying several different woods, we settled on Cherry for our Whippoorwill and Warbler models, and a surprise; Poplar for the at the time new model Wood Thrush. We tried Quartersawn Walnut which is a great tone wood, but couldn't find a source for it. The best Walnut in the world grows right here in Iowa, but nobody cuts it quartersawn which would be necessary for stability of a piece as large as a dulcimer top. We would occasionally find a few quartersawn boards in a randomsawn pile, but couldn't get our supplier to sort out the stuff for us we'd need.

No matter, Cherry turned out to be just great. Here's where experience as a woodworker comes in. The Forest Products Lab publishes tables of data on various woods and their properties. They have shrinkage tables on all the major woods, but their figures are for percent shrinkage from green to oven dry. This is good for a general idea, but the figures we really want are percent shrinkage from 12% to 6% moisture which is the range a kiln dried board will go through in a normal year. There aren't any figures like that out there anywhere. You just have to know what works, and what doesn't. According to the FPL figures, Douglas Fir ought to be good, and we made some dulcimers from it. But it moved a scary amount within our range, a 20" wide board would shrink 1/2"! According to the FPL numbers Cherry should not work for us, but it does! It is wonderful, and within our 6% to 12% range of moisture seems totally stable. A very worthy substitute for Genuine Mahogany indeed! And it sounds great. And best of all it grows right here in Iowa. There is a producing mill 3 miles from our house, and they do a wonderful job with their saw mill and kiln. Absolute quality. I buy most of the lumber we use from them, and feel good that it is locally grown, locally milled, and used locally.

I believe that the market was used to Mahogany dulcimers, and still wanted them. Don't blame them, the old stuff was great. But Sapele and others are not the same, and we as consumers should not demand it. We are contributing to the cutting down of the tropical rain forests. If we ask for products made from American woods, we are contributing to our own economy and the use of sustainably produced local woods. This in turn enhances the value of our forests. They are a treasure.