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Bridge width.
http://www-.luthiersforum.com/forum/viewtopic.php?f=10101&t=47510		 Page 1 of 1
Author:  Colin North [ Thu Mar 24, 2016 5:16 am ]
Post subject:  Bridge width.
Making a BRW bridge (SG around 0.87, belly type) and I'd like to keep the weight down.
Trevor Gore says he feels uncomfortable using less than 45 square cms area, but doesn't mention the width, front to back.
What's a reasonable minimum width?
Author:  kencierp [ Thu Mar 24, 2016 6:48 am ]
Post subject:  Re: Bridge width.
Many fine sounding guitars around (very old and very new) with simple and pyramid bridges measuring 1" x 6"
Author:  Hesh [ Thu Mar 24, 2016 7:07 am ]
Post subject:  Re: Bridge width.
Check out Mario P's very cool instruments - he uses a pretty small bridge.

Fitting well, exploiting very nearly the entire area of the bride, micro-rabbiting, and HHG proper technique can all go a very long way in keeping a very small foot print bridge on board and sounding great.

My own bridges are something that if I build again will be changed. I originally went for appearance and now having been in the repair world appearance is pretty low on the priority list. Instead I want decent gluing area, considerations of break angles, considerations for serviceability in the future meaning nothing about the bridge that would come apart when heat is applied, and low mass for the four letter word, tone, that I rarely talk about. :) Other considerations are where common commercially available USTs will come out and not interfere with he X, etc.
Author:  kencierp [ Thu Mar 24, 2016 7:51 am ]
Post subject:  Re: Bridge width.
Main point being ---- 1" x 6" = 38.7 sq.cm
Author:  Ben-Had [ Thu Mar 24, 2016 8:44 am ]
Post subject:  Re: Bridge width.
Typical belly bridge between 51-52 sq/cm.
Author:  meddlingfool [ Thu Mar 24, 2016 10:43 am ]
Post subject:  Re: Bridge width.
I've been using 1x6 for over 100 guitars in the last few years, seems to be working, but all of the bridge is touching...
Author:  Tom West [ Thu Mar 24, 2016 1:25 pm ]
Post subject:  Re: Bridge width.
As Ken says..................1"X 6" is also what I've settled on and they end up around 25 grams depending on thickness and wood species. Have gradually worked myself down to this after starting with a standard belly bridge. Have only done 3 with this figures and have 4 on the almost completed bench with this size. I'm feeling comfortable.
Tom
Author:  tjp [ Thu Mar 24, 2016 3:03 pm ]
Post subject:  Re: Bridge width.
I have settled on kind of a modified belly bridge, with the belly 1/8 in wider than the wings. I like the look, but maybe I just have issues with commitment one way or the other...I do like knowing that I have a little extra glue area on the back of the bridge.

I sometimes wonder if I should make the bridge 6 1/2 long to be able to either move the X further forward or feel more comfortable with a wider splay. Or both....
Author:  Rod True [ Thu Mar 24, 2016 3:20 pm ]
Post subject:  Re: Bridge width.
If you like a belly bridge but want to keep the weight down you can always reduce mass off the back side of the bridge. I've been making mine like this the last few guitars and they are coming in at 19.8 grams. This one is cocobolo.

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7703_10154027623433783_7453924907996400044_n.jpg
Author:  DennisK [ Thu Mar 24, 2016 4:01 pm ]
Post subject:  Re: Bridge width.
Rod True wrote:
If you like a belly bridge but want to keep the weight down you can always reduce mass off the back side of the bridge. I've been making mine like this the last few guitars and they are coming in at 19.8 grams. This one is cocobolo.

Very nice [:Y:] That's what I do as well. It also helps spread out the stress at the back edge of the bridge, since the thin part can flex some.

As for the actual topic of this thread, I'd say probably around 2cm. But 2.5 to 3.5 seems to be the typical range.
Author:  Colin North [ Thu Mar 24, 2016 4:28 pm ]
Post subject:  Re: Bridge width.
Great stuff, thanks guys. I had looked at typical pyramid bridges, 1 x 6 or so as several people mentioned.
I've worked out that I should be able to make one with this BRW weighing in at about 24 or slightly less grammes, 160mm about 2.5/3.0 mm thick wings, 34 mm wide, 160 long, wings about 3mm less than the belly part (tapered at the back)
Gives me a good 45mm square cms gluing area I think and target weight.
Making the bridge rabbeting fixture now but may have to go with TB as I'm not sure I have the confidence with HHG yet.
Author:  bcombs510 [ Thu Mar 24, 2016 5:26 pm ]
Post subject:  Re: Bridge width.
Colin, I'm sucking wind on trying to make a bridge rabbeting fixture. I have the Stewmac Dremel base, which I've seen some use. I can't make out how to deal with the underside of the bridge being radiused at 30'. If you have success and could share that would be greatly appreciated.


Sent from my iPhone using Tapatalk
Author:  Colin North [ Thu Mar 24, 2016 7:29 pm ]
Post subject:  Re: Bridge width.
No worries Brad, I'll post pics when I get it done, tomorrow should be.
I'm doing something similar to one in this post (in principle) http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=46531&hilit=bridge+rabbet, just using a Proxxon router I have doing nothing.
With your top radius, you radius the wooden table (fixed to the dremel router base) to 30' in your radius dish.
Author:  Alan Carruth [ Fri Mar 25, 2016 11:07 am ]
Post subject:  Re: Bridge width.
The belly bridge was devised to reduce the maximum peeling stress along the back edge, which is the thing that determines how long the bridge will stay put. That stress is largely a function of the length of the glue line along the line of pull; that is, of the bridge width. Martin apparently had problems with the bar bridges coming up after they started offering steel strings as an option. They were toothing the bottoms of the bridges, which reduces the strength of the glue bond; if you don't do that they can work, as Mario as shown.

I'm not a big fan of micro-rabetting, as it only reduces the effective width of the glue line and introduces a stress riser right where you don't want one. It's not so hard to score around the bridge carefully and remove the finish all the way out to the edge by whatever means.

I do taper the bridge thickness behind the saddle to reduce the weight, and can get a belly bridge down to less than 25 grams easily with the usual woods. If you go to something like walnut you can make the bridge outline even larger and still keep the weight down. This is good on things like cedar and redwood tops, where the further reduction in peel stress along the back edge is helpful, give the low peeling resistance of those woods.
Author:  Colin North [ Fri Mar 25, 2016 11:12 am ]
Post subject:  Re: Bridge width (+bridge rabbet pics for bcombs510)
Here you go Brad, seems promising, how you getting on?
Used an edging guide came with a Makita or Colt laminate trimmer.
Fine adjustment by a bolt underneath bearing on a brass plate epoxied to the router (Proxxon one is totally useless.)
Tested it on an old cracked OLFSJ bridge.
Author:  Rodger Knox [ Mon Mar 28, 2016 2:53 pm ]
Post subject:  Re: Bridge width.
Guitar bridges are a piece of cake. Try a tipple bridge, ten steel strings and a 1"x5" pinless bridge!
Author:  Colin North [ Mon Mar 28, 2016 4:30 pm ]
Post subject:  Re: Bridge width.
Say what?!
Attachment:
pikasso guitar.jpg
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