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Taylor 410: Bridge Reglue


1. A Taylor 410. This guitar was manufactured in 1995 by Taylor Guitars. The design of and materials used on the 410 have changed over the years. This guitar has an ebony bridge without any holes for bridge pins.	2. A Lifting Bridge should be reglued. If it is not reglued both the bridge and the top of the guitar can sustain serious damage. See those small holes through the back of the bridge? Those are where the strings go through. The holes are counter-sunk in order to both hide and catch the ball ends. This is actually a pretty clever bridge design that, in my opinion, both en- hances the tone of the guitar and prevents the bridge plate from sus- taining damage due to contact with the ball ends of the strings.


3. Scoring the Finish Around the Bridge. This is necessary because the finish actually goes about 1/8" under the bridge around its perimeter. This is a common way of gluing a bridge by the major manufacturers. Contemporary Taylor bridges are actually microrouded on their under- side perimiter in order to create a better glue joint between the bridge and the top.	4. Softening the Glue with a Heat Lamp takes about 7-10 minutes. The heat shield is protecting the fin- ish on the top of the guitar. The glues used during guitar construction by the major American manufacturers will soften when exposed to high temperatures. It's always a good idea to use a glue's weaknesses to your advantage when taking apart a musical instrument.


5. Removing the Bridge with an Artist's Spatula. I'm starting disassembally from the back of the bridge. The top of this guitar exhibits a fair amount of run out. Since grain run-out can cause the spruce to splinter, I'll do the majority of the disassembally with the spatula going with the runout.	6. Cleaning the Glue off of the Spatula must be done between each entry into the glue joint. The glue can actually compress the finish and soft wood on the top of a guitar as the tool enters the glue joint. Cleaning off the spatula with a razor blade only takes a second because the glue is still soft from the heat.


7. Cutting the Locator Pins is done with a thinned and sharpened putty knife. This putty knife actually works well for removing bridges too. Since the locator pins used by the factory to keep the bridge in position during gluing are made of a soft plastic, they are readily cut. I only cut the locator pins after I've severed the glue joint by working the artists' spatula all the way around the bridge.	8. A Cleanly Severed Glue Joint. Where the artists' spatula severed the joint with the grain runsout on the top of the guitar the glue tends to stick to the spruce. This is due to the fact that adhesives do not stick well to endgrain.


9. A Saddle for Securing the Bridge. I've put a tight fitting, new tusq saddle into the bridge. This will give me a surface for our shop's wood carver's vice to clamp to so I can clean up and shape the bottom of the bridge.	10. Clearing the Old Glue from the bridge is pretty quick, safe and easy with a sharp chisel. I'm being very careful so I do not cut the ebony.


11. Shaping the Bottom of the Bridge. The saddle does a good job stabalizing the bridge while I contour the bottom of the bridge to fit the top. I start this process with a block plane with a sharp iron. Since a flat top guitar is under 180 or so pounds of string tension, the bridge typically becomes somewhat distorted. This means that I must reshape the bottom of the bridge to insure a good fitting glue joint to the top of the guitar.	12. Checking the Bridge Against a Straightedge. Since the top of this guitar is somewhat bowed from 12 years of string tension (as all used guitar tops become) I want to make the bottom of the bridge a touch bowed as well. Rather than fitting the bridge to match the top of the guitar, I like to make the arch of the bridge (from end to end) meet the arch of the top half way. This insures both structural stability and a preservation of the guitar's tone. Forcing the top of an acoustic guitar flat at the bridge can have the opposite effects.


13. Checking for Straightness From Front to Back. I only want the bridge slightly concave from end to end, not from front to back. A block plane does a pretty good job of shaping the bottom of the bridge but I inevitably have to do a bit of spot scraping guided by a straightedge to fine tune the glue joint.	14. Spot Scraping the Bottom of the Bridge is guided by the straightedge. I'll scrape all of the high spots (from front to back) down with the scraper as a final touch.


15. Scoring the Bottom of the Bridge improves the strength of the glue joint.	16. Clearing the Glue from the Top of the Guitar. I like to do this with a chisel, but a scraper or razor blade also works.


17. Final Shaping of the Top of the Guitar. A scraper will get rid of any high spots in the spruce or little bits of glue that the chisel missed. I typically remove about .005" of the spruce during a bridge reglue. This insures that I've scraped away any oxidized spruce as well as an adequate amount of the old synthetic glue that found its way into the spruce's pores.	18. Scoring the Top of the Guitar.


19. A Custom Clamping Caul. I made this caul specifically for re- gluing Taylor dreadnaught bridges of this era. There are 2 deep notches cut into the poplar caul to accomodate the cross braces by the bridge plate. The two smaller raised sections have mahogany stock capping them to make up for the added thickness of the bridge plate at the center of the caul. This caul is slightly concave to match the bottom of the bridge..	20. Heating the Bridge for Gluing. I'll be gluing the bridge with hot hide glue because hide glue won't creep like alaphatic resin glue does. Hide glue only has an open time (time in which it can be clamped) of about 10-15 seconds. Heating the parts to be glued increases the glue's open time.


21. Applying Hot Hide Glue to the Bridge. I've heated the glue in a double boiler. I prefer to use hot hide glue for just about all load bearing, wood to wood glue joints. Hide glue is superior to alaphatic resin and polyvinyle glues for instrument repair because it creates a stronger glue joint, is easy to dissassemble and doesn't creep. Though inferior to hide glue for guitar repair/construction purposes, A.R. and P.V. glues are quicker and easier to use than hot hide glue which is why these synthetic adhesives are used by the major guitar manufacturers.	22. Cleaning up Glue Film with a Damp Towel. Since hide glue is water soluble, a lightly dampened towel will easily remove any glue film from the finish and the bridge.


23. All Done. A meticulously fitted joint glued with hide glue ensures that this bridge will stay put for a good long time. I made the saddle on this guitar taller than usual because it's owner plays lots of bluegrass and likes the dynamic versatility that high action permits (he plays really hard!).	24. A Reglued Bridge with a new bone saddle has this guitar playing better than ever!