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Bridge gluing issue
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=28177		 Page 1 of 1
Author:  Bailey [ Mon Jul 12, 2010 12:32 pm ]
Post subject:  Bridge gluing issue
I have a different top sound hole design on a 14 fret OM sized steel string Sitka top. I have 2-2 1/2" upper bout soundholes on either side of the neck and one smaller 2 "soundhole about 2 " under the fingerboard. That smaller soundhole edge is approx. 3 " from the front of the bridge.
Dilemma: my bridge clamps are too long to go through the small soundhole and set directly under the bridge for clamping. The sound hole is also to small to use a multitude of my other regular clamps. I can't get a block under the bridge as support for clamp either....unless I can make my hand and arm the size of a 2 year old. I'm working on a potential homemade clamp that will have the block support attached to clamp that will be inside the body. It will swivel, so I can put the end of the clamp thru the soundhole and then swivel it perpendicular to fit into the bridge support area. Luckily, I haven't glued the top on yet, so I can MAYBE get a workable clamp built and test before doing the deed.
QUESTION: If this swivel clamp thing fails the equal and sufficient bridge clamp pressure in testing, is it possible to actually successfully glue the bridge on prior to gluing on the to
???. I can set stop seats on the top with the sides so it will not slip side to side or front to back during glue up. Seems like I should be able to get the bridge in correct position. Neck is a bolt on. If things go a tiny bit awry, I suppose I can widen the saddle slot for a wider saddle if necessary for additional set up ability. I realize I will have top sanding/finishing issues with it attached....so pre top prep will be necessary and extra care in routing bindings so as not to dent/scar any area near the bridge and masking off bridge during spraying.
The other option might be to create a in box bridge support from back to top that can be inserted somehow and actually clamp the bridge on using a cross member from the sides and downward pressure and shim bridge down with the inside blocking to support the top. Z Problem will again be having a block that can be inserted through the small sound hole in probably 2 pieces and able to get it into position, seated properly and out again.

Any other luthier ideas????
Looks like a fine mess I got myself into....Ollie

Kent Bailey
Author:  Yukon [ Mon Jul 12, 2010 12:39 pm ]
Post subject:  Re: Bridge gluing issue
A vacuum bridge gluing fixture will work perfectly.
Author:  SteveSmith [ Mon Jul 12, 2010 12:53 pm ]
Post subject:  Re: Bridge gluing issue
Yukon wrote:
A vacuum bridge gluing fixture will work perfectly.


There is a tutorial about building one in the tutorial section.
Author:  Corky Long [ Mon Jul 12, 2010 1:04 pm ]
Post subject:  Re: Bridge gluing issue
One creative solution would be to pre-drill the holes on strings #1 and #6, then thread a long screw through each (probably with a protective caul in the inside, and outside, to prevent marks). A couple of wingnuts tightened on the screws, and you've got a functional clamp.
Author:  Joe Beaver [ Mon Jul 12, 2010 1:54 pm ]
Post subject:  Re: Bridge gluing issue
Corky Long wrote:
One creative solution would be to pre-drill the holes on strings #1 and #6, then thread a long screw through each (probably with a protective caul in the inside, and outside, to prevent marks). A couple of wingnuts tightened on the screws, and you've got a functional clamp.


I like the sound of that! Good idea. I just might consider that for my guitars even though I use regular sound holes and typical clamping techniques. (except I do drill the 1st and 6th pin holes first for guides)
Author:  woody b [ Mon Jul 12, 2010 5:36 pm ]
Post subject:  Re: Bridge gluing issue
I've refinished a couple Tacoma Chiefs. The have an offset sound hole, and you can't get a clamp to the bridge. I put a jack inside the guitar under the bridge plate, then install the bridge with hot hide glue, and hold it tightly for 10 minutes. I still let it sit a minimum of 24 hours before stressing it. The person I learned from as a kid used this method on all his guitars. I've considered it for all of mine, but 10 minutes seems like hours when you're standing there holding a bridge.
Author:  Kathy Matsushita [ Tue Jul 13, 2010 1:22 am ]
Post subject:  Re: Bridge gluing issue
I had exactly this question today....I'm going to be building a Kasha baritone ukulele, and the soundhole is too small for me to easily position a clamping caul for the bridge. So, today I emailed Matt Blacka over at the Australian/New Zealand Luthiers Forum, since he had successfully built such an instrument. Here's what he suggested — a simple idea that had never even occurred to me (duh):

"The process for clamping with the bridge clamps will be to make a caul that fits onto the bridge patch and has notches to go around all of the braces (this will be made once the soundboard is finished, but before the body is assembled). When I clamp my bridges I use two locating pins inserted into the outside string holes to keep the bridge in place and stop it wandering. I will probably use the two inner string holes to initially pass through some pieces of fishing line that I will then attach the clamping caul to. I will then pull the fishing line back up through the soundboard/bridge, so that it pulls the clamping caul into position on the inside of the uke. I can then put in the locating pins in the outside string holes of the bridge and do up a clamp on the hole thing. Once the glue dries on the bridge, I can remove the locating pins and pass the fishing line back down through the soundboard and retrieve it through the side port hole."

Sometimes (no, often) the simplest ideas never occur to me.....

Maybe this will work for you....

Edit....I just realized this doesn't really answer your problem about not having clamps the right length to reach your soundhole....Sorry....but it might help with another idea about how to easily position and get a caul to stay inside until you can clamp it......
Author:  Colin S [ Tue Jul 13, 2010 2:57 am ]
Post subject:  Re: Bridge gluing issue
I build classicals fitted with a full brass tornavoz and therefore have no access at all to the inside of the box for clamping a bridge in place. This is no problem if you ensure a perfectly fitting bridge, high clamping forces are not needed with HHG just firmly being held in place. I use a piece of wood clamped to the neck pressing on top of the bridge centre with just a couple of cam clamps lightly snugging the wings down, these press against a baton on the cradle not against the guitar back. Classicals of course have a neck angle that facilitates this, but it should be easy to add packing at the nut end on a steel string to make this angle. I now use this method on my non-tornavoz classicals as well.

Image

Colin
Author:  valleyofelah [ Tue Jul 13, 2010 9:59 am ]
Post subject:  Re: Bridge gluing issue
Go to the LMI website and look up the fox bridge clamp. I had the same issue on a guitar a while back and I built one out of a scrap of maple and a few bolts and wing nuts. It worked perfectly. Just make sure you put some cork or leather inbetween the bridge and the outside bolts so you don't mar the surface of the bridge.
Author:  Laurent Brondel [ Tue Jul 13, 2010 12:35 pm ]
Post subject:  Re: Bridge gluing issue
It looks to me that no forearm over 6 years old can get inside your soundbox to place cauls, clamps or anything else under the bridge location.

I hope you didn't forget anything important in there…

I'd consider precisely fitting the bridge to the top radius and gluing it with HHG and hand pressure, that's the manly solution. Or go the vacuum route, where the bridge needs to fit exactly anyway, as vacuum does not have the clamping power of clamps.

BTW why the central tiny soundhole when you have soundholes in the upper bout? And a sideport…
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