Finished!

Well,  it's finally ready.  Here's a few pics:

And one of the back:

The шемсток or "shemstok":

Overall, the sound is pretty good.  Basses are very strong as are the mids.  The highs lack a little sparkle that I have on my other instruments but I think it's because the bridge is a bit too heavy - something that'll be easy to solve in the next instrument.

Drilling & Finishing

For the four people actually following this blog, I apologize that I haven't been updating this blog. I have been working on this bandura, but my day job has been extremely busy as well so it's been difficult to find time to build and post. As you can see from the pic, she's nearly done.  But back to what I've been doing for the last 3 months:


Shemstok - drilling for tuning pegs:

To angle the pegs back which is typical of the Kyiv bandura, drilling for tuning pegs requires a compound angle - to handle this, I made an angled table that allows me to drill the holes on the drill press.  It's essential to use a drill press for this operation because if the holes are even a little bit too big, the peg won't hold.  

At this time, I also drilled the holes for the Підставки or "Pidstavky" which would be the equivalent to a "string nut" on a harp.  These holes are vertical so they don't require an angled table to drill the holes.

Gluing the Shemstok to the Frame:

Once all the hole drilling was complete it was time to glue the shemstok to the frame.  For this operation, I used West Systems Epoxy.  This is probably the most stressed joint in a bandura and it's got to hold forever.

In this process, I found that the sled I built for binding is very useful for holding the bandura off the work bench to fit the clamps underneath.

Unfortunately, even after all that messing around with the templates etc, I'm still not 100% satisfied with the tightness of the joint between the Shemstok and the Frame.  Normally, for this joint I'd pick a polyurethane glue but I chose epoxy because it has strength when filling gaps, unlike other glues. The down side is that it is heat sensitive and will release if it gets too hot.

As a little insurance, I ran some screws through the frame into the shemstok to make sure it stays where it's supposed to.  The trick is though that in the final instrument (the one with mechanisms. It will be impossible to do so because the mechanism lives where the screws are right now.  I'll have to be extra diligent when fitting for the next instrument to ensure that this joint is really tight and will hold.

Here's a final picture of the insides before the back is glued on.

One more step before the back goes on: the ball end of the string is held at the bottom of the instrument.  To give it a place to "hide", I routed a slot in the bottom of the instrument using the tool to the left.

The plastic pieces ride on the frame and the wooden block keeps the slot an even distance from the edge of the frame.

Here's the completed slot.  Once complete, there were two things I didn't like.

First, the slot is a weak point in the frame.  There is internal reinforcement but it doesn't extend much past the point of the slot.  For the next instrument, I might add a 1/4" or so to the internal brace to give it a little more backing. 

Second, I should have made three "stops" in the slot. i.e. instead of a continuous slot, there would be two places where the slot stops, and re-starts after about a 1/4".  That might not make much of a difference structurally but it would certainly help me sleep at night.

The next step was to drill holes from the string lift to the slot where I used the same tool I used on my last bandura to drill the string holes in the shemstok. 

And here's a picture of the back being glued on.  I used Titebond Original glue for this procedure.  

Unfortunately, I forgot to take pictures of the back bracing on this one.

Once the back was on I used a 1/2" round over bit in the router to ease the edge on the back.

In my prior instruments, I had an extra piece of frame I called the "poly frame" for Polyganal frame to add extra material to the back of the instrument to allow a 1" radius on the back for comfort.  That frame adds a lot of work and I think, not much benefit.

My client requested that type of construction for his premium instrument which I'll do but, I'll almost certainly not use it in the future.

The Bridge

The bridge was actually started a few months ago and you can see it in the pictures in the last post when I was laying out the strings. I'll cover the details now though.

For this instrument, I purchased a piece of Bolivian Rosewood for the bridges and various trim pieces.  The bridge is cut on the bandsaw to rough shape and then sanded to final shape on my oscillating spindle sander which can be seen in the background of a few of my pictures.

It's then on to the router table to cut two ledges, one on top and one on the bottom, using a rabbeting bit.  I make the bridge intentionally tall at this point because a lot of the middle will be removed on the domed sanding plate like when I was fitting the "string lift".  

With the ledges cut, I use this homemade tool to cut a slot for the wire which will serve as a saddle.  The slot is cut on the top and bottom.

Once the slot is cut, it's time to move on to drilling the holes for the strings.  The locations for the strings were laid out at the same time as the locations for the tuning pegs and Pidstavky.

Like most things on a bandura this step also involves complex angles etc.  In the picture to the left you can see that the hole through the bridge has an angle - this is to create down force on the saddle and to mute the "dead length" of the string.   The приструнки or "white strings" need a down angle and the півтони or "black strings" need an up angle. 

In addition to that, the the holes must be drilled parallel to the direction the strings will be running on the instrument (duh) which requires yet another fixture.

Here you can see that fixture.  Each style of bandura requires its own fixture to make sure the strings are "straight up and down"  For my Kharkiv instruments, I built the break angle in  to bridge holder but since I need to make opposite angles for the different strings.  I did not build the angle into the fixtrue but instead decided to upgrade the angle table I built for the shemstok operation to be adjustable.

Here's a picture of the revised adjustable angle table.  I found the hardware at Rockler Woodworking and although it's not the greatest, it's good enough for this job.

And here's a shot of me drilling a string hole in the bridge.  You can see I'm wearing loups so that I can get the hole lined up perfectly.

Because the drill bit is so small, it can tend to wander (flex) when drilling.  I used an awl to put a divot at the start point of each string and then carefully align the bridge under the drill bit to minimize the wandering effect.

The bass bridge construction is similar but easier because it's not curved like the treble bridge.

With all of this completed, it's time for finishing.

Finishing!

With all of the construction complete, it's time for finishing.  I used basically the same finishing schedule as I did with the guitar and bandura # 4 so I'll keep this part kind of brief.  Because this was the first time I've built this style of instrument, it came out a little sloppier than normal so step one was to fill in any little gaps with wood filler of some sort.  To help hide the mistakes, I decided to do sun burst finish on this one just like the last instrument.

The back is made from the same piece of fiddleback maple as the last instrument and while the last instrument looked good, the figure of the maple wasn't "popped" to my satisfaction.  To help bring it out, I used an old trick where you stain the figured wood with a dark stain then sand it back to bare wood.  The figured grain absorbs the stain more than the non figured and it really pops the figure well.

The whole instrument is now sanded to 220g using 100g in some areas first that need a lot of sanding.  I used Koa for the rosette and that needed some pore filling as well.  I didn't mention it but I filled the pores with epoxy at the same time that I was gluing on the shemstok as there was plenty left over.  It was at this time I learned that the "compwood" I used for the frame had cupped a bit which required a lot of extra sanding. Once sanded, the entire instrument gets a wash coat of super blond shellac.

For the sunburst, the body first gets a coat of amber. I mix the amber dye in with the finish (Target USL, just like last time) and here's a shot of the instrument after the amber coats.  I think you can really see how the dark staining & sand back brings out the figure of the maple.  It really makes me want to build an instrument that's "clean" enough to finish without a sunburst.

Next, I used an Iwata Eclipse airbrush to add the black parts of the burst.  For this, I used an opaque black pigment mixed with the USL.

And then we finish the burst with transparent red. The bursting took about two days to allow the various coats to dry.  To help minimize mistakes, I use pretty mild color mix that takes a long time to build a dark color.  That way you can't make drastic mistakes in the finishing.

Once the burst was complete, it was about another 18 coats of clear.  Now the instrument needs at least two weeks for the finish to cure. While the finish was curing I made the Підставки  or "String Nuts".

I purchased a few rods of 3/16" aluminum for the string nuts then sanded them with 220g so they looked nice and polished them up a bit with some nevrdull. The Pidstavky need to be very accurately cut to length so I made a jig to cut them on the table saw.  The picture on the left shows how it works.

And here's another shot.  The toggle clamp holds the pidstavka securely so it doesn't go shooting straight in my eye.  The rod to the right is the length stop to ensure that they're all the same length.  To get the correct length, I strung up two strings a while back and determined that the short ones needed to be .4" shorter than the long ones to get the string crossover in the correct location.  For this first round, I made the long ones 1.1" and the short ones .7".  If that's too long, I can always cut them all down to around 1".

So yesterday I spent about 5 hours sanding the finish starting with a light sanding with 400g paper on a large felt block followed by a sanding with 600g and then 800g.  Some areas like the scroll won't be sanded too much because it's really easy to sand through the finish and when you do sand through an area that's dark with a light wood underneath, it's quite obvious.

I bought a new coarse buffing compound for my buffer so I'm hoping I can stop at 800g and will be running a test later today.  If not, it's just means that I've got to go to 1000g with an Abralon pad on my random orbit sander.

Once the finish is fully buffed, the bridges need to be glued on and the instrument strung up - hopefully that will be done by the end of the week!

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.

Starting to look like a bandura - I managed to have several good evenings of work and have gotten to the point below (note to Yuri P. - those are not the bridges I'll be using and are there just for the photo!). Soundboard is glued on, shemstok is fitted and the instrument is bound and purfled. Fitting the shemstok to the curve on the top of the bandura was a nightmare and I do not look forward to doing it again but, here's the steps necessary.

Template Routing - This is a trick I remembered from my non-luthier woodworking days. Basically, using a router with offset collars, you can make two objects which fit together. I made a template from the shemstok (upper string holding thingy) that I'll be using on the next instrument (purchased from the Lviv Factory). I then vary carefully made a second template of the curve I'm fitting using a 1/2" flush trim bit that ends up 1/2" under sized. With that template carefully aligned and using a 1.5" diameter collar (providing a 3/4" offset to make up for the 1/2" offset plus 1/4" radius of the bit) with a 1/2" diameter bit, you can cut a perfect mating surface.

In the shot below, you can see the template on the bandura. What's not in this shot is an alignment template screwed on top used to position the 1/2" under template. The alignment template is nothing more than a "practice run" to make sure everything's o.k. I left it screwed on so that I could properly align the real template. The goal in alignment is to remove as little material as possible and still get a good fit.

It should be mentioned that the template is very hard to position on the top, even with the alignment template because the top is not flat remember. I had to make several tapered shims to get the template to sit 90 degrees to the edge and still be solid.

Here is a picture of the router with the 1.5" offset collar and a router bit.
And finally below is a picture of the material removed. It may seem like nothing but it's essential to have a perfect fit not only for the glue to hold, but so that it looks good too. Because of the shape, I ended up hand fitting the very end of the shemstok because to do otherwise would have required removing a ton of material from the rim.

And here's a shot with the shemstok clamped into position - perfect fit!


Actually there is a small gap near the neck and a small gap on the back side in one spot. Neither should be structurally significant and I should be able to hide them. The next step is binding and purfling.

Binding Channels - Bindings serve two purposes - they hide the end grain of the top and also provide sort of a bumper to protect against mild hits. I think that mostly it's an esthetic thing. I cut binding and purfling channels using a bearing piloted rabbet bit. I use a home made fixture to hold the router.

The binding channel must be cut parallel to the sides but the top is domed. Simply placing the router on the top to cut the channel would result in a binding channel that was wider at the bottom than at the top to you need some method of holding the router parallel to the sides. The fixture I use is a copy of a common design that's been floating around. I think it cost about $10 for the drawer slides and probably around $10 for the plywood I used.


Here is a shot of the router indexing along the side of instrument. I've found that single good passes make for the most uniform channels, but not necessarily the cleanest. I had a lot of fuzz to clean out by hand.



A shot of the purfling and binding channels.



And at long last, a shot with the bindings and purfling in place. Because this instrument is a prototype, I didn't do anything fancy. The binding is white ABS plastic left over from my guitar kit and the purfling is a simple BWB (Luthier code for Black White Black). I tape them into position using Stew Mac's Binding Tape . Once in position, I flood with CA glue . It should be noted that some types of CA glue can stain the spruce used for the top when absorbed by the end grain. To avoid this, I seal the binding channels with a coat of shellac. My current bottle of CA does indeed stain and the shellac has prevented staining.


Scraping the sides - Purflings are installed a little bit higher than the top and then scraped flush. Bindings are usually installed perfectly flush or a tad inset from the sides which are then scraped to be flush with the binding. We scrape the sides instead of the binding because we want a uniform thickness for the binding.

In scraping the sides I noticed what might be a big shortcoming of the compwood I'm using for these builds: there was serious cupping in the sides, perhaps 1/16". The only way to get rid of that on this build is to sort of taper the sides so that they get thinner toward the back of the instrument. I worked on it with card scrapers for about an hour and then needed a break. I checked the other frames and luckily, the frame for the "real instrument" is crowned which should be easier to deal with.

Today should be another productive day and I hope to post pics soon.

Top Bracing, Rim, Back Bracing

In spite of a lack of posting, I have indeed been working. I've done much and work is keeping me very busy so I apologize in advance for my brevity. As (mostly) usual, clicking on the pics will enlarge the images.

Below you'll find a picture of the braced top with the braces mostly completely un-carved. The top already has a rosette installed which I'll take some pictures of later - it's a very basic design and I've gone over this before. The sticks coming from above are called "go bars" and make it very easy to clamp things down. One problem though is that I have to make the base of the "go bar deck" stronger as it was deflecting under the load of the go bars.

The bracing pattern is the same as my last Харків (Kharkiv) version. The only difference is that this time I didn't I-beam the braces. Even so, the top came in right at around 450 grams - perhaps I beam bracing isn't that necessary. Below is a shot of the braces in their final shape.

Next is a shot of the completed rim:

I'm finding this type of rim a bit more difficult to make because of the exact shapes required. Because the final model (remember that this is just a prototype) will be using a pre made "Шемсток" or Shemstok, the angles between the neck and the rim have to be perfect. As it is in this model, they're not but I've got some ideas on how to get it right next time. Mostly it involves building assembly fixtures to guarantee that things line up the way they're supposed to . Good thing I'm building this prototype!

What I'll do for this version is to cheat the angle a bit on the shemstok to get it right rather than "straighten" the frame because it's much easier. That's o.k. for this one but the next instrument will require it to be perfect out of the gates.

Below is a shot showing how I've got to fix up some wavy-ness in the rim. If you read in a prior post, I'm using a material called "compwood". One of the side effects are that heavy clamping can compress the wood. Here's a shot of me flattening the area where the shemstok will be glued on:

Finally, here's a shot of the back with it's rough bracing glued on. I'm bracing this top a little more as I had some warpage issues at Kobzarska Sich last year. I'll be trying to shave the braces down until the tap tone of the back is either about a semitone higher or lower than the top (haven't decided yet).

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.