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I built this a year ago and am just getting around to using it. Tested on scrap and worked fine - what we want is a good 30 minutes of vacuum for brace gluing, right? This will go for much longer if my tests are any indication.

I will post more results tomorrow or Monday. I plan on gluing on the remaining x brace (only one is glued, the other not), bass bars and maybe finger braces at one time. Apply glue, put brace in place and tape down, stick it in the press and once again, yes, Bob will be your uncle. Hopefully.

I got the idea from Joe the Woodworker's site, I think. You have to buy a little valve (couple of buck, 10 minutes labor) that reverses the pump so that when you pull up, air comes out of the fixture, when you press down that air is exhausted.

DaveB

deadedith wrote:I built this a year ago and am just getting around to using it. Tested on scrap and worked fine - what we want is a good 30 minutes of vacuum for brace gluing, right? This will go for much longer if my tests are any indication.

I will post more results tomorrow or Monday. I plan on gluing on the remaining x brace (only one is glued, the other not), bass bars and maybe finger braces at one time. Apply glue, put brace in place and tape down, stick it in the press and once again, yes, Bob will be your uncle. Hopefully.

I got the idea from Joe the Woodworker's site, I think. You have to buy a little valve (couple of buck, 10 minutes labor) that reverses the pump so that when you pull up, air comes out of the fixture, when you press down that air is exhausted.

DaveB

I bought my vacuum press from Joe the Woodworker. It works great. I glue all my braces at the same time (top and bottom at separate times of course). I use a vacuum bag with valve attached on bottom.

When you vacuum the braces, are the top or bottom laying flat or on a radius board ot the specified radius or is that necessary?

To avoid stress and mis-alignment you should match the brace of the braces you have on hand and the clamping caul -- the easiest and the only sure way to do that is to use this simple caul:
http://www.kennethmichaelguitars.com/contourtool.html

I used those cauls of Ken's in the above photo, trimmed down to fit in the press. They work as advertised!
DaveB

kickngas wrote:When you vacuum the braces, are the top or bottom laying flat or on a radius board ot the specified radius or is that necessary?

I use a radius dish, same size as braces are radiused to.

Tim B

deadedith wrote:I used those cauls of Ken's in the above photo, trimmed down to fit in the press. They work as advertised!
DaveB

Some things just don't click with me. I tried go bars and sticks all over the place, solution - vacuum press. Then I tried Ken's cards and couldn't seem to get it right, solution - radius dish. Cost me extra but at least I can get it right now.

Tim B

PS I do use Ken's jig for cutting my binding channels, works like a charm.

I use go bars and disks . I also have a vacuum clamping system but I need to make a fold over instead of the bag. Again , the best advice is to dry fit things and be sure the joinery is true . A STRESSED JOINT IS DOOMED TO FAILURE !!!

I tried one of those vacuum sweater bags.....fit the whole radius disk in it with top and all. Stayed vacuumed for over 24 hours. Then, I did it again with braces....already somewhat scalloped. Like an idiot, I didn't think to soften the peaks...they tore through, as did the corners of the sanding dish the second time,and I lost the vacuum after a few minutes. Just wasn't thinking, but if you have round edges everywhere that stress will occur, it works very well.

You can see the peaks at the ends of the back braces in the pic below:

I would have gotten around to doing that! :-)

Thanks for the heads-up.
DaveB