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PostPosted: Mon Jun 13, 2016 10:26 pm 
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Walnut
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Hesh, any chance we can see some pictures of your bridge rabbet process?

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PostPosted: Mon Jun 13, 2016 11:53 pm 
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Brazilian Rosewood
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This topic has been discussed many times on this forum and a search will yield good information. I have used a routed ledge for many years after seeing it here, I believe from David Collins.

StewMac base with a radiused surface to match the top. I use a 1/8" bit and a wood post that I can bring the bit up under. The width is usually around 1/32-3/64. I do test routs for depth until the ledge just barely clears the finish. usually around .003-.004"

Many other methods that I am sure work equally well in the hands of those comfortable with them.

Image

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These users thanked the author Terence Kennedy for the post (total 2): James Orr (Thu Apr 13, 2017 1:32 pm) • Hesh (Tue Jun 14, 2016 6:33 am)
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PostPosted: Tue Jun 14, 2016 6:42 am 
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Old Growth Brazilian Rosewood
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JBoogie wrote:
Hesh, any chance we can see some pictures of your bridge rabbet process?

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Sure but Terry beat me to it.

We do it just as Terry does and it works great. A small detail that's huge once you experience it that may be getting missed here is that "pocket" that is created in the cleared finish that matches the rabbet. Snap fit with bridges is a beautiful thing!

Is it necessary? No

Have great guitars been built without it? Absolutely

Why do it then? Because this technique offers the most available wood-to-wood gluing area without.... clearing finish to the bridge perimeter AND it will not show now or in time with cold creep, differential expansion, RH swings, etc. It's a great method and we use it on very nearly every bridge that we glue on or remove and reglue. The only exceptions are guitars with very thin oil finishes with no film thickness.

One last thing for now. The traditional method of having the flat bridge bottom span the finish ledge makes for no wood-to-wood contact for some distance inward from the finish ledge. Say the finish thickness is .004 at the ledge draw it out on paper and see where with clamping and distortion the wood-to-wood contact actually occurs and you may be as much as 1/4" inside the perimeter.

On the back edge of the bridge, where the heavy lifting is done this is potentially problematic in time and with less than ideal care.

We like it because it works great and we have a decade of experience and data doing it this way now.


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PostPosted: Tue Jun 14, 2016 9:12 am 
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J De Rocher wrote:
SteveSmith wrote:
I used to just bevel the edge but now cut a rabbet with the razor blade clamped in a split dowel thing I spoke of earlier. I also think the rabbet is the way to go.


Do you have a photo of your tool? I'm having a hard time picturing exactly how it works.


I'll take a picture tonight and post it.

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These users thanked the author SteveSmith for the post: J De Rocher (Tue Jun 14, 2016 2:52 pm)
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PostPosted: Tue Jun 14, 2016 9:33 am 
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Koa
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Quote:
One last thing for now. The traditional method of having the flat bridge bottom span the finish ledge makes for no wood-to-wood contact for some distance inward from the finish ledge. Say the finish thickness is .004 at the ledge draw it out on paper and see where with clamping and distortion the wood-to-wood contact actually occurs and you may be as much as 1/4" inside the perimeter.


Ditto!

Having the bridge sit on top of the finish coating (lifting it off the primary gluing surface) is bad news. So unless you have a precise pocket and a perfect matching bridge (factories now do this with CNC machining) good joinery practices dictates the need for relief around the bridge perimeter.

As a side bar I've seen some fairly high end imports with bridges that popped of where the was no attempt what so ever to duplicate the bridge shape with proper masking or pocketing -- a strip of tape was apparently placed in the general bridge area, when removed that was the primary glue surface-- good enough -- not!

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PostPosted: Tue Jun 14, 2016 4:16 pm 
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Koa
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Not a great photo.
PC laminate trimmer with a brass dowel in place of the roller and a piece of tape hiding it. Various tape types give quick small adjustments to rabbet size.
Attachment:
IMG_3014 - Copy.JPG


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PostPosted: Tue Jun 14, 2016 5:58 pm 
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J De Rocher wrote:
Do you have a photo of your tool? I'm having a hard time picturing exactly how it works.


Jay, here is the little tool. I plan to make a thicker scraper blade for it. The razor blade works ok though. Not as good as a laminate trimmer jig but it will get the job done. If you look close you can see the rabbet on the cutoff next to it.
Image

Edit: Machine screw fit is tight and its pinned at the bottom to keep it all lined up.
Image

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These users thanked the author SteveSmith for the post (total 4): Bryan Bear (Tue Jun 14, 2016 9:42 pm) • Clinchriver (Tue Jun 14, 2016 6:09 pm) • bcombs510 (Tue Jun 14, 2016 6:07 pm) • J De Rocher (Tue Jun 14, 2016 6:05 pm)
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PostPosted: Tue Jun 14, 2016 9:44 pm 
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Brazilian Rosewood
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That's great Steve. Nice and simple, basically a scratch stock. One could make something like this with any piece of too steel (broken bandsaw blade, razor blade, scraper. . .) in short order. It could even be made to work scraping bindings after the color coats!

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These users thanked the author Bryan Bear for the post: SteveSmith (Wed Jun 15, 2016 6:00 am)
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PostPosted: Wed Jun 15, 2016 5:59 am 
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Scraping bindings was its original purpose.

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PostPosted: Wed Jun 15, 2016 9:16 am 
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Quote:
Do you have a photo of your tool?


Oh boy....There's a Brett Favre joke in there somewhere..... laughing6-hehe

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PostPosted: Wed Jun 15, 2016 1:01 pm 
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Mitch Cain wrote:
Quote:
Do you have a photo of your tool?


Oh boy....There's a Brett Favre joke in there somewhere..... laughing6-hehe
[clap]

Or, an Anthony Weiner joke, perhaps.....

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PostPosted: Wed Jun 15, 2016 1:18 pm 
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Brazilian Rosewood
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SteveSmith wrote:
Scraping bindings was its original purpose.


I'm going to make one of these with thicker steel (than a razor blade) and square sides. This might be a good way to refine binding and purfling rabbets instead of a file. I always have trouble working the file into the concave waist area. . . scraping might be better as long as you are careful to go downhill with the top and back grain.

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