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Brisge Clamping with Go Bars
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=7817		 Page 1 of 1
Author:  RussellR [ Tue Aug 01, 2006 7:02 pm ]
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Inside a thread on another Forum, someone said they use their go bar deck to clamp the bridge on, which I found interesting, thinking about it the only downside I see is the potential for a rod to slip and bang into the top, but I guess you could make a protective mask.

Anyone doing this ?

What do you guys think to this idea ?
Author:  JBreault [ Tue Aug 01, 2006 11:11 pm ]
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It seems to me like a lot of pressure being exerted down on the middle of the top without any support on the other side. I feel more comfortable with a caul on the inside and the clamp sandwiching everything together.
Author:  RussellR [ Tue Aug 01, 2006 11:21 pm ]
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Hi Joe

I thought this too, but then is vacuum not the same ?

Guess with Vacuum, matbe the clamping pressure is more even.
Author:  JBreault [ Tue Aug 01, 2006 11:38 pm ]
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With a vacuum, isn't the top being "sucked" into the bridge? There's no excessive downward pressure, just the air between the top and bridge being removed.JBreault38931.3603587963
Author:  crazymanmichael [ Tue Aug 01, 2006 11:40 pm ]
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with go bars the pressure is on top, pushing it into the box. this is the reason internal jacks have to be used under the bridge to counteract the downward force of the bars.

a vacuum bridge clamp only affects the area around the bridge and the atmospheric pressure is only on that section of the top and and is balanced by the pressure inside the box.

if you were to use a vacuum bag as for veneer pressing it would crush the box.
Author:  Todd Rose [ Wed Aug 02, 2006 1:45 am ]
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In the class I took with Sergei de Jonge, we used go bars to glue the bridges on. His go bars are really thick, too. We did not use any jacks on the inside of the box. We did set the back into a radiused dish for the operation. It worked. No damaged boxes. As far as I know, he does it this way all the time.

I now use a vacuum clamp. Even though I've seen and done the go bar method, it makes me nervous.
Author:  MSpencer [ Wed Aug 02, 2006 1:59 am ]
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I am with you Todd, probably would work fine, but a slip could cause some damage I would not want to deal with at this stage of a build. I use a clamping caul that has 3 points of controled clamping pressure to the bridge, works fine. One day I may step up to a vacuum system.

Mike
White Oak, Texas
Author:  RussellR [ Wed Aug 02, 2006 2:30 am ]
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Just for the record I just started using Vacuum too, but I was intrigued as I never thought about using a go bar deck for this, I think Michaels point is a very valid one as I was messing around with an old body today and with no support underneath the bridge area sinks like crazy under the load of the go bars.
Author:  Michael Dale Payne [ Wed Aug 02, 2006 2:42 am ]
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I don't use go-bars for this but I do use go-bars to glue backs and tops on. In theory it would be less dangerous than the backs and tops as there are less rods required therefore less chances of an oops. That said I don't think I would like to do this this way as I like to be over the top of the box with good elbow and head clearance when I align the bridge and snug dowm the clamps. The way my go-bar deck is the lighting is a little bit limited and I would worry my self to death on the alignment.
Author:  Sam Price [ Wed Aug 02, 2006 3:07 am ]
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There's NO way I am going to use go-bars for the bridge...being thicker and wider than say, a brace or a top, I would need more glue, hence the high chance of minute slippage during drying.Sam Price38931.5067708333
Author:  Howard Klepper [ Wed Aug 02, 2006 3:34 am ]
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Howard Klepper38931.5240162037
Author:  Todd Rose [ Wed Aug 02, 2006 4:26 am ]
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There are various ways to deal with the alignment issue and slippage prevention. I just wanted to point out that it is a valid method; at least one great builder with decades of experience under his belt does it this way; it works. If I recall, we used 3 or four go bars (very hefty go bars, as I said) and cauls. With six novices doing this in the class, there were no accidents and no problems.

For now, though, I'm sticking with my vacuum clamp for bridges.
Author:  RussellR [ Wed Aug 02, 2006 5:04 am ]
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Hey Howard What did you say ?

Hesh you are right from my brief experiment this afternoon without support the top does distort , but I was using 6 fiber glass rods so maybe a bit ott.

On the alignment issue I use alignment pins and I am setup to go as I have a short open time with the hide, so this wouldn't be an issue, I love Vacuum myself, but I am always open to alternatives, I really liked John Halls bridge clamp, and only changed to Vacuum because I changed to hide glue and wanted an even quicker method.
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