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'.

Finishing, lessons from my first guitar

(Click on any picture for a larger version)

To help expand my knowledge of instrument building, I decided to build a guitar (as I've mentioned in a previous post here).   The guitar is almost finished and I'll now go into some details on my finishing schedule.  The type of finish is up to the maker and I wanted the "so glossy it looks like it's wet" look.  Many builders feel that whoever decided that guitars should have that high gloss finish should be dug up from his grave and shot....again.  This is because that glossy look is really time consuming to achieve.  Taylor guitars have done a great job of re-popularizing the matt finish in high end guitars.  They did that because it's way less labor intense to do a matt finish vs. a gloss finish.

Finishing starts with a good preparation of the surface.  I generally sand the bare wood to 320grit.  Next because the back and sides are made of a porous wood (East Indian Rosewood) we need to do a pore fill otherwise there will be tons of little pits in the finish under each pore.  I used Z-poxy finishing resin. The  Z-poxy is a bit messy but does a really good job of filling all the little pores.  It takes almost nothing, much less than one ounce to put a coat on the guitar.  It's applied by pouring a few drops on the guitar and spreading it in with a credit card. Here's a good tutorial on how to do it.  

I used two coats of Z-poxy, sanding back to bare wood after the fist coat and trying to leave a thin coat after the second session.  The Z-poxy really "pops" the grain of the EIR.  The one rub is that when sanding the second coat on the neck, there were a couple spots where I sanded back to bare wood. They are visible as faint light spots on the heel of the neck.  Normally one would re-coat the neck but it wasn't too bad and I wanted to finish the guitar so I could get back to bandura building!  After a light coat of shellac, it was time to spray on the final finish.

The finish I'm using now is the Stew Mac branded Target Oxford USL. They're both the same thing I just ordered from Stew Mac because I had a couple other things to order from them as well.  Nitrocellulose lacquer is the "gold standard" of guitar finishes but it's also quite toxic and quite explosive (nitrocellulose is also gun cotton) and I'm just not interested in spraying it in my basement.  It can be done but you need some pretty elaborate venting systems which I don't have.  Polyester finishes are becoming quite popular with builders now too because they are very durable and because they're catalyzed, you can spray one day and buff out the next.  These finishes also have a very steep learning curve and if you screw up, you might end up having the finish harden in the spray gun which doesn't interest me either.  The waterborne finish I'm using is relatively benign, it doesn't stink up the house, and is safe to spray at home so long as you use a respirator.

For my spray gun, I just recently picked up this gun to replace my old school high pressure gun.  The HVLP systems have much lower over spray which means less dust floating around the shop.

Finally, even thought Stew-mac recommends building coats using their sanding sealer, I chose to use all USL this time around so I wouldn't have to buy two products.  Now to the finishing schedule itself.

The settings I used on the gun were the following:

1.2mm tip, 27psi at the handle

Air Screw - 1.25 turns out

Fan Screw - 1.5 turns out

Fluid Screw - 2 turns out (tried 1.75 but didn't like it.

Applied 9 coats over two days and did a quick level sand

Applied 4 more coats and measured the film thickness by peeling off some masking tape. Thickeness was .005" (13 coats so far).

Applied 5 more coats and measured, .007" on tape and .009" in the soundhole cover.

The guitar now had to hang for a month to allow the finish to fully shrink and harden.   After all this work, the finish looks like the photo to the left.  A far cry from the glossy look we're after.  To get from there to glossy is where the work really starts.  Level sanding and buffing.

Level sanding is where you use sandpaper and sanding blocks to knock down the orange peel to make a perfectly smooth surface. I started with 400g which is a bit risky: it levels fast but there is a risk of sanding too much and the 400g scratches are really large.  I had a hell of a time getting the surface scratch free and think that next time I'll start with 600g.  It's also essential to use good sandpaper.  I prefer the 3M free cut gold because they can be used dry and don't load up.  I do brush off any sanded finish and the paper after about 10 to 15 strokes.  For a sanding block I use either a small rubber eraser or a black board eraser for curved surfaces.  I went from 400g to 600g to 800g dry, then switched to an Abralon 2000g pad on my random orbit sander (my thumbs were hurting pretty bad at this point from holding the little sanding blocks).  I then took it to the buffer (you can see it in the background on the picture on top).  The results were disappointing.

Apparently I didn't spend enough time with the higher grits after the 400 because there were still a lot of scratches that could be seen at certain angles.  I had to go back to 600g, 800g then the 2000g.  I had to go back and re-do areas of the guitar several times because of this problem. I also used some 1000g wet paper in some areas to get rid of 800g scratches. I think this could be avoided with the following schedule:

Start with 600g, it might take longer to level but there will almost certainly be no deep scratches.

800g dry

1000g abralon pad wet (I didn't have one this time but I found some on line)

2000g abralon pad

Buffer.

By the way I also have a 4000g abralon pad but found that you can go from 2000g to the buffer and not have any scratches.  (on the other hand, a buddy, Mark Swanson, says that on nitro he can go from either 400g or 600g, don't remember, straight to the buffer with no scratches!!! what the hell am I doing wrong?).

Once all the sanding was done, it was off to the buffer for about a two hours on the medium wheel followed by about a half our on the fine wheel.  I suspect had I done a better job level sanding I could have spent less time on the buffer.  

At the end of the day (about 7 hours total level sanding and buffing), I ended up with the finish in the shot to the left.  It came out pretty nice I think.  I suspect that as I get better at this I'll be able to get it done in less than half that time.

After finishing the neck the same way I attached the neck to the body.  All I have left is to glue on the Bridge, make the nut and saddle and final setup.   

Phew! What a long post.  Hopefully someone will find it useful.