cutting lacquer for gluing on a bridge

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Mike Ryan
Posts: 153
Joined: Sat Apr 28, 2012 2:11 pm

cutting lacquer for gluing on a bridge

Post by Mike Ryan »

I have always had trouble scoring em6000 lacquer without chipping it badly or wandering all over the place.
Always wanted to get closer to the actual bridge outline but was afraid to do so.
I tried something different this time and got good success.
I tried using some blue tape around the outline and some thin fastcap double stick tape (very very thin double sided tape) to hold a plastic draftsman's triangle. Worked great. the draftsman's triangle seemst to keep the lacquer from pulling up.
Also got a bent chisel from woodcraft which made the chiseling of the cut lacquer go well.
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Ed Haney
Posts: 13
Joined: Sat Jan 07, 2012 7:58 pm
Location: Sugar Land, TX USA

Re: cutting lacquer for gluing on a bridge

Post by Ed Haney »

Just curious, have you ever tried to apply finish over .001 Frisket film to avoid edge build-up?

Extra Tack – A .001" matte polyester film with a strong adhesive to help prevent paint seepage and edge build up. Ideal for use on cold press (rough) board, glass, plastic, metal or applications requiring more exact color control. http://www.grafixarts.com/product/Frisket_Film
Steven Smith
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Joined: Fri Jan 06, 2012 5:01 pm
Location: East Tennessee

Re: cutting lacquer for gluing on a bridge

Post by Steven Smith »

Ed, I've heard of others using Frisket - are you using it?
Joel Nowland
Posts: 86
Joined: Sat Jan 07, 2012 6:01 pm

Re: cutting lacquer for gluing on a bridge

Post by Joel Nowland »

You shouldn't have to use a router at all. Lacquer/solvent resistant tape works fine. This is how I do it.

-Route a 3/32" wide relief around the bottom of the bridge the depth of the guitar's finish thickness.
-Clamp the bridge in it's proper position on the guitar top and drill and taper fit all six pins (plastic pins) leaving them a little high.
-Remove the bridge clamps and tape around the bridge which is held in position by the bridge pins.
-Remove the bridge from the guitar top leaving a taped outline of the bridge on the guitar top.
-Stick a 2" wide piece of lacquer tape down on a piece UHMW or something the tape will release from and accurately trace the outline of the bridge on the tape.
-With an x-acto/craft knife, cut 1/16" inside of the bridge tracing on the lacquer tape.
-Peel of the lacquer tape bridge cutout and stick it to the guitar top a uniform 1/16" inside the area taped on the guitar top.
-Peel of the the tape used to outline the bridge on the guitar top.

You are ready to spray.

When you are done leveling and buffing the finish, simply free hand cut 1/64" to 1/32" wide of or rather outside the lacquer tape on the guitar top and peel of the tape.

Glue the bridge on using the six plastic pins to hold the bridge in position. I started doing it this way about 60 guitars ago and it works great.
Mike Ryan
Posts: 153
Joined: Sat Apr 28, 2012 2:11 pm

Re: cutting lacquer for gluing on a bridge

Post by Mike Ryan »

Wow,
sounds complicated.
I don't build enough to be that complicated.
I am going to stick with what I noted above.
I know a very well known builder (40+ years - sells all he builds) who has introduced me to the well known KISS method. I admire you builders who can have that many steps and methods in something like bridge placement and be successful at it.
I have to deal with reality for me and it does not lead me toward the more complicated methods.
Thanks for the tip though, Joel. Always interesting to see how others do things. .
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Peter Wilcox
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Location: Northeastern California

Re: cutting lacquer for gluing on a bridge

Post by Peter Wilcox »

Joel's way of masking the bridge area sounds faster and cleaner than removing the lacquer once it's on, and actually is pretty simple. But how do you route the relief around the bridge (I don't have a router table)?
Maybe I can't fix it, but I can fix it so no one can fix it
Joel Nowland
Posts: 86
Joined: Sat Jan 07, 2012 6:01 pm

Re: cutting lacquer for gluing on a bridge

Post by Joel Nowland »

It sounds like a lot of steps but it is actually easier than routing off the finish. I have done both ways.

You don't need a router table, just a small router or laminate trimmer held in a vise or make an extra large router plate for your router and attach it to the edge of a bench.

Use a 5/8' or larger flush cut router bit or a rabbiting bit with an undersized bearing to get whatever width of relief you want.

Make an arched/radiused plate with a hole in it that's just big enough for your router bit to extend up through and attach it to your router plate. The arch matches the bottom arch of your bridge and/or guitar top.

Then you just have to carefully adjust the router bit up through the hole until it's removing the amount you want.

Joel
Ed Haney
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Joined: Sat Jan 07, 2012 7:58 pm
Location: Sugar Land, TX USA

Re: cutting lacquer for gluing on a bridge

Post by Ed Haney »

Steven Smith wrote:Ed, I've heard of others using Frisket - are you using it?
Steven,
The reason I asked is that I have not used it, but I am considering using it on my current build. I bought some from Hobby Lobby the other day. I was wondering what others' experience are with it. I have used regular painter's tape and, like other folks, hate to deal with the edge build up.

I see how Joel's method would work for a very good clean glue up. But the 3/32" wide strip around the bridge is glued to finish (if at all) and therefore not really considered for holding the bridge to the top (the remainder of the bridge, other than the 3/32", would be all that I would count on to hold the bridge to the top). So the 3/32" becomes extra bridge weight to hide the glue joint (would look great). Extra weight for the strings to drive is something that I want to avoid. I recognize that this is very debatable since some folks believe a larger bridge (heaiver) will make to a better sound. I think that sustain and volume (responsiveness) is imporved with less weight to start the bridge/top moving and keep it moving.

Ed
Mike Ryan
Posts: 153
Joined: Sat Apr 28, 2012 2:11 pm

Re: cutting lacquer for gluing on a bridge

Post by Mike Ryan »

I actually had almost not lacquer buildup last time, used the really thin blue tape and scraped more over it when I sanded every 3 coats and it ended up even.
Ed Haney
Posts: 13
Joined: Sat Jan 07, 2012 7:58 pm
Location: Sugar Land, TX USA

Re: cutting lacquer for gluing on a bridge

Post by Ed Haney »

Mike Ryan wrote:I actually had almost not lacquer buildup last time, used the really thin blue tape and scraped more over it when I sanded every 3 coats and it ended up even.
Mike,
From your original post I did not think that you had put anything down during finishing. I thought you were scraping lacquer off the entire top's bridge surface. So I am not sure I fully understand your method. Are you applying a reduced size (slightly small than the bridge) piece of tape and finishing over it? And then outlining with a razor and scraping the thin line of lacquer?

Ed
Todd Stock
Posts: 394
Joined: Tue Feb 28, 2012 7:57 pm

Re: cutting lacquer for gluing on a bridge

Post by Todd Stock »

Done this a lot of different ways, but currently making up a 1/4" MDF template, rout with 1/4" downcut spiral and 3/8" OD bushing. Usually just a .005-.006 deep rout to get to clean wood. Advantages are speed (once the template is made for a particular bridge, just clamp in place and rout) and less opportunity to damage the top. Disadvantage is template (20-30 minutes for something like a belly bridge) and getting the template properly located. Masking also works well, but have to be careful to avoid cutting the wood and keeping the finish corners either radiused or otherwise unstressed.
Michael Lewis
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Re: cutting lacquer for gluing on a bridge

Post by Michael Lewis »

You really need to avoid scoring the wood around the bridge. Fine to score the finish but not the wood, as it creates an opening in the fibers that can lead to the bridge pulling off wood. Much safer to rout the area clear, as Collings and others do. Their finish is .005" so they rout .007" deep, which is JUST enough to get clean wood.

If you are only doing this once or twice a year then continue doing it by hand but if you will be doing it more frequently by all means make a routing template for whatever shape your bridge is. Routing the bridge patch is quicker, cleaner, more predictable, and less likely to cause damage, though you must be ever vigilant to do no harm. As always.
Mike Ryan
Posts: 153
Joined: Sat Apr 28, 2012 2:11 pm

Re: cutting lacquer for gluing on a bridge

Post by Mike Ryan »

Maybe do the router thing at another time. I only build 3 guitars a year and this last technique I used produced no marking of the wood while scoring the lacquer. I actually don't score the lacquer very deep and it still pulls off fine with the tape.
Have built about 15 so far and still learning, learning, learning but seem to be improving. I don't do it for a living and don't plan to so I can do anything however I want to and can listed to myself as well as you more experienced luthiers. It has to be fun and engaging or I don't want to build instruments. If I try to adopt too many new techniques over too short a period of time I just make a mess. Also, simpler if better for me as I have said.
Thanks for all the discussion though. I find this forum helpful don't want it to be too helpful.
I am glad luthiers don't run medical schools or we would have 500 ways to do every procedure and some techniques would work out great and others would just feed the lawyers.
Joel Nowland
Posts: 86
Joined: Sat Jan 07, 2012 6:01 pm

Re: cutting lacquer for gluing on a bridge

Post by Joel Nowland »

Mike is right.

You don't cut through the lacquer, you just score it well. The lacquer comes away at the score line when you peel up the tape.

Joel
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