New Racing Bridge

[Bob Connor]

I've been fiddling around with bridges the past few days as per the pics I threw up in another thread.

Most of the woods I'm trying are local desert hardwoods which are very dense and incredibly heavy.

With the standard shape that we use, a lot of these these bridges are finishing up around 40 grams. Way too heavy for the way we build.

I try and shoot for around 25 grams.

So after some research and a fair bit of head scratching on how to reduce weight I re-contoured the curve edge, brought the wings in and reduced the width by about 5mm.

The effect of reducing the width means that the bridge saddle will be closer to the bridge pins so the string break angle will be greater thus there should be more volume and a bit more bite in the top end.

It was interesting how changing one design element lead to a potential improvement in the design. (remains to be seen/heard I guess but the theory is essentially sound)

The upper bridge in the pic is made out of Gimlet (Eucalyptus sp. I think), weighs 40 grams and is our original design.

The lower bridge is Bendee (Acacia catenulata) weighs in at 28 grams and is the new, sleek racing model.

Theses two are sanded to 2000 and buffed with Menzerna compound.



Bob

[Craig]

I reckon the light model looks better than your older model Bob. Really Swish !



Cheers , Craig

[Bob Connor]

Makes the old on look chunky, eh.

One of the wings on the old one isn't finished properly either.

I was in a hurry to finish it, weigh it, then get to the pub.

[Paul B]

I prefer the new one too.

Good to see a man who has his priorities sorted.

[Allen]

I've made a couple out of Cooktown Iron Wood and they have come out at 40 - 45 grams. I've been scratching my head at a way to get them down to at least the low 30 gram mark. Looks like you came up with the goods.

[Kim]

I made the one in the image below a while back out of Malga. As Bob suggest, this is heavy wood. To get this bridge down to 32 grams, I had to shorten and thin the wings as he has done. In fact the wings are now down to around 1/16" thick, but being Mulga is incredibly stable.

Even with that knot you should notice on the treble side wing, it is strong. Because this is just a prototype, and I muffed it by mis-aligned the "D" string bridge pin hole, I even tried to snap that wing off using moderately heavy pressure as judged by a ham-fisted half tanked yobbo and found that it easily resisted my well lubricated half-brained efforts. When this bridge is radiused on the bottom, I am hoping it will come in at around the 30g mark. If it does, I may even use it on the R&D special

I realy do like Bob's idea of creeping a bit off the back though, but moving the pin holes toward the slot to increasing the break angle may be off the cards for this one, but the next is a done deal, great work thanks Bob



Cheers

Kim

[Hesh1956]

Bob I always liked your first bridge and the shape of a fish but the second one is even better.

Your theory is all what I subscribe to also, greater break angle etc, so I am sure you will have a better performing bridge now.

Any inclination to angle the slot back say 6 degrees or so, that is my next step on my next redesign.

Very nice work my friend!!!

[Ron Wisdom]

I like the new, smaller model better, too. What is the length and width?

Ron

[Allen]

How much smaller a footprint would you say it is now? Any worries about gluing surface?

[Allen]

Any inclination to angle the slot back say 6 degrees or so, that is my next step on my next redesign.

Very nice work my friend!!!

What way would you angle the slot Hesh, towards the pins? What does this hope to improve?

[Hesh1956]

Allen - yep angle it toward the pins. It helps the saddle resist being pulled forward by lessening the disparity in the string angles in front of and behind of the saddle. This can also have the dividend of lessing the possibility of the bridge cracking from the pull on the saddle.

A number of builders do this but often won't talk about it. There is also a belief, I don't know if this is true though, that the downward force on the saddle is more distributed making for better vibration transmission to the bridge from the saddle.

Regardless, mechanically it is a good practice and with some bridge designs it will increase the break angle to the pins too by moving the top of the saddle back toward the pins.

[Bob Connor]

I was working on a Cooktown Ironwood one yesterday as well Allen.
That is very heavy stuff.

I've taken a further step with that one in reducing weight by by angling the whole top of the bridge from where the saddle is back towards the the curved area. It plays havoc with getting the lines straight where the wings meet the body of the bridge so I'm still working on that.

Kim I actually did the opposite and moved the saddle toward the bridge pins. I'd already got all the blanks cut out in the old shape so it was much easier to to take the 5mm off the straight side on the linisher.

The angle is definitely the next step Hesh.

We don't put the saddle slot in until the bridge is on the guitar to make sure the intonation is correct.

Allen the angle is to put the pressure directly down through the bridge rather than have the forward leverage effect that the string break gives.

The new bridge dimensions are 143mm (5 5/8") wide and it's 35mm (1 3/8") at the widest part.

I did a search on the OLF for "Bridges" and had a look at as many different styles as were there and pieced together the comments.

The one that stood out was one of Mario Proulx's bridges (and also the comments that he made).

Here's a pic of it. Note the width and the string break angle.



That's only about an inch wide and Mario builds guitars for bluegrass players who generally string their guitars with fencing wire (56-13)

Bob

[Allen]

Boy, that really is close. I had sort of given up on the idea of Cooktown Iron Wood and some other odds and ends of local wood that I've got hiding in the corners simply because of the weight. I think that I'll knock one or two out this weekend and see what comes of it.

[Bob Connor]

Brigalow is another Queensland wood you might look at too Alllen.

Not quite as heavy as the others.

[Craig]

I'm pretty sure it was Alan Carruth that said anything greater than a 45 degree downbearing has no additional affect on the bridge.

A tailpiece design however is a completley different matter


Cheers Craig

[Hesh1956]

When I was really into bridge designing trying to find my own way Scott VonLinge really helped me a great deal.

He is a believer in eliminating any humps, bumps, sharp angles, and excess mass. He makes his living essentially sanding the excess mass off the bridges of factory guitars and shaving braces.

Below is one of my prototypes, this one is MadRose.

Although I prefer a bridge to be between 28 and 35 grams there is nothing that says that it has to be. For heavier bridges you can use stiffer tops and vice versa for lighter bridges. The trick though is to do the bell curve thing so that your own bridge design(s) can be used with your own particular bracing/building styles.

This one below is 18 grams and still not slotted so it will probably come in at 16 grams. I may use it too one day but on something like an O or OO sized guitar that would need to weigh 3 pounds or less and have a very thin top.

[Bob Connor]

.

Although I prefer a bridge to be between 28 and 35 grams there is nothing that says that it has to be. For heavier bridges you can use stiffer tops and vice versa for lighter bridges. The trick though is to do the bell curve thing so that your own bridge design(s) can be used with your own particular bracing/building styles.

This one below is 18 grams and still not slotted so it will probably come in at 16 grams. I may use it too one day but on something like an O or OO sized guitar that would need to weigh 3 pounds or less and have a very thin top.

Hesh - what do you think the effect would be if you used the 16 gram bridge with a much thicker and heavier bridge plate to compensate for the lightness of the bridge.

You have to look at the whole enchilada methinks as once the components of the top are assembled you have an entire system that needs to be considered.

This is one thing that I wrestle with a lot.

From what I understand a lighter bridge/bridgeplate system will have less sustain in the bottom end, will yield a more immediate response and will accentuate the highs. (this also depends on the impedance characteristics of the wood being used)

The heavier system will yield nice sustaining bottom end at the expense of highs.

So it really is a juggling act to balance the sound that you are after.

I really think that the bridge plays an enormous part in determining the voice of the instrument.

Bob

[gratay]

I like the fish since its been on a diet a lot better, Bob.
very nice lines now

[Hesh1956]

Bob I completely agree with ya M8 on all counts. I have posted on the other forum often that I consider the bridge AND the bridge plate to be like a hot dog bun An enchilada is the same way of thinking and this leads me to the conclusion that we are both hungry...

You can through in the weight of the saddle too and consider that the hot sauce or mustard. It is indeed a system, a salad of sorts so yes I think that I could use the very light bridge with a heavier bridge plate and get similar results to using a heavy bridge and light bridge plate.

The bridge and plate material are every bit as important as the top material too in my view.

[kiwigeo]

Bob I completely agree with ya M8 on all counts.

Hesh mate, youre sounding more like an Ozzie everyday!!