shooting board

[Tim R]

Hello all.

I need to mate and join my 00 guitar top and I’ve been looking at the shooting board described here:
http://www.kennethmichaelguitars.com/Jo ... alves.html

He says simply to use a piece of 1x2” material glued to the edge of an mdf board with sandpaper on one side. There is no mention of the need for the sandpaper side to be flat? Clearly it must be, though, so any ol’ piece of wood wouldn’t do, right? How does one get one side of a strip of wood sufficiently flat so that the top will mate well enough to pass the light test?

Thanks,
Tim

[SKBarbour]

I'm sure some more experienced folks probably have some better suggestions, but I used a plane to get it close then touched it up with a 2' level with a strip of 120 grit attached to the side. I only used the level because my planing technique wasn't quite getting it.

[tippie53]

I don't like MDF as it is not very stable. You can use a level and use PSA sandpaper. There are many ways to make a good joint. A shooting board uses a hand plane. If you want to use sandpaper for making a joint , you can use a steel level . or a table saw top.
My preference is a granite surface plate as this is flat to .00005 . You can get granite pieces at counter top places , that would be more stable and accurate than MDF. I learned a long time ago MDF moves too much . Pattern grade plywood is more relyable to make that jig and then you are still only as accurate as the tool that made it.
Do you have a router?

[deadedith]

I've joined a few tops with the KMG method, it works just fine. If I was joining more often perhaps I would tool up a bit more for that procedure. I did use a straight edge on the mdf before using it, though - like John says, it's not completely stable - but my piece stayed straight for over a year.

[Tim R]

John,

Do you have the wood oriented vertically while you slide it on the horizontal granite surface? If so, then I assume you use some kind of vertical stop to keep the wood at a constant angle to the granite it it slides

I tried doing this against plate glass just as a trial run and was just holding the wood vertical with my hands. Despite my best efforts it rocked by and forth from vertical a bit as I slid it. When I did the light test, it was pretty tight on one side but with a small consistent gap on the other. I think the rocking rounded the wood slightly on the outsides but did not affect the mating at the center, yielding the results I just described, if that makes sense.

Tim

[Ben-Had]

John,

Do you have the wood oriented vertically while you slide it on the horizontal granite surface? If so, then I assume you use some kind of vertical stop to keep the wood at a constant angle to the granite it it slides

I tried doing this against plate glass just as a trial run and was just holding the wood vertical with my hands. Despite my best efforts it rocked by and forth from vertical a bit as I slid it. When I did the light test, it was pretty tight on one side but with a small consistent gap on the other. I think the rocking rounded the wood slightly on the outsides but did not affect the mating at the center, yielding the results I just described, if that makes sense.

Tim

That makes sense and is one of the problems with that method. The rocking is the problem and different people can have their gaps in different spots based on how they apply pressure. The "Easy Jointer" (you can google that tool if you're not familiar with it) uses that process and some have to place tape on the glass in certain spots to compensate for the rocking. On my last I used some hold down clamps on a straight edge board and a flush trim router bit to cut both halves at the same time. Came out perfect so I'm going to try that again.

[deadedith]

With the mdf shooting board, the pieces to be jointed are lying on their side, so gravity works for you, not against you, and it is easy to keep steady pressure against the sandpaper.
There is a school of thought that sandpaper does not give a good mating surface, but otoh many builders for many years have used the method and I have not heard of any failures.

[Tim R]

Okay guys. Based on the trial run described above, my plate glass on top of my work board appears to make a pretty flat surface (the “inside surface” of the top passes the light test). So, I’m going to try sanding the edge of a piece of 3/4'’ mdf or pattern grade plywood on that surface, careful not to rock it, and use that on a horizontal-type board. Once that strip is glued to the board, I may also glue a thin sheet of ply to the board, butted against the flat strip, so that any possible slight rounded edge on that strip is not involved in the sanding. I’ll let you know how it goes.

By the way, laying the top wood on the plate glass with fluorescent light under it works very well for the light test. My quality control at that stage at least should be good.

Tim

[tippie53]

using MDF as the square agent for the glass should get you there. A table saw top also works very well if you have one

[tippie53]

http://www.youtube.com/watch?v=npd0wnpjKa8