Sunday, January 25, 2009

Neck to Rim gluing, Scroll Carving, doming

I haven't written much lately because I haven't done too much in the shop lately.  I'll be in Chicago most of this week so I decided to post some stuff at least.

Scroll Carving -  A few weeks ago I carved the scroll for the top of the neck.  To fanc
y things up a bit this time I also carved a scroll on the back as well.  The maple isn't too hard to carve except that it splits at the drop of a hat.  I bought a few sharpening accessories for my sharpening gizmo which allowed me to really sharpen up my gouges and that helped a lot. 

After doing a few more things to the neck, rough shaping, chambering to lower weight, I was almost ready to glue the neck to the rim.  First, the rim had to be profiled to the dome shape (see last post).  I used my shop made motorized sanding dish to do the work and it went very quickly.  Surprisingly, the motor is only 1/6hp but it's just strong enough.  I think for this tool it's better to not have too much power so you don't wreck anything too quickly.

What I forgot to do was to glue the pinblock on and profile it before I glued the rim to the neck.  Oh well, that shouldn't be too bad because I should be able to get it really close by hand and then do a final quick sanding of the rim and pinblock already attached to the neck.  Below are a few more picks of what I've done in the last few weeks.  Remember that the final shapes on the neck will be done once it's glued to the rim and further along.  You can also see the jointed (but not sanded) top in the background of one of the shots.   I also included a picture of my first guitar which is just about ready to be level sanded, buffed out, and set up to go.  

I'm off to the airport, hopefully I'll have some time to get some stuff done next weekend.












Sunday, January 11, 2009

Domed Tops

For a long time now, guitar makers have been doming the tops of their instruments using various methods.  The top is domed for several reasons:

A domed top, like an arch, is stronger than a purely flat top with the same dimensions.

Wood expands and contracts due to relative humidity.  If a top is domed and glued at about the lowest level of relative humidity the instrument will see (usually, we don't like to see instruments get any drier than at 40%RH) a domed top can move much more easily than a flat top. That is, as humidity increases and the top increases in width across the grain, the radius of the dome will simply decrease rather than breaking the sides.  If the RH goes down, the top will sink rather than crack. For these reasons, I started to dome my tops with my second bandura but basically, I failed.  

I tried to dome my top by making a dished work board with an arbitrary dish to it.  I basically assumed that the rim of the bandura (the frame) would be level and gouged out a little dome into the workboard, less than an 1/8" at the deepest point.  I then profiled the braces so that they matched the dish of my workboard.

By the time I got everything glued up the little bit of dome I had worked into the design was almost gone because of forcing a dome onto a flat rim and the rest was gone once the instrument was strung up.  The other problem I had was that because the dome was arbitrary, it was very difficult to get the bridge to match up exactly to the top so I used epoxy when gluing to fill the gaps.  Here's the plan for the next instrument.

Hanging out on a lot of guitar maker's forums over the last several years, I learned that many "flat top" guitar makers used a spherically dished workboard to build the dome into their tops.  They use that same workboard to "profile the sides" or shape the sides of the guitar so that they match the 3D aspect of a sphere.  My first two tries at doming had flat rims (i.e. they didn't match the 3D profile of the dome) for this next one, I've purchased a dished work board with a 25' radius.

You can see how guitar makers profile the sides here I used a very similar method when I built my first guitar to learn how to do it except I used a motorized table to make the sanding go faster.  The rims are much thicker on a bandura so I wanted it to be motorized to make the job easier.   I profiled the sides a few days ago and it worked fine.

Next steps:  The next steps coming up will be to glue the neck to the rim, the rim to the back and begin bracing the top.  In my next post, I'll have some pictures of all of the components and how they go together. 


Wednesday, January 7, 2009

Latest Activities

For a while, I was maintaining a website with my bandura activities but for me, the standard html thing was just a little too cumbersome to deal with.  Eventually I'll put some updates there and add some historical info here but for now, to see information about my first two banduras, check the old website here.

Since my last update on that site, I've re-topped bandura number one because the soundboard was too weak and collapsed, completed bandura #3 and almost finished a 000 sized acoustic guitar from a stew-mac kit. I'll cover the details of those in other posts as time permits.  The guitar has been completed and finished (i.e. I've sprayed the lacquer) and the finish now needs to cure for about three weeks before everything is level sanded and buffed to a high gloss shine.  Then the neck is attached to the guitar for finial setup.  While it's curing, I've started work on bandura #4.

After I completed bandura # 1, I decided that I was going to make three banduras in parallel but about 1/4 of the way into the build I changed my mind.  Although it seemed like a good idea at the time, the problem is that you can't use the experience from one instrument to make design changes to the next.  I had made three sets of the main frame parts for the three instruments and as I was going along, I had an idea for a much better way to join the "rim" to the "poly frame" but I had already made the cut on all three parts. At that point I decided that until I get a decent design down, I would work serially instead of in parallel.

Bandura # 4

Bandura #4 starts it's life as the second rim, poly frame and
 neck from that batch of three that I started many years ago.  I changed the design to eliminate that "bad cut" from the original design. This instrument will have one major innovation I'll get to in a minute. The main design elements of this one are:

  • Sitka Spruce Top
  • Sitka Bracing
  • Curly maple Back
  • soft maple poly frame and neck.
The big innovation for me will be that this one wil
l have a spherically domed top using the same tools used by flat top acoustic guitar makers.  I'll go into this more in another post.  As far as I can tell, the Лвівянки (Lviv banduras) have been using this method for a while but this could be the first time that it's been done on a North American Bandura.  I've actually tried to put a dome on my last two banduras and the re-top of bandura #1 but my attempts basically failed.  

I've about had it for writing for tonight and to continue about the doming will take an entire post so to conclude this post, here's a picture I took last night after profiling the sides as a little teaser:










Monday, January 5, 2009

Kickoff

After years of not updating my Bandura Making homepage because I'm just too lazy to learn any of the basic web authoring tools, I've decided to start this Bandura Making blog to document my bandura making progress.  I'll also be using it to voice my thoughts on the state of the bandura community in North America and to a lesser degree, in Ukraine.  Hopefully you'll all find this stuff interesting.