Archive for the ‘Bracing’ Category

Keychest mounting holes

Saturday, March 12th, 2011

KeychestFront16Before gluing on the decorative side of the keychest, closing it in and making it awkward to work inside, I wanted to drill holes for the two mounting screws [or dowels] in the base of the keychest front.

[Yes, the base is a mess due to having to reduce the height of the keychest after originally making a stronger overlapping joint for the foot.]

KeychestFront17

The other advantage to doing this before enclosing the keychest was I could get the angle I wanted if I could see the base. The bearing brace near the wheel opening, that the keychest screws attach to,  is slightly in front of the front of the keychest, requiring angled holes.

KeychestFront18

The holes are not their final diameter, but at least I now have them in at the right angle and can enlarge them later from the bottom with an electric drill.

Hopefully these holes are aligned right and the base is strong enough.

Keychest brace

Sunday, March 6th, 2011

I had a scrap of mahogany left over from making the front end of the keychest. It was the same width, so I decided it would make a good brace for the middle of the keychest, under the keys. This will give the whole assembly extra strength, having extra gluing surface for the sides, as well as help keep the sides from warping, or whatever. This is something not called-for that I’m adding. Probably not necessary, but I doubt it hurts anything, either.

keychest-brace

Central brace glued into position

Keychest front reinforcement

Sunday, January 2nd, 2011

At the end of October, I retrimmed the keychest after putting in the wheel and  realizing some of the measurements were off. At that time I said:

Unfortunately, this necessary shortening messed up the nice double rabbet joint I had on the bottom of the keychest front. Now the base is thinner and weaker than the original piece. I will probably end up adding a second strip on top of the base to reinforce the joint.

So, over the holiday I made this reinforcement strip for the base out of some scrap mahogany.

KeychestFront13

Keychest front reinforcement part for the base

Not as strong as it was originally, but better than after the re-trimming of the bottoms of the keychest parts. The keychest will have screws [or dowels] going through the base of the front into the internal bearing brace of the instrument. I believe the screws will have to be angled forward to reach the brace, so that may help with this situation?

KeychestFront14

Part glued into place

Trimming the keychest

Thursday, October 28th, 2010

I put in the wheel for the first time since gluing on the back. I needed to check the fore-aft keychest measurement, because I thought I had the side pieces slightly too long, so that they extended past where the sides of the body attached to the head block.

The instructions say the center of the 7th key has to be exactly 6 15/16″ from the bridge. And the bridge has to be about 7/16″ from the wheel. So, checking all that with the pieces in place, I found that the sides were in fact too long by 1/8″ to 3/16″.

KeychestFitCheck1

Chopstick serving as 7th key to measure proper spacing from the bridge

In the process, though, I discovered something else a little more bothersome — I had the whole keychest way too high. When putting a straightedge on the angle of the wheel, it rested right on the keyshafts! [At least it appeared I had cut the bottom of the sides at the right angle.] The best I could tell, the sides and end pieces needed to be cut down on the bottom by about 7/32″ to have the chanter strings the right distance above the keys. That’s almost a quarter of an inch. How’d I get so far off?

  1. When cutting the bottom edges of the keychest side pieces, I had overcompensated for the curvature of the soundboard. There is hardly any curvature at all to deal with 1 1/2″ either side of the centerline, even though I had doubled the curve amount from that specified. I knew I had to sand the keychest bottom to fit the soundboard curvature, but  I had about 1/8″ extra there — too much to sand.
  2. The wheel seems to sit lower in the body than on the plans. This is not a problem with the plans, but is related to some adjusting I did when making the braces in the body. I had added some 1/8″ thick wood to the tops of the large braces before rounding them. The reason I gave April 15th for this was…

You can see an 1/8″ thick strip of wood has been glued on top of the brace. The short brace is 4″ high, but the two larger braces were 1/8″ shorter. This modification to the larger ones makes all three 4″ high, which is the height of the body. This also makes the threaded hole for the bearing closer to the same height of the shaft hole in the end of the body. I could have sanded down more from the sides of the body and the top of the short brace, but decided to try this.

In hindsight, perhaps I should have made the small brace shorter and sanded down the entire top of the body more. Anyway, this obviously effects the wheel height, lowering it by whatever was left after rounding of that 1/8″ strip. You can see the strips I’m talking about here.

So, this accounts for why I was almost 1/4″ off on the first cutting of these pieces, despite all my attempts to accurately measure the plans. Jerry was good about letting me come over and re-do all these tedious cuts last night. Everything went well, thanks to his careful expertise and excellent tools.

Unfortunately, this necessary shortening messed up the nice double rabbet joint I had on the bottom of the keychest front. Now the base is thinner and weaker than the original piece. I will probably end up adding a second strip on top of the base to reinforce the joint.

KeychestFront12

The front piece after re-trimming, beside original piece

This front piece is now the same height as the original — what a coincidence! I was wondering why it was so much higher before. Hopefully, that’s a positive sign I’m more on the right track, now.

The good news is, if you’re making one of these kits and sticking to the playbook, you won’t have any of these self-inflicted problems. The keychest will be all put together, cut the right size, and everything!

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.

BackLabel

Builder's label in place with ermine border I designed

BackInside

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.

Inside-LastView1

Inside-LastView2

And thanks to Leonard for the use of his clamps…

BackGlued

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.

Back about ready

Monday, July 12th, 2010

Over the weekend I used a cabinet scraper and sanding block to level the decorative center inlay strip on the back. I had to do this before adding a bulge to the inside, which would make working on the outside more problematic, not being able to lie flat any longer.

The bulge is a center reinforcement strip that the manual refers to that goes over the back seam in the large gap between the braces. No part was included for this and so I suppose it is an outdated step. But I decided to make one anyway. I used a 1″ wide by 1/8″ thick piece of wood I had on hand. The distance between the braces is 8″. I made the strip 7 1/2″ long. After rounding the edges and doing some careful measuring to make sure it would be in the right spot in relation to the braces when it all was put together, I glued it down.

The other two things I did was trace the outline of the body on the back piece, and then trim it closer to this line on my scroll saw.

CenterSupportStrip

Center support strip will span the gap between braces inside the back

Now the back is ready to glue onto the body, except for the inside label. I haven’t made up my mind what I’m doing about that, if anything. One came with the kit, but I might do something else. I went to a label/sign shop today to see about an engraved name tag sort of thing. No rush deciding on that, since I have to first do all the decorative edging around the soundboard first.

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.

Sanding cradle design

Thursday, May 13th, 2010

SandingCradle1I don’t know what to call this thing, so I came up with this name. It is the route I’m taking to round the top and bottom edges of the body to match the bowed braces, to give a curve to the soundboard and bottom. I expect it will give me a more uniform, smooth and symmetrical curve than sanding by hand.

I located some 3/4″ plywood in the garage, as well as a piece of 1/8″ masonite which was once the backing for a full-length mirror. The plywood will be the base and the masonite will form the curved cradle. The masonite unfortunately wasn’t the width of the instrument, so I had to cut it into 14″ lengths and put two pieces end-to-end. The two pieces of the cradle will be held in place by small wire brads.

To create the curve, I glued two 24″-long, 1/8″-square basswood strips to the plywood base, their combined width being 12.5″, which is about the width of the hurdy-gurdy at its widest point. I hope this technique will give me a curve that fairly closely matches the bow of the top of the braces, which drops 1/8″ on the widest one.

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.”

OptioViewfinder

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.

3D-viewer

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.

3D-01

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.