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Sometime back, folks posted their ideas for adjusting the bottom of the bridge to account for finish thickness. The one I was interested in used a laminate router, but I cannot find it. So, I'm looking for ideas on this issue. I want to cut (reliably) a shelf edge arround the bottom of a bridge to account for finish thickness.

Thanks,

Mike

I use my Bosch Colt with the roller edge guide. I made a mini router table for it from MDF. Shaped the surface of the MDF in my radius dish to match the contour of the bridge bottom. I use a scrap piece to dial in the depth and width of cut, then go to town. Nothing fancy, but totally efficient and does a great job.

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sweat the small stuff.

This is my rig. StewMac router base with a radiused platform. I think David Collins showed it here 5 or 6 years ago. I copied it.



I prep the top and rout a trial on a small piece of scrap and make sure it just clears the finish ledge.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I believe John Hall has a youtube video on this

Sent from my GT-P3113 using Tapatalk 4 Beta

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Under Compensated Nut!

Todd, what kind of bit are you using?

Bump for router but type

I made the bearing guide from a wood dowel glued to the arm so I can bring the router bit up under it. (1/8" downcut) I like the clamped wood finger, simpler is always better. We all have a tendency to over think stuff!

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Thanks. I was using a spiral down cut as well. Just wanted to be sure.

Mike

I've never heard of this before. Am I right in thinking that rather than scrape the laquer back to the exact outline of the bridge you leave a thin line of laquer that overlaps the bridge "foot print". And what we are talking about in this thread is routing off a ledge around the bridge that fits ontop of the laquer?

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We are all in the gutter but some of us are looking at guitars.

I've been scraping my bridges to relieve the edge which is not all that accurate and leaves more gap on the edge after gluing. It's not a large gap but this will improve that for sure. Time to go find yet another laminate trimmer - I really like having the trimmers dedicated to one job; just makes it go so much quicker.

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Steve Smith
"Music is what feelings sound like"

Another trick related to this is to position the bridge (I like to pin it through the saddle slot) and then lay green tape around the perimeter on the top right up to the edges of the bridge. Two layers makes a nice locator guide. Then Johnson's wax the tape and the side edges of the bridge. Any glue squeeze out comes off with the tape afterwards. Makes easy clean up and no glue scraping, etc while gluing up.

FWIW,
Alan D.

Radiused base and adjustable fence.
Cuting a .004 deep rabbet, finally a job perfectly suited for the ol'Dremel!

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Pat

Hmmmm, I'm a bit concerned about the amount you undercut Todd. All we are trying to do here is just make sure that the line where we cut the finish doesn't show so only a very little bit needs to be undercut. You say it is 1/16' but looking at your photo it look to be about 3/32+" or 4-5mm, right. Doesn't that leave kind of a small footprint for the actual glue attachment? I try to keep mine to about 2mm, just enough to cover the line.

I actually like your cool spruce scrap, very direct solution!

Alan D.

This idea of applying a wax to the surfaces where u don't want glue to adhere interests me. I've thought about it before. My thoughts were along the line of using a crayon to apply such a layer. Very interesting.

Just when I thought I has all the jigs and techniques covered as I approach the end of my first build- this comes along! Now I'm thinking "how do I do this?".
I've been following the Cumpiano book, as I'm sure you all know, he just scrapes off the finish.
So, if I'm going to rout into the top .005", should I be using a template for that? Do people do it freehand? Any advice or links to tutorials greatly appreciated.

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We are all in the gutter but some of us are looking at guitars.

Thanks for the follow up Todd, just looked real wide in the photo, probably like horses noses looking six times as large in a photo

I use fish glue and still like to do the paste wax thing around the edges. It is just so much easier to pop off the crystallized glue with the tape.

Joe, I just do it freehand. I lay down the green lacquer safe tape over the whole area. then position the bridge and draw around the edges marking onthe tape. Then I go inside that line 1/16" or 2-3mm and draw another line. I mark through with an Xacto knife and lift off the tape in the center revealing where I need to route. I then go at it with a dremel, or in my case an RDX, and a 1/8" down-spiral milling bit. Check out http://www.mscdirect.com/browse/?searchterm=1%2F8%22+milling+bit&hdrsrh=true for bits. I start in the center and set my depth to just see the wood and then rout it all out freehand up to the tape. I usually follow that by scraping with a glass microscope slide to get right to the wood. I follow that with a wipe of solvent, lacquer thinner in my case, using Q-tips. That gets me right to the wood without cutting into much of the wood fibers. You really don't want to cut the wood around the perimeter, so careful with the Xacto not to go very deep. That can weaken the top wood at the edge of the bridge, not a good thing. Just use the router to go down to the wood.

You can see some photos of the process on http://dunwellguitar.com/BuildGuitar/BuildGuitar9.htm, but don't follow the bit about using the dremell directly to freehand cut the perimeter on the bridge, I now use the same system mentioned in this thread by all the other folks.

FWIW,
Alan D.

I'm positive using a router to take off the finish is ok, but I can do it with a razor blade in about 15 minutes. Some things are ok by hand. But, I can see how this would work. As with many things Todd suggests, I usually come around to his way of seeing things, eventually. What slows me down is my belief in my current abilities.

I appreciate this information on the router method of removing finish, though I too am currently doing it by hand. I'm using the method Bob Gleason describes on his site (Thanks, Bob!). It's here: http://www.pegasusguitars.com/lacquer_r ... foot1.html

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Tim Allen
"Never hurry, never rest."

I know I'm a little bit late to the game here, but I wanted to show a few pictures of my rig. It's not terribly different than the others, but here it is, nonetheless. As I mentioned earlier, radiused the base in my radius dish. I radius the bridge before I route the ledge, which gives consistent ledge depth. The roller guide is a standard Bosch item and I also use it with my Williams binding jig. Easily adjustable. Anyway, here are some pics. And just for fun, one of a Mad Rose bridge going on a 12 fret OM, if I can ever get the finish completed. (I know, Todd. If it has 12 frets, it's not an OM. But it's an OM shape and it joins the body at the 12th.)

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sweat the small stuff.

Has anyone had any problems with flying bridges when using this method? It seems illogical at first glance, since glued joints are most likely to fail at the edges. Adding an intentional stress riser there in the interest of a good neat job seems counterintuitive. I suppose in practical terms it may be a non issue.

I dont think this is really a worse stress riser, which is generated by
a sharp notch or abrupt change in cross section. The abrupt stop of
the glue bond at the vertical edge of the bridge would, I believe, be
a greater stress riser than the edge of the bond under the routed bridge,
where some glue squeezes into the routed area. And there are a lot of
guitars out there done with this method. The Luthier community would
be aware if a lot of these were failing...

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain