Archive for June, 2010

Top edge rounded

Thursday, June 10th, 2010

Last weekend I got the top edge rounded.  To roughly get the bulk of the excess removed, I used a small block plane that a friend, Leonard, loaned me. Then I used the sanding cradle I had made to get the final curve.

CurvedTopEdge-Pre

View of the amount of edge above braces needing to be removed

I was worried about the planing, but it went well. The slots in the kerfing caused it to buck some, and I had to be careful which way I went, due to the grain of the kerfing, which would chip out too much if I went the wrong way.

Plane

Planing down to just above the braces on outer edges

The sanding was slow, but yielded nice results. The part that took the most fiddling was making sure that the amount removed on each side was the same. The sides were reduced 1/8″ at their widest point.

SandingCradle3D

Slightly curved sanding cradle

Pictures of the results, showing the sides flush with the braces:

CurvedTopEdge1

Two 3D views

CurvedTopEdge2

This may give a better feel for the subtle curvature

Time to get serious about what I’m going to do about the soundholes, since the soundboard is next.

Better safe than sorry

Friday, June 4th, 2010

Another thing that’s been keeping me busy is reinforcing the inside with strips of thin birch plywood. I was worried that I’d significantly weakened the body where the stripes were put in, expecially because my initial plan was cutting the edges of the channel with an X-acto knife, with which it is easy to slice too deeply. I had already done a bunch of cutting that way before getting to borrow Jerry’s nice tools which you could set the depth.

I figured over time and with temperature and humidity changes, it could possibly crack along the weakened grain. I didn’t trust the glued-in stripes to keep it strong. They only go to the edge of the problematic cuts and don’t straddle them, so they can’t strengthen anything.

StripeReinforcement1

I was going to use some of my veneer, but I found some great Revell plywood at the hobby store. I got two sheets, which are 1/32″ x 6″ x 12,” and that did the job. Much stronger than veneer would have been.

StripeReinforcement2

  

StatueLibertyYeah, it doesn’t look so great, compared to all the nice mahogany, but neither does the Statue of Liberty on the inside, and look how long she’s held up with all her unsightly reinforcements. These’ll be permanently covered and inaccessible, unlike the Statue of Liberty. Anyway, I won’t tell, if you don’t.

I also decided to go ahead and put some leftover kerfing on the tail end over the reinforcement strips, in case I wanted to add sympathy strings later. I did both sides for balance, and it gives more gluing surface for the top and bottom.

The body is finally ready for the arching of the top. That should be exciting! I have put Post-it tape on top of the braces and scribbled on pencil so I can detect when the sanding gets down to that depth, which is the goal, of course.

Headblock change

Friday, June 4th, 2010

This took another couple hours to carefully cut a new recess for the wider and thicker piece of cocobolo, plus getting everything to fit right, which I wasn’t really looking forward to. But it went fairly well.

HeadblockCocobolo1

New wider and deeper channel with the three pieces to go in it

The three pieces fit nice and snug and looked great on the test, so it was time to glue. Tin foil was put on top to keep any squeezed-out glue from bonding with the oak clamping board. The popsicle sticks are also seeing more action.

HeadblockCocobolo2

It's in there, now — with plenty of glue

 And, after being clamped all night, and all day while I was at work, and following a little cleanup this evening…

HeadblockCocobolo3

Now, that's more like it!

I was surprised the wood didn’t lighten when filed and sanded, like the other cut-side. But it looks great like this. Hopefully it will show enough with the peg head on that it have been worth the trouble!

Headblock, plan B

Tuesday, June 1st, 2010

I decided I needed something thicker than veneer, and I have a bunch of different 1/4″ thick hardwoods. I’ve been narrowing that selection down, and planning how I was going to do it with limited tools.

Since the knob is cocobolo, I chose to have that wood represented on both ends of the instrument.

I cranked up my table-mounted router for the first time in years to smooth the rough outer edge of the 12″ board. Then I cut a 1 1/2″ width off on my scroll saw, using my versatile metal ruler as a fence. It made a pretty smooth, straight cut. [You do what you have to, without a table saw and other proper tools.]

CocoboloPlank

Cutting off cocobolo strip on scroll saw, using metal ruler as a fence

I didn’t want to cut a recess to inlay the whole 1/4″-thick piece, so I tried splitting it with my router with a bit that cuts a 1/16″-wide notch. It would only cut 5/8″ into the wood, so running it along both edges left a 5/16″ section in the middle that I had to cut through with a hand miter saw. A tricky couple of steps that had a satisfactory result.

CocoboloRouter

Cutting narrow notches in the sides to split the thickness

It was surprising how much lighter and more colorful the wood was on the inside. The piece is now over 1/16″ thick. No worries about sanding through, this time. I suppose sanding the dark outside will make it lighter, too, only to darken again over time.

CocoboloKnob

Outside and inside of sliced cocobolo piece, with cocobolo knob

I didn’t want to do anything to alter the hurdy-gurdy until I saw how these various “will it work?” steps came out. So far, so good.