Help needed - bridge saddles

[David Houck]

This may have been discussed before; in fact, I may have asked this question before.  I broke another string (TI Jazz Rounds) at rehearsal Sunday.  It seems to me that this is happening a bit too often (especially given the cost of the TI's).  The strings are breaking right at the saddle; D's and G's.  Each time after this has happened, before putting on new strings, I've gently sanded the edge of the saddle, hoping to eliminate any rough spots that may be contributing to the breakage.  I anchor my thumb on the bridge pickup and thus play right at the bridge when using finger style.  And I do play with a wide range of dynamic attack, which means quite often I do use a lot of force.  I do not want to change string brands, I love my TI Jazz Rounds; and I do not want to change the way I play.  I'm hoping the solution is in the saddles.  I'm thinking of ordering new saddles from Alembic that are completely rounded.  I'm also wondering if having the saddles plated would help keep them smooth.  And I'm even wondering if maybe raising the tailpiece might help by reducing the angle of the string at the saddle.  After all, my bridge is higher than where a lot of other folks have theirs set at.  Any thoughts??

[bob]

How about some photos? A nice side view so we can see what the break angle looks like (taken from the G side), maybe a super closeup of the string exiting the saddle on the neck side, and perhaps also the bridge side. And of course, a closeup of the saddle itself, right after breaking a string (or at least before more sanding).
 
You don't really want these things to be rounded. Ideally, the saddle should be a half circle that perfectly fits the string, with full contact on the neck side (you can be a little sloppier on the tailpiece side.
 
Any chance that your slots are just too wide, or perhaps a little narrow?

[mica]

Usually if a string is repeatedly brreaking right at the saddle, it's either a burr on the saddle or the string manufacturing itself. Back in the early days of Alembic we used Pyramid Gold strings. We supplied an extra G string, because as good as they sounded, they always broke.  
 
Do your saddles have V shaped slots or U shaped slots.

[bsee]

Wouldn't the string angle over the bridge saddle matter here as well?  If the bridge were high relative to the tailpiece, the angle would be more severe.  I would think that would make it easier to break strings.  Maybe one of those extremely attractive ebony shims under the tailpiece might help?
 
-Bob

[mica]

If the height was really extreme (imagine the bridge a foot above the surface), it could be a contributing factor, but the angle doesn't really change that much across the adjustment range of the bridge. After consulting with my dad, he agrees that this change in angle doesn't seem significant.
 
Unless the rails of the bridge have been modified, if you raise the bridge very high, the strings will lay right on them. You can use anything under the tailpiece as a test shim if you want to keep the bridge height but reduce the angle off the anchor.  
 
James recommends that sandpaper may not be getting to the burr (try and see if you can feel it with your fingernail). Try filing with a small round needle file.
 
Echoes to Bob's photo requests. Also, please send us one of the broken strings - we might learn something from it.  
 
One last thing: when you say the strings are breaking too often what interval are we talking about?

[David Houck]

A testament to my lack of photography skills.  

 

 

 

 

 

 

[David Houck]

Oh, and one of the angle.
 

[wideload]

Dave-
 
If the strings are breaking too often, maybe try putting on a new string instead of the old shortened one??! (How often do they break? Just once!)
 
Larry

[David Houck]

Bob Novy; I just reread your post and now realize I didn't get the pics you were asking for!  Well, after waiting around all afternoon for the camera batteries to recharge, it only took me an hour and a half to get the pics that I did !!
 
Mica; I agree, the angle doesn't seem extreme.
 
I like the needle file suggestion.  I'll half to make a trip into town and see what I can find at the hardware store.  Is there any particular size I should look for?  The slots seem very small for a file!
 
I hope the pics that I did get are useful.  It doesn't look like I got close enough to determine whether or not there is a burr.
 
It feels smooth to my finger.  And looking at it with a magnifying glass, it looks pretty good.
 
To answer Bob's question about snugness, it looks like a pretty good fit.
 
As to frequency; after reviewing available evidence it may be the case that I was exagerating.  I was thinking this was the third break in about 6 months but it was only the second.  I was mistakenly including a break on one of my other basses.  So it would appear the strings are lasting about 3 months.  I would guess I practice an average of 30 minutes a day (not nearly enough ) with a rehearsal once every couple of weeks lasting an average of maybe 5 hours.
 
So, am I overreacting??

[bsee]

Well, from that photo, I would discount my thoughts on the angle.  It doesn't look particularly severe at all.

[David Houck]

Larry; tying them in knots was causing a lot of fret buzz!!

[David Houck]

I guess one reason it seemed like they were breaking too often is that I've had the same problem with my Essence 4 and my Spoiler.
 
Mica, the Essence is in your shop and you may want to glance at the saddles on it if it's any help.  Although it does seem that by sanding the Essence saddles I did eventually get it to the point where it quit breaking.  Come to think of it though, I never did use TI's on the Essence before I shipped it to Santa Rosa.
 
With the Spoiler, there's only been one break; and that set lasted maybe six months of normal use.
 
So, maybe I am overreacting!!

[mica]

This part looks a little suspect:
 

Is the little ledge I think I see there in real life?
 
When the string is in place, this might wear over time at this  concentrated point, that will cause more weakness and eventually a break.  
 
From the top picture, it almost looks like the string is wearing on the leading rail - is that the case?  
 
I was looking around Thomastik's website and this was on the front page:
 
When to change strings
A string's component materials will eventually become fatigued. This is particularly true for the string core. The richness of higher partials and fullness of tone become degraded. First and foremost this happens with intensive amounts of playing. To avoid sound quality loss we strongly advise changing strings at appropriate intervals. Changing single strings instead of the whole set at once, i.e. mixing old and new strings, will jeopardize the entire tonal balance of the instrument.
 
--
 
Since it is the core that broke, it may be considered normal. I sent a message to Thomastik-Infeld and will let you know when I receive their response.

[sfnic]

That's what occured to me, too, when I saw the pics.  The leading edge of the saddle looks to have a relatively sharp--not an edge, per se, but a change of aspect between horizontal and vertical.  It doesn't look like there's a burr there, but rather that the top-to-face corner is fairly sharp.
 
It also looks like the string isn't resting on the bottom of the groove, but rather contacts the groove walls up about 1/4 string diameter on each side.
 
The drop-away angle of the saddle top also looks like it may be steeper than the actual string angle back to the tailpiece.  If so, then the string isn't being supported all the way across the saddle, and instead is resting on the front lip, as mica points out.  
 
From the wear pattern in the saddle, it looks like the string contacts the saddle for about three wraps, then the saddle top begins to fall away from under the string.  It also looks like the saddle groove is not quite in alignment to the string; both the first and second pictures show that one wall of the groove is flat while the other is rounded.
 
I think the main cutting edge pressure point is about 1/4 string diameter up on the front edge of the notch, just about exactly where mica's arrow is.  In her picture, you can see about three string windings embossed in the saddle on that side, and a pretty clean fulcrum point at the face.
 
If that _is_ the break point, it's a little tricky to fix.  If you file that point of the groove to round-over the lip, you move the apex of the saddle backwards somewhat.  Then you start to introduce saddle rattle possibilities.  A _very_ fine needle file should be able to round that front edge over; the idea is to change the groove contour to allow the string to contact the saddle along the entire bottom 1/2 of its diameter, while moving the apex point from the exact edge back no more than about 1 winding width.
 
Smoothing out the winding embossing will also help a bit.  Also, relieving the lateral pressure on the back end of the string, where the saddle groove prevents it from running straight to the tailpiece will also help.  Carefully widen the back end of the groove on the screw side of the saddle to relieve the cross-grove tension on the string.
 
 
Looking at the string itself supports (to my mind) the idea that the string isn't resting completely on the bottom of the groove.  I think there's a pinching action going on between the contact points on each side of front lip that's putting extra pressure on the core.  The winding embossing in the saddle also suggests a lot of pinch pressure which, coupled with the extra pressure introduced by the groove-to-tailpiece misalignment, could be what's stressing the core.
 
Finally, the front edge of the bridge frame looks like it's got some string wear on it, which is odd, as the side view picture indicates there's plenty of clearance.
 
That side view also shows that the down-angle from the bridge to the tailpiece is not too severe; that shouldn't be causing any problems.  Shimming the tailpiece would most likely result in a slightly looser feel on the strings, but probably wouldn't affect the breakage problem.
 
nic
 
(Greeting all, btw.  I'll swing over to Introductions a bit later and post a howdy over there.)

[David Houck]

Hi Nic; welcome, and thanks!
 
I looked some more with the magnifying glass and lamp at the edge where Mica's arrow is pointing .  When I came back to the computer and read Nic's post, what I had been looking at seemed to correspond with what he was describing.  The edge at the face on the left side of the groove, where Mica's arrow is, does not appear to be even.  And it does seem that, as Nic has suggested, that the string may be rubbing on a high point such that it is not resting smoothly on the bottom of the groove.  Given that, what Mica has suggested seems reasonable, that the wear is being concentrated at that point.  However, I must admit that it takes a lot of looking with the magnifying glass for me to see the unevenness.
 
Both Mica and Nic mentioned that the front rail looks like it may have string wear.  This does not seem likely; the other three strings do not touch the rail when pushed down in an abnormal fashion.  However, I've only owned this bass for about seven months, so this wear may predate me.
 
The quote from the TI site that Mica provided (thanks!) talks about tone degradation.  And this may be part of my thinking the strings are breaking too soon.  Because, to my ears, the strings still sound great!!
 
I've reread Nic's points several times now, and I think I understand everything he is saying.  And though I don't think of myself as someone who is skilled in doing fine detail work of this nature; if I can get the right tool, I'll give it a try.  I must admit though that it does sound difficult!
 
I'm wondering where I should go to find a very fine needle file.  My first searches on the web have uncovered some promising leads.