Long and Tedious

Really, I got a lot done today honey!!

Today was another productive day in banduristan.  I managed to shape and glue on my "lift" (which I'll get to in a moment), make the bridges and lay out all the drilling to be done - and there's a Ton of it to do.

The String Lift - In Kyiv banduras, there's quite a bit of downforce on the bridge from the strings, particularly the "diatonic row" or приструнки which start low, go up to the top of the bridge and then down do the level of the deck.  Something I do in my Харків instruments is create a "lift" at the bottom of the instrument to take some of the load off of the bridge. Many would argue that this downforce affects the timbre of the instrument and I'm sure it does but, as with any changes, this won't necessarily have a negative effect on the timbre.

Typically, instruments that use a tailpiece type of design, the downforce from the strings keep the bridge in place.  I glue my bridge down so the need for that massive downforce is not necessary and allows me to keep my top and bracing lighter.

One thing about having a domed top is that everything must be arched to match the dome of the top.  Using a spherical dome makes matching that arch much simpler.  In the picture to the right, you can see my 25' domed workboard on my motorized sander.  The "lift" is glued to a piece of larger wood using hot melt adhesive to give a little something more to hold on to.  The lift is 3/8" tall.

I purchased a matched set of a 25' dished workboard and a 25' domed workboard at the same time.  If you search the internet you can find many techniques on how to make your own but in my mind, the $80/board I spent was well worth it when you consider how much time and effort is spent making your own.

Here you can see how I keep track of how much sanding I've done.  I want to lose as little height from the lift as possible.  I draw on the bottom with a white pencil.

Here you can see I've almost made it to the edge

Once sanded to match the domed top, I glued the piece on and used my flush trim bit  to get it right.  There were some mistakes made but I have no intention on going into them now.  Needless to say, good thing I'm building a prototype first!

The reason I needed to get that done was because I need to lay out the шемсток (shemstok) for drilling.  It needs to be drilled prior to being glued to the rim because the holes for the tuning pegs are angled.  If I'm doing a layout, I may as well do everything at once.   To that end, I made the bridges as well.

Below is the setup I use for layout - which I've covered in previous posts.   The rub with this method is it takes a very long time but, it's ultimately flexible.  While it's not suited for serial production, it's very suited toward one offs.  Seeing as I'll only be building one more of this style of instrument, I see little point in making dedicated jigs for this.

Not the greatest shot, but here you can see the шемсток with all the layout marks for drilling.  Next step is to build a fixture to hold it in the proper angle for drilling the tuning peg holes

And finally, here's a shot of the perfectly fitted bridge with the spherical dome.  I found a local source of Bolivian Rosewood so I'm using it for the trim and bridge pieces.

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!