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.