Official Luthiers Forum!
http://www.luthiersforum.com/forum/

removing a bridge by routing ? how's it done?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=24085		 Page 1 of 1
Author:  jackwilliams [ Wed Oct 07, 2009 11:38 am ]
Post subject:  removing a bridge by routing ? how's it done?
I have a bridge to remove on a repair job, and I have seen posts indicating that some route the bridge off rather than using heat.
Could someone elaborate or direct me to a post where the overall procedure is explained ?
I am very timid on trying this procedure as I don't want to get into the top or the finish.

best regards,
jack
Author:  Laurent Brondel [ Wed Oct 07, 2009 11:51 am ]
Post subject:  Re: removing a bridge by routing ? how's it done?
You need to bolt two rails under your router base. Hardwood scraps are ideal, wax the bottom. Make sure the rails are higher than the bridge, taking into account the dome shape of the top, and that they're spread enough to allow the bit to reach the front and back edges of the bridge. If you use a trimmer you'll have to make a larger base out of ply or plastic.
Chuck a large (and sharp) straight bit in your router and stick masking tape on the top around the bridge to protect the finish from the rails. Take light passes and check carefully after each pass until all you have left is a sliver of the bridge. That can be removed with a sharp chisel, bevel down, being careful to go with the grain (runout) of the top, and inverting for the other bookmatched half.
Author:  woody b [ Wed Oct 07, 2009 12:02 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
I recently saw John Hall (Bluescreek) remove a bridge by working his way around it with a chisel. He lightly tapped the chisel around the edge of the bridge for 4 or 5 laps, and it came off cleanly, with no damage to the top or the bridge. I've always used heat, but his method worked great.
Author:  jackwilliams [ Wed Oct 07, 2009 12:37 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
I have an LMII bridge heating blanket that I have used for other bridge removals basically the same one I saw in Frank Fords website; I have already tried it on this bridge, but there seems to be some trauma... not a lot, but some trauma on the top , which I believe has been caused by heat.
I had read at some time about folks routing not only an old bridge, but new finish as well, and I have considered routing this bridge off, I just wasn't able to find the post where it was referenced from.
Many thanks to Laurent, Woody and Filippo for your replies; I'm still a little squeemish at this point,
best regards
jack
Author:  bluescreek [ Wed Oct 07, 2009 6:31 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Pulling a bridge isn't that difficult . You can expect to see some wood fibers lifting , that isn't going to be that bad. Here are a few ways to pop off a bridge . If you use heat , you have to protect the top around the bridge. You need to get the glue seam to about 160 degrees to get the glue to fail. I am not a big fan of using heat if I don't have to.
My favorite method is with a chisel , I grind the chisel to 80 degrees and tap lightly around the chisel. The purpose isn't to split the bridge off the top but more to cause a shear to the glue . Once the glue fails by the shock it lifts pretty easily. I did demonstrate this very technique at Jim Hall open house 2 weeks ago. The top and bridge were unscathed . I just did this with a D41 in my shop for a lifting bridge . Had the strings on it within 24 hours.
My last resort is routing off. I also use a pair of parallels to work as a base and start to just rout the bridge , but I don't use a router , I use my air inlay tool. The down side is that the bridge is destroyed.
Author:  jackwilliams [ Wed Oct 07, 2009 6:49 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Many thanks John for your reply and advise,
regards,
jack
Author:  peterm [ Wed Oct 07, 2009 7:32 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
I think routing is the safest way to go about it. Heat in the center seam and adjacent braces may not be such a good idea plus the risk of getting the heat blanket somewhere unexpected.
A simple rail jig will suffice to route the bridge down to a few thou and they peel it off with a chisel.... a 5 minute job.
Author:  Alan Carruth [ Wed Oct 07, 2009 7:42 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
For those of you who view a router as a handful of screaming emergency, and who have some minimal hand tool chops, you can plane a bridge off almost as fast as you can rout it, and a lot more quietly.
Author:  george wilson [ Wed Oct 07, 2009 9:07 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
I have always removed bridges by shocking them off with a chisel.Personally,routing is not something I would want to resort to. The bridges I have removed were not glued over the finish,or had exotic glues under them. Martin bridges pop off nice and clean with a few sharp whacks of a chisel carefully applied so as to not mar the finish with the bevel.
Author:  Colby Horton [ Wed Oct 07, 2009 10:07 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
I went through this a couple months ago. I thought the routing process was pretty easy. Never tried the heat method. I'll just post pics rather than try to explain it all. Good luck!
Author:  Robbie O'Brien [ Thu Oct 08, 2009 9:23 am ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Alan Carruth wrote:
For those of you who view a router as a handful of screaming emergency, and who have some minimal hand tool chops, you can plane a bridge off almost as fast as you can rout it, and a lot more quietly.



I am with Alan. A handplane can remove a bridge fairly quickly.
Author:  jackwilliams [ Thu Oct 08, 2009 10:01 am ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Robbie :" A hand plane can remove a bridge fairly quickly."

In skilled hands, yes. I too dislike the whine of a router, and cringe at the thought of getting it close to a guitar.
I really appreciate everybody taking the time to read and reply to my questions and offer their advise or as in the case of Corby, to offer offer pictures. There is certainly more than one way to tackle this problem.


jack
Author:  muthrs [ Thu Oct 08, 2009 10:41 am ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Yes, a hand plane will work as well and it doesn't require mad skills to plane off a bridge. There must be something in the air!
Author:  Barry Daniels [ Thu Oct 08, 2009 10:51 am ]
Post subject:  Re: removing a bridge by routing ? how's it done?
I am surprised that no one has mentioned the old repairman's method of using a putty knife with a rounded over edge. This works especially well when the bridge has a lifted edge or corner. The main thing is to make sure the putty knife doesn't dive down into the grain of the spruce. You can avoid that by knowing the direction of runout, which reverses for the other side of the top.
Author:  Michael Dale Payne [ Thu Oct 08, 2009 11:05 am ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Barry Daniels wrote:
I am surprised that no one has mentioned the old repairman's method of using a putty knife with a rounded over edge. This works especially well when the bridge has a lifted edge or corner. The main thing is to make sure the putty knife doesn't dive down into the grain of the spruce. You can avoid that by knowing the direction of runout, which reverses for the other side of the top.


I am with you Barry I have removed near 60 bridges (I am guessing as I have not kept count :roll: ) and I find that a thin seam knife and a heat block works just fine. I have never had a seam joint or a brace seperate on me. I have had to touch up finish once or twice or 20 times laughing6-hehe but a heat block and a seam knife has worked fine for me for years.
Author:  muthrs [ Thu Oct 08, 2009 3:16 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Quote:
I am surprised that no one has mentioned the old repairman's method of using a putty knife with a rounded over edge. This works especially well when the bridge has a lifted edge or corner. The main thing is to make sure the putty knife doesn't dive down into the grain of the spruce. You can avoid that by knowing the direction of runout, which reverses for the other side of the top.


Barry, the reason no one mentioned this is because the initial question posed was "removing a bridge by routing? how's it done?" In attempts to answer this question, to which Laurent and Colby gave the most direct responses, no one was debating the "best method for removing a bridge." I have removed and repaired many bridges with heat and a knife, but Jack wanted to know how you go about routing a bridge off.
Author:  Colby Horton [ Thu Oct 08, 2009 11:09 pm ]
Post subject:  Re: removing a bridge by routing ? how's it done?
Also, a bridge that is already starting to lift is much easier to remove with a knife than one that is glued down fresh tight and perfect. On mine I had a problem with the bridge, but the glue joint was perfect.
The only thing I don't like about using the hand plane is when you get real close the the wood. Like when there is 1/32" left of ebony bridge still glued down tight. It gets scary for me working around the finish. With the router you can at least nibble the bridge away right down to the spruce, with the hand method it is a little scarier for me right there. And chisels can also be scary. Have to make sure one doesn't get out of control and slide into that finish. Just my .02
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/