I'm Back!! Latest Projects

It's been a very long time since my last post!! Although I haven't been posting, I have been working. The last two months have been very slow bandura wise but I did get some work done prior to that, I was just too lazy to post. Below is a picture of six rims I've bent.

From left to right, we have the rims for two Kharkiv style instruments with a slightly modified shape from what I've been doing before, two baby kharkiv style instruments and two Kyiv Style instruments (I'll get to that later). As usual, click on any picture for an enlarged version.


The most interesting things about these rims is the material I used for the rim. In the past, I've laminated three thin pieces of hard maple, roughly 1/8" thick to make my rims. In order to save time and effort, I decided to use a material called "Compwood" Compwood is a regular wood that has been compressed to make it flexible. Once it's dry, it holds its shape.

Below are the forms I used to bend the compwood. I made two forms for Kharkiv banduras, one for baby and one for Kyiv.



Once the wood has been bent to shape, it must be dried. I made a simple kiln from styrofoam board with a small space heater inside. It takes roughly 3 days for the wood to dry.



Below you can see some of the forms and various rims that I made. I used C-clamps to hold the wood to shape while it dried.

So far my impression of the compwood is pretty good although it does have some shortcomings:

Because of the compression process, the wood arrives kind of wavy and such making it rather difficult to resaw. It's also very flexible and bounces a lot during the process. It's quite difficult to get an even cut.

Because it's still quite wet, you can't run it through a power planer because it tears out something awful. The drum sander works quite well but you must again be careful because it bounces so much. My drum sander doesn't have infeed and outfeed tables but that would help tremendously. If I decide to stick with this stuff I may have to add them. Because of the uneven cut, it takes many passes through the sander. I ended up using 3 different grits to get a nice finish on the non-bent pieces.

Over all though, I believe it is less work to use the compwood than it is to laminate.

Current Project: Kyiv Bandura (x2)

Because of some things that have happened in the past, I don't like to build multiple instruments at once. I bent several rims together because it's very efficient but now I'm switching back to serial production.

Anyone who knows me knows that I have little interest in Kyiv Style banduras however, a good friend of mine convinced me to build him one. He's interested in a concert style instrument with re-tune mechanisms. At first I refused because of the magnitude of the project - designing a re-tune mechanism is a huge undertaking - but then I had a though: if I could get a complete retune mechanism from the Lviv factory, it wouldn't be all that hard to do so, I agreed.

Because I've never built a Kyiv instrument, I decided I should build a prototype first before spending a lot of time on a fancy concert instrument. I'm planning on making a few changes to the standard Kyiv / Lviv design to go along with my current philosophies on Bandura design. I'll go into the details in my next entry.

Below you can see the roughly carved neck for the prototype. Initially, I didn't intend on doing a fancy scroll carving on the prototype but since I'm not very good at carving it would be good practice.

Finished at Last!

Here's some pics (click on any picture for a large view):

The neck:

The rosette

And the back:

Over all, it came out pretty well. The top has sagged some under the string tension, but not too much. I might change out the chromatic strings to a lighter gauge, but I'd like to wait a bit first. I think that with some slight modifications to the bracing, I should be able to get the top strong enough to resist the downforce from the string tension and still be loose enough to get a good sound.

Speaking of the sound, you can check out a sample HERE. The sound quality is pretty good, but I'm still trying to figure out how to get a good sound on a solo recording in my living room. The mic I was using sounds like it was boosting the mids a bit. Of course as soon as I hit record I forgot how to play too!!

The highs sound really good and the basses are a nice balance. The mids I'm still deciding whether I like these or the one on bandura # 3 better.

Please drop a note or comment and let me know what you think!

A Sneak Peek!

About 10 more coats and it will be ready to cure. I'll post all of the finishing details at a later date.

I can see the light at the end of the tunnel!!

The end seems to be in sight!  And, although tedious, I've finally figured out how to get all of the pictures to have links to their larger versions.  Click on any pic to get an enlarged view.

I've been working on it quite a bit and here's what she looks like now:

Since my last post I've managed to shape, drill and glue the upper bridge or шемсток, drill for the semi-tones, add the trim piece and riser for the pin block, shape and drill the bridges, glue in the structural bracing and glue on the "fingerboard" (which isn't really a finger board).  Here's some of the details:

Shaping the bridge is not very challenging, but drilling for the holes is.  The first step is to align the bridge in the position it's going to be when it's completed.  Using my domed sanding disc, the fit between the bridge and the top was great:

Once in position, I use a laser level and some graph paper with 6mm spacing to lay out each string.  I found the graph paper on a site here .  My setup looks something like this:

Here's a close-up of how I use the laser to mark the holes for each string. I line up the laser with the correct hole in the upper bridge, then the graph paper, then make a mark on the bridge.  To align the graph paper, I use a ruler to extend the line of the neck so that the bass strings will be parallel to the treble strings.

While I'm at it I mark the locations of the tuning pegs and semi-tone strings.  Unlike the main row of strings, It's very difficult to mark their locations using a template.  Once marked, I use an awl to start each hole. this setup to drill the holes at the correct angle. If you look, you'll see that I use surgical loupes to get a better view.

Unfortunately, I screwed up the first bridge and had to re-do it.  Once everything is drilled, I can drill two pilot holes in each bridge to hold them in position for temporary work and for final gluing. In this next shot, you can see the little wires with a hook on the end sticking out of the bridge.  I've also attached the template to mark for the tuning peg holes.

Finally, here's a picture of the inside of the instrument with the structural braces glued in.

To drill the holes for the semi-tone strings which go into the wood at a weird angle, I use a jig of my own design below.  I later learned that surgeons have been using a similar jig for ACL reconstruction...go figure.

At this point, there's not much construction left, mostly final shaping and finishing.  Stay tuned!

Top is on, Moving forward

Qestion to all - for some reason, when I upload pictures, on some of them you can click and it will zoom in, and on others it doesn't work.  Obviously this is some sort of software quirk but if anyone knows how to avoid it, please let me know.

No, it's not that I haven't been building, it's that I haven't been writing.  I have been a bit busier at work lately so that has slowed things down.   If all goes well, this instrument should be ready in about a month.

The Top is on and is holding it's dome wonderfully !! 

You can see in the picture above, I've got a 25' radius template in front of a steel ruler.  The top is holding the dome very well and I'm hoping that this will fix the issues I've had with the tops collapsing on to the internal bracing - I guess we'll see.

In the picture below, you can see the trim piece that sits below the пів тони or half tone (the black keys).  The thing I didn't think of when I was designing this is that with the top domed, the "nut" end of the strings (the top) would be sitting on a spherical surface, not a flat one.  To fix this, I sanded the domed profile into this trim piece to bring the half tone strings back into level.  The 25' sanding dome worked perfectly for this.  If you look carefully you can see how the trim piece gets thinner at the center and thicker at the ends.  The wood is East Indian Rosewood although it looks much redder than typical EIR.  I bought it off of E-bay so who knows?

In this next picture you can see a test piece I made to check out the bridge fit to the top.  The test piece isn't perfect but I've made changes that will fix that and should yield a perfect fit.

Now here's a pic of the actual bridge blank of EIR pre shaping - notice the gaps.  The final height will be much lower but I wanted extra material in case I made mistakes EIR is rather expensive.

Well, that's all for today folks.  I promise to write more often in the future

The top is braced

This weekend I had some time to brace the top.  Here are a couple of shots:

this is a small deviation from how I normally brace the tops, namely that I added a cross grain brace to help support the dome in the top. That brace is capped with carbon fiber to give it additional strength because it's so short.  The height of the brace is such because there are additional structural braces inside the bandura that run vertically to resist the pull of the strings.  A tall brace will interfere with these braces.  I recently posted some questions to the OLF regarding some bracing ideas and that discussion can be found here.

Some specs from this top:

Weight before bracing: 278g

Weight after bracing (not final): 368g

Thickness: ~0.128"

Guitar makers will notice that this top is almost double what a guitar top weighs.  Considering the additional load that a bandura top takes it's not surprising.  Tapping produces a decent tone but nothing like what you hear when tapping a guitar top.  Unfortunately, I'm not sure that anything can be done about this because of the huge load on the bridge from all of the strings.  The good news is that this won't necessarily mean that the sound will be bad.  My prior instruments have bracing that's just as heavy or heavier than this one and sound pretty good.

A busy day in Banduristan

It's been a while since I've posted because I haven't had a chance to work on anything for quite a while.  Fortunately, this weekend I managed to get a lot done.

Rosette

Doing the rosette was basically holding up the rest of the build.  The pattern is rather complicated to do and took me almost all day Saturday.  There are a few flubs in the fine lines around the abalone but the materials are so expensive I decided to try and fix it as best I could and move on.  As it is, the mistakes are visible under close inspection but it looks fine from two or three feet away.

I used a precision adjustable router base to cut the ring-slots. 

The wood ring is a piece of koa I brought back from Hawaii back in 2000.  A tip I got from the OLF was to inlay the wooden ring first, then cut the slots for the purfling and abalone.  For the abalone, I used a new product called Zip-Flex which made life much easier.

As it was, inlaying the black-white-black was very difficult and is where the flubs are.  I tried to use a scarf joint:

to make it look seamless but it didn't work out so well.  The problem was that I only cut the angle on one end and tried to bend the other end up along the angle but it didn't follow closely enough.  Next time I'll do a true scarf joint which should work better - it worked perfectly on the abalone strips!

Braces

With the rosette done, I could move on to the braces.  Here you can see the four almost finished braces.  Because the braces are so big, I cut out the centers to form sort of an 'I' beam to lighten them up a bit.  I dropped the weight by about 25% by doing so.  You can also see the 'secret weapon' which is the small brace with the black top.  The black stuff is a strip of carbon fiber glued to the brace to help strengthen it. This short brace will be glued at 90 degrees to the grain of the wood and I'm hoping that this will hold the dome and keep the string tension from collapsing the top.  I'm a little concerned that this brace will make the top too stiff but I'm hoping that the top not collapsing will make up for the extra weight.  When checking tap tones of guitar tops vs. bandura tops, the guitar top has a much higher pitch which implies that guitar tops are much stiffer than bandura tops yet guitars have a much better bass response.

In this shot, you can see the dome shaped into the braces.  

Here you can see the layout of the braces.  The 'I' beam braces go up and down and the carbon capped brace goes diagonally.

Finally, I also managed to complete most of the body and glued up the шемсток or 'upper bridge'.