Archive for the ‘Kerfing’ Category

Back glued on

Monday, September 27th, 2010

I’m getting behind here! The back was glued on a couple weeks ago. To try to catch up quickly…

First, the builder’s label had to be glued in position.


Builder's label in place with ermine border I designed


Inside of back with label and center support strip

For nostalgia’s sake, I shot two last views of the inside showing the bracing and bottom of the soundboard, before the back was glued on.



And thanks to Leonard for the use of his clamps…


Back clamped in place, t-shirts protecting top and bottom

The big unwanted surprise during this process was how much the back slid around due to the glue before I could get two clamps tight enough to hold it in place. It was quite unsettling until I got that settled. Hopefully, enough glue got into the kerfing to make a good bond, and there wasn’t too much of it smeared on the label.

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.


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.


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.


Slightly curved sanding cradle

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


Two 3D views


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.


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.



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.

3D hurdy-gurdy

Monday, May 10th, 2010

With Hollywood doing 3D photography in their latest movies, I decided to get in on the act, including an occasional 3D hurdy-gurdy construction photo here. I have an old Pentax Optio 430RS digital camera. Absolutely nothing to brag about, but it does have an interesting 3D setting, something you don’t see every day on the latest fancy cameras.

 ”The new [in 2002] digital Optios record one picture on one half of the file and then you take a second picture by moving the camera slightly left or right to recreate the stereo lens effect. The camera displays the first on the left and the composition of the new one appears on the right. A grid is provided so that you can ensure perfect alignment.”


Optio viewfinder in 3D mode

I’ve always been interested in antique stereoviews and stereo photography, so when looking for a used camera several years ago, and seeing a 3D feature on this one, I had to go for it. If you look at the web page above, you will see that you don’t need a special camera to make your own stereoviews.

To view the images, you will either have to get a simple viewer, like the cheap one I got on ebay for $3-$4, or better yet — train yourself to cross your eyes until the two halves overlap and align. Focus on a spot in both views, and cross your eyes [like you are trying to look at your nose] keeping track of the two spots until they merge, which is when you should notice the 3D depth effect kick in. You will see three images, the middle one being in 3D.

I have to warn you that it is possible to cross your eyes two ways and get the pictures to overlap. If you do it the other way, the depth will not work and the picture have the appearance of being turned inside out. I have made mine in the traditional way old stereoviewers worked, with the right eye’s view on the right, and the left eye’s on the left.


Simple plastic 3D viewer that works well on computer images

Hurdy-gurdies being rather complicated gadgets, I thought they might look more realistic in 3D. When crossing your eyes, focus on a prominent detail such as the black dot of the bearing. Since these blog images are so small to begin with, it is fairly easy to do without a viewer.


Just when you thought you were done looking at clamped kerfing

You can see where I had been trying to cut the outer edges of the side stripe grooves with my X-acto knife in the photo.

Kerfing 3

Monday, May 10th, 2010

The middle kerfing, top and bottom, was completed on Saturday.


Another picture of rows of green clamps, like parrots on a fence

Now to move on to other things!

Kerfing 2

Wednesday, May 5th, 2010

Last week I finished the kerfing on the head end. So now both ends are done. I’ve gone as far as I can go on the kerfing until I get the bearing brace put in.



By the way, using paint thinner to wipe the grease-like marks left from the plastic tips on the clamps seems to have taken care of them.

Last Thursday I sent the brace back to HGC for a new bearing to be installed.

Kerfing 1

Monday, April 26th, 2010

Yesterday I glued in the first kerfing on the bottom alongside the tailblock, below the tail reinforcement strips:


Tonight I did the kerfing on either side of the bottom of the headblock:


I also glued in the interior supports for the strap buttons:


I put strips of coated paper between the wood and the clamps tonight. The green plastic on the clamps is leaving darkened spots on the wood where they were, sort of like a grease stain. You can see the spots in several of the pictures where other things have been previously glued in. I sure hope those on the outside don’t show when I’m done!

Tail reinforcement strips

Saturday, April 24th, 2010

I glued in the 1/8″ thick spruce reinforcement strips on either side of the tail block today.


Green map pin forces bridge brace and body its direction to center on plan

I figured it was okay to glue them in out of sequence according to the directions, before the bearing brace, which isn’t in yet due to the bearing fitting too tightly in the threaded hole. It can be seen on the sidelines in the photo above.


Curved bottom edge of spruce support strips