Search This Blog

Tuesday, May 21, 2013

Back to the lute

I'm back to working on the lute now. I have fitted the counter-cap to the inside of the bowl (it has a much better shape now), and I've glued on the bridge (with hide glue, of course). I now have to do a bit of tap tuning by shaving away some of the braces on the underside of the belly (although this will, as usual be more luck than judgement!).

I also have to glue some paper reinforcing strips along the rib seams on the inside of the bowl.

Sunday, May 19, 2013

Arching (part two)

 Here are the results from my first practice run with the overhead pin router. I started with a piece of walnut, fixed with double-sided tape to the holding table. I started the routing with the uppermost contour and proceeded to go deeper each round.

It was pretty straightforward, and reasonably quick. There were a couple of issues to fix, though. First, I need to find a better way to remove the chippings as they tended to find their way under the holding board, giving its movement a 'gritty' feel. Perhaps the answer will be to cut some slots in the table itself and figure out a way of connecting these to my dust extractor.

The second issue was setting the depth of the router cutter, which was a bit fiddly. I think that a threaded rod fitted to the router (one turn per mm) might work, or if I'm feeling extravagant, a digital depth gauge.

...part way through...
I will finish off the back sometime soon and who knows, perhaps a walnut F5 mandolin will form around it!

...all the contours cut

Saturday, May 18, 2013

Arching (part one)

I was thinking about making archtop backs and bellies a while back and I came across an arching pattern from Andrew Mowry's website. This set me to pondering on the best way to do the initial carving on one of these and I decided it called for an overhead pin router. Having previously made the front for a Les Paul guitar, I know how much work is involved and how difficult I found it.

I sketched out my design in Google Sketchup and put it together from bits I had round the workshop (except for the rubber castors which I bought online).

Pin height adjuster
The router height above the table is set using its 'plunge' and the pin height is set with a modified lever-operated clamp mounted underneath the table. The routing table can be adjusted up or down by 10cm if needed as it's fastened with bolts and wing nuts running in vertical slots. .

The real thing...was not quite so neat!
The router is mounted one third of the way across the width of the table to allow wider pieces to be worked on. I also added a safety STOP switch and a box for the spare pins etc.

Underside of the holding board
The wood to be carved (in this case a back) will be stuck into place onto the top of the holding board with double-sided tape and the template (in fact a mirror image) is mounted on the underside with fixing bolts. The template set corresponds to each of the contours on Andrew Mowry's plan. In order to engage with the pin properly each plywood contour was 5mm deep. I found that four of these could be stacked and glued together for convenience.

The idea will be to start with the pin fully retracted and take the thickness down to 17mm. Then the pin is raised by 5mm, and the router cutter is lowered to 16mm and the first contour is cut. Then the cutter goes down to 15mm and the pin up another 5mm and cut again...and so on.

Now to see if the theory works out in practice!

Arching Template sets

Sunday, May 05, 2013

The Tenor Uke is finished!

The tenor uke had its strings fitted today - a set of nylgut ones from Aquila. They seem to take ages to stop stretching and to stay in tune, but I have read to expect this. It's certainly different from the usual mandolin wire.

As usual, there have been a few 'compromises' along  the way. The strings didn't quite align properly at the bridge (I think the hole was a millimeter or so out)  but I was able to adjust this by making grooves in the saddle. The kerfed lining, visible through the soundhole looks a little slapdash as I cut it by eye - next time I will have to make a jig to to this. Also I still haven't reached a satisfactory standard with the finish - I'm wondering about investing in a set of buffing wheels for my drill press.

The binding has worked really nicely, although quite a few bits snapped when bending them to the tight curves on the ukulele. With the binding around the heel I actually had to laminate in situ, as there was no way to bend binding to such a small radius.

The instrument is fairly loud and bright (which was the tone I was hoping for) and as the actions has been left quite high (3mm at the 12th fret) it's can be played 'robustly'. Here is a quick soundfile.

Overall, I think I have done a good job, and once again I have learnt a lot. I will buy a quirky gig bag for it and hope that it goes down well at birthday time.