Cutting Lap Joints in the X-Brace

[tippie53]

restored

[Darryl Young]

Read a response on the OLF where some folks use two Freud Diablo 7 1/2" circular saw blades with dado "cleaners" in between to get the proper thickness. Well, I have a dado blade set I've rarely used so why not try this? The thought of one pass through the blade appealed to me and I figured this method elimiated most of the risk of cutting the channel too thin so I gave it a try.

Put the two outside cutters on the table saw (each cuts 1/8" thick) and made a pass through scrap and did a test fit with one X brace arm. It was a bit too tight. The dado set had washers that were 0.009" thick so I put one of these between the blades, ran another test cut, and had a perfect fit. Yeah!

So I measured the depth of cut and adjusted till is had it a few thousands less then half the brace height on test cuts (measured with dial calipers).

Now I had to get the angle correct. I went to 95deg (same as the angle on the plan I've drawn) and made a test cut and adjusted till the angle came out correct (touchy!).

Made my cut on the real X-Brace arms and it's pretty good! I will sand the depth of each channel slightly but it's almost perfect now. Here is a pic:

X-Brace.JPG

[tippie53]

It may take a few days but I have to make some bracing and can show the table saw method and the razor saw. On the table saw you have to watch for tear out. If I am doing a single set of braces a razor saw chisel and file , takes only a few minutes.
I don't use a vise but I do use a back stop like a mitre fence

[tippie53]

http://www.luthiersforum.com/forum/view ... 17&t=15971
This is a link to OLF and a tutorial by Lance Kragenbrink. It may have some interest for many

[Darryl Young]

FYI, I messed the radius up on this X-Brace.......curved up too much right at the rim. I sure didn't want additional radius/stiffness there so I remade my X-Brace tonight.

Started by taking a split red spruce wedge and splitting it more till I had 2 pieces a little over the width I needed. Can't wait till I see John's video on this as it seems I waste more spruce than I should. I used the flatest split face down on my drum sander and sanded till the other face cleaned up......then flipped and sanded till the opposite face cleaned up. Flipped once more and sanded to thickness.

One thing that helped me this time was leaving the brace taller than needed so this time I drew the entire radius on the bottom where before I held the template closer to the edge and my pencil went off the edge for 4 or inches. While it was still square, I cut to the correct height on my tablesaw (measuring from radius line). Then I planed the radius to the line.

This time I put 120g in the dish instead of 80g and I placed the braces side by side so there was less tendency to wobble sided to side. I used very light pressure and I tried to put the pressure toward the rear of the brace away from the direction I was sanding. All I was trying to do was clean up tiny spots left after planing and it worked perfect.

Finally, I set the height on my dado blade and cut the lap joint (got lucky with the perfect height). I had left the braces slightly thick (around 0.265") so then I took very light passes on the braces in the drum sander till I had a thickness that fit the lap joint.

I feel better now.......hate doing things twice........but I learned what to pay attention to! Everyone's suggestions here and on the OLF were very helpful, thanks!

[Kevin Sjostrand]

I never thought of making these cuts on the table saw. A small hand saw and chisel work pretty well and fast but you have to have the angles marked correctly. It sure is easy to get wrong. How do I know??????

Kevin