truing up the soundboard edge before gluing

Steve-atl

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What method do you use to create the perfect seam in your backs and tops?

I have done it with sandpaper on a straight board and with a Jack Plane. Both methods seem to be hit and miss. Sometimes it goes well and sometimes it doesn’t. Right now I am going through the latter. It's very frustrating! I can't figure out what I am doing differently from the times it goes well.

Does anybody use a jointer? Even one of those benchtop jointers would be long enough for a ukulele top and back.
 
What method do you use to create the perfect seam in your backs and tops?

I have done it with sandpaper on a straight board and with a Jack Plane. Both methods seem to be hit and miss. Sometimes it goes well and sometimes it doesn’t. Right now I am going through the latter. It's very frustrating! I can't figure out what I am doing differently from the times it goes well.

Does anybody use a jointer? Even one of those benchtop jointers would be long enough for a ukulele top and back.

I use a simple shooting board and a small block plane, you don't need a two foot long plane to joint two 12 inch bits of wood, just ensure that the plane blade is sharp.
 
I use either a #7 or a sander, usually both depending on how the wood is behaving.
 
I use a simple shooting board and a small block plane, you don't need a two foot long plane to joint two 12 inch bits of wood, just ensure that the plane blade is sharp.

That's the thing I don't understand. The blades relatively sharp. I'm getting a nice ribbon of wood the full length of the board's. I'm really concentrating on keeping the same pressure as I used to plane but I'm putting a bulge in the center.
Do you guys plane your boards sandwich together at the same time?
 
If you get a bulge in the middle just use a plane to take down the hump, then go for the full length.

Honestly, a block plane is the only kind I own. I use it to rough in the seam and then use a 24" level with 80 grit self-stick abrasive to perfect the joint. I've joined thousands of tops/backs that way with never a problem. There is an aspect of purity to woodwork that I tried and discarded a long time ago. Such as a planed edge makes a stronger joint than a sanded edge. Sanded edges have never given me a problem.

It took a long time to get the hang of it, but these days I head straight for my 6x48 belt sander with an 80 grit belt. 30 seconds later I'm ready to glue. I can't even remember what happened to my long planes. They turned out to be pretty useless.
 
Planing to get a good joint takes practice! I used to be really bad at it, now I'm better (but still struggle sometimes).

There are two things which help:

1. Taking the thinnest possible shavings once you are close.

2. Transferring the point of pressure on the plane steadily, from pressure at the front when you start to pressure at the back as you finish. Otherwise you inevitably plane a hump into the plates. This is matter of feel, which only comes with practice. But once you get the feel, it's easy.

I only make a few instruments a year, so I lose the feel in between projects. What I should do (and you might try this) is to practice jointing two scrap pieces - make a good joint, then ruin it, then make it good again, then ruin it ... Once the feel is back, joint your real plates.
 
If you get a bulge in the middle just use a plane to take down the hump, then go for the full length.

Right. What I would do is start near the peak of the hump and take a shaving or two a couple inches long or so. Then back up an inch or two and take a couple longer shavings through the hump. Then back up again and take longer shavings through the hump, etc. Checking with a straight edge a few times during the process, of course, to make sure that it's going right.
 
Here's a method I've been using for many years with good success. It simply involves clamping your to plates into a jig and running a spiral carbide bit (mounted in a table router) along a straight edge. Not just any straight edge but a good one as your joint will only be as good as your straight edge is straight. (I think this one was from Lee Valley-$80). The spiral bit (from Eagle) is important since the cutting edge never leaves the wood (as opposed to a fluted bit which will leave chatter marks). The clamping surfaces are lined with 80 grit sandpaper to keep the plates from moving. One slow pass is all you need for a perfect joint. Once in a great while I'll run across a radically figured piece of koa that will give me a little trouble and I'll have to hit it with a sanding plane.
BTW, if you do sand your joints, don't go back and forth. Sand in one direction only or you'll be rocking the plates, leaving the inevitable bulge in the middle.
 

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Here's a method I've been using for many years with good success. It simply involves clamping your to plates into a jig and running a spiral carbide bit (mounted in a table router) along a straight edge. Not just any straight edge but a good one as your joint will only be as good as your straight edge is straight. (I think this one was from Lee Valley-$80). The spiral bit (from Eagle) is important since the cutting edge never leaves the wood (as opposed to a fluted bit which will leave chatter marks). The clamping surfaces are lined with 80 grit sandpaper to keep the plates from moving. One slow pass is all you need for a perfect joint. Once in a great while I'll run across a radically figured piece of koa that will give me a little trouble and I'll have to hit it with a sanding plane.
BTW, if you do sand your joints, don't go back and forth. Sand in one direction only or you'll be rocking the plates, leaving the inevitable bulge in the middle.

Nice looking GSD

I need to find something that works every time. I had glued up a plate a few days ago. I wanted to see how strong the joint was so I stressed it. It popped right along the glue joint. Not good.



Thanks
 
I'm really concentrating on keeping the same pressure as I used to plane but I'm putting a bulge in the center.

One of the things you have to get used to is buying or making some pretty specialized tools. This plane works well on those pesky humps but you need 25 ton hydraulic press to bend it.

47414320851_aa4b05ac7f_z.jpg




But seriously, I use a flat plane and shooting board and always finish with some sticky-back sandpaper on a flat surface. Before I got a granite plate, a cast-off piece of 1/2" glass did the same job.

40448998743_c6dacceeef_z.jpg


47361755612_48906ca4c2_z.jpg
 
One of the things you have to get used to is buying or making some pretty specialized tools. This plane works well on those pesky humps but you need 25 ton hydraulic press to bend it.

47414320851_aa4b05ac7f_z.jpg




But seriously, I use a flat plane and shooting board and always finish with some sticky-back sandpaper on a flat surface. Before I got a granite plate, a cast-off piece of 1/2" glass did the same job.

40448998743_c6dacceeef_z.jpg


47361755612_48906ca4c2_z.jpg

Where did you get that massive right angle piece of metal?
 
Here's a method I've been using for many years with good success. It simply involves clamping your to plates into a jig and running a spiral carbide bit (mounted in a table router) along a straight edge. Not just any straight edge but a good one as your joint will only be as good as your straight edge is straight. (I think this one was from Lee Valley-$80).

Hey, I just called Lee Valley and sent them one of your photos of the straight edge. They do not carry it. Have any other ideas where you got it.

I did a little google search for straight edge router jig and did not come up with anything.

Thanks
 
Hey, I just called Lee Valley and sent them one of your photos of the straight edge. They do not carry it. Have any other ideas where you got it.

I did a little google search for straight edge router jig and did not come up with anything.

Thanks


They were confused by the photo. They got oodles of straight edges. As Resoman mentioned, the Starrett are the best. Just don't drop it! I steel wool and wax mine regularly. http://www.leevalley.com/en/Wood/Search.aspx?action=n
 
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