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Regarding questionable long standing building practices, I'll add yet another.

Why do factories and small builders persist with saddle slots manufactured 90 degrees to the top?
Any bellying of the top or bridge rotation produces a saddle leaning forward. saddles leaning back will remain straighter, reduce bridge splitting, and are self compensating as action is raised. The whole bridge saddle system can be made lighter as well.

Anyone feel like 90 degree saddles hold advantages other than tradition?

I'm guessing the only advantage is ease of manufacture. Pretty easy to slide a bridge across a router table,
Mike

I'll add why not mill the saddle slot after the bridge is glued on AND angle back a bit?

Greg?

This seems to be a recurring theme, ease of manufacture overtrumps some better ideas.... sadly....

Could you explain how the self compensation works?

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Cause not everyone has the kajillion dollar Collins saddle mill?

Because I don't enjoy butt clenching moments or procedures all that much when there's a perfectly good alternative?

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

A couple of pieces of tape and one can angle the saddle with basic 8th grade mathematics, when pushing the bridge through a router table or table saw for that matter. Save your money. Tape is cheap!

Andy

As an angled back saddle is raised, the string break point moves back instead of forward, somewhat offsetting the need for more compensation as action is raised. Same going down.

"the string break point moves back instead of forward"

That's what I thought you meant, but I'm not understanding why more compensation would be needed if action is raised.

Maybe I'm not thinking about this correctly, but for a 90 degree saddle if you increase the saddle height to increase the action, then the string length between the nut and the saddle break point increases ever so slightly because it is the hypotenuse of a right triangle. Wouldn't that mean that the break point on the saddle would need to be shifted ever so slightly toward the nut to correct for the added length to maintain the scale length and the proper intonation? If that's correct, then increasing the height of an angled back saddle would be moving the break point in the wrong direction since it would make the nut-to-break point distance even longer than raising the height of a 90 degree saddle.

Do I have the geometry wrong?

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

The higher the string off the frets, the more it is stretched sharp when fretted and the further south the break point must be moved to compensate.
I think it was Allan Carruth who figured 9 degrees of back angle would be completely self correcting as action was raised or lowered on a typical steel string. Any amount of rear tilt is at least going in the right direction.


Edit: I just re-read your post and get what your saying

I think the tiny change in length as the string sweeps on the end of a 25.5" radius is insignificant compared to the increased sharpness from stretch as the action height goes up.

Speak for yourself, Some thing are so obviously the answer

Aha! That makes sense. I wasn't thinking about the increased string stretch caused by fretting. The self-correction is a pretty cool feature. Thanks.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

JSDenvir wrote:
Hesh wrote:
I'll add why not mill the saddle slot after the bridge is glued on AND angle back a bit?

Greg?

Cause not everyone has the kajillion dollar Collins saddle mill?

Actually you can make a simple jig out of scraps of wood that will allow you to mill the slot with the bridge glued in place, and have the slot either tilted back or at 90 degrees. With a little practice a standard laminate trimmer can be "plunged" into the bridge to start the slot and fiducial marks made to delimit the ends of the slot. Two or three passes can be made to rout to the final depth needed.

How much does the bridge rotate? Trevor Gore says to aim for 2 degrees. Should we build in an angle for the point when the guitar develops a belly? Or do we build for the top as it leaves the shop? Or split the difference?

"Should we build in an angle for the point when the guitar develops a belly? Or do we build for the top as it leaves the shop? Or split the difference?"

Ideally the top will "pull up" a little bit when the guitar is first strung up and then not "belly" further. If a guitar develops a significant belly over time it was probably too lightly built.

Dave Farmer. Implicit in your initial post is the assumption that there's something inherently wrong with milling a saddle slot at 90 degrees. I disagree with that premise. I'm one of those "small" builders who persists in doing just that. 've had no problems at all with that set up. I have access to several guitars that I made from 1980-'82, and there have been no structural or intonation problems due to my saddle slots. In fact, for the past 6 years I've gone to 3/16" and 1/4" saddles and still have had no bridge splitting even with the increased amount of material removed. So, I consider in my case "If it ain't broke, don't fix it."

Also, regarding tops developing a belly. Not even my earliest customers have reported any noticeable deformation of the top, that you seem concerned about. I think I have to go with Clay on this one; "if a guitar develops a significant belly over time it was probably too lightly built." or perhaps it's a true flat-top rather than one that has an arched X-brace.

At any rate, if you feel it necessary to angle the saddle back, by all means do so. At least one notable luthier, Paul Woolson, does. But, I'll stick with what works for me.

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michael propsom
www.propsomguitars.com

After 50 years using 90 degree saddles with zero complaints or problems I am cool with it. I am sure tilted saddles work well but I am not about to change -- but this caught my eye:



How's that work?

Thanks

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Ken Cierp

http://www.kennethmichaelguitars.com/

I don't understand the self compensating features of angled saddles. While the builder I am working with uses both square and angled saddles, he sees the advantages of the angled saddle as a reduction in loading on the upper forward treble edge of traditional Martin bridges at the cost of some minor movement in compensation points on the saddle as the instrument ages.

When I mentioned to him that the design was thought to be self compensating, he asked whether we had ever reduce saddle height on an older instrument to maintain the player's desired string action heights, and how desirable it might be to that player to see the intonation change over time as the instrument aged and further reductions in height were needed. I was stuck for an answer and opted to retreat to the student bench to ponder the point.

In thinking about this, the movement in intonation points on an angled saddle is only a benefit of the design when changing string action over a limited period of time, such as for initial setup. It seems to me that intonation change is an undesirable attribute where the action adjustments occur over time due to the normal aging of traditionally constructed instruments, no?

My building guide notes that the traditional 3/32" and 1/8" width saddles used on many guitars have very limited compensation capability - something like 5/100ths and 7/100ths of a semitone, respectively, and that reasonably angles of tilt on the saddle have limited impact on compensation when bridge roll (I laugh at that - white or wheat?) is taken into consideration.

Could someone correct or confirm my thinking here with some analysis? Assertions are all very well, but I prefer to argue these points with my boss with something more in my pocket than my good looks, wits, and wiles.

Once again, my apologies for the length of this post - I realize that pushing through more than 2-3 paragraphs of my writing is stiff work, but I really want to understand the arguments made here.

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A constellation only takes shape when one maps the whole.
- Beth Brower

If you have a system that works great. I agree there is no point fixing something that works. But like you I am drawing on my experience. A large percentage of instruments I see have saddles that are straining and transferring the strain to the bridge. For many it becomes a real problem. I think it's un-necessary. A small change in design seems so simple and effective, I don't understand why it's not more common.
The title of my post is not a totally rhetorical question. I listed a few advantages of tipping the saddle back and asked if anyone had a reason not to do it. So far I've heard from people insisting they don't have any problems. I have not heard anyone list an advantage of the 90 degree saddle other than it's faster to make. This thread is an off shoot of one questioning what common or historical building practices continue to be followed to the detriment of instruments. In general, 90 degree saddles I see as one of them. My question still stands, why not just tip it back?

I think the problem here is that we have an assertion -- and perhaps even a straw man. Is there "real data" indicating that "one", this design element is an issue either for set-up or repair problems and "two" tilting back the saddle eliminates these issues. Perhaps the Taylor and Martin repair guys can chime in regarding warranty claims on the four hundred or so guitars that are produced daily by these two companies alone.

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Ken Cierp

http://www.kennethmichaelguitars.com/

I'll concede a 9 degree saddle is the far end of the spectrum.
In your example wouldn't the ideal be to have the saddle remain tangent to the strings as much as possible?
If normal bellying and saddle lean add up to a couple of degrees of rotation, I think a saddle tipped back a couple of degrees initially would be remain closer to tangent over time.

I just took a quick glance at the thread, and didn't see that anyone has mentioned what Bruce Petros has been doing for years. Use the link to see how far his saddle leans back.
http://petrosguitars.com/wp-content/upl ... ayer-1.jpg

I don't have many customers come to me and ask me to raise their action

It does happen but very rarely.

The use of the word "tangent" is not correct here. A tangent is a line that just touches the edge of a circle and is 90° to the diameter of the circle that touches at the same point as the tangent. What should have been said is the saddle should equally split the string break-over angle.

However, the problem I most often see with factory made guitars with saddle issues is not that they were constructed at 90°, but that the saddle slot is sloppy resulting in the saddle leaning forward.