• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Thunderbird Club

#136,962
Chucky Stiletti said:
if I understand your post correctly; an increasing force B will augment force C enough to pull out the (over 1" long) inserts from the body if dimension A is shortened?....I think the neck will warp before that..
View attachment 3634183
Click to expand...
Keep in mind that the inserts are friction inserts. The only thing holding them in place is the degree of bond they have with the wood body. Anything you do to weaken that bond increases the likelihood of the insert pulling out. You do not need to pull the insert out an inch to cause the bond to fail, you just need to break the bond. Once the bond is broken the bridge failure is set in motion and may go very quick or very slow.

That bond can be broken by torque or tension (I suppose compression or impact could also do it but it would be rare that that happens). Torque from overtightening the bolt (easiest to do by not loosening the strings before adjusting the bridge height) or Tension from the strings would be the two most common causes of bond failure. As you lower the front of the bridge you shift the upwards pulling force of the string tension more towards the back bolts.

If you'd like to test this, loosen your strings, lower the front bolt as low as it will go, then raise the back bolts as high as they will go (I know, no one would ever set up their bass like that, but we're trying to exaggerate the condition to speed up the failure) now bring the strings to proper tuned tension. You will have significantly more force pulling up on the rear studs than when the rear is lower. The suggested lower rear and raised front slightly changes the direction of force to more of a shear force and less of a lifting force. The friction inserts are a very good fastening method for shear force but less so for pulling or lifting forces.

How much pulling force is too much force is impossible to predict due to variations in wood quality, hole size, tightness of the friction fit, humidity, age... you name it.

You might have a real nice tight insert fit and a relatively stable temp/humidity environment and never have a problem regardless of how flat the bridge is set. Or you might have a sloppy insert fit from the factory and a very dry climate and be more prone to failure.

It's all a bit of a crap shoot. My advice, raise the front bolt to create a better break angle for the strings. Any advantage you get on reduced rear insert stress is an added benefit. And if the inserts should ever fail it's a pretty simple fix with some wood glue and toothpicks to tighten the hole back up and reset the inserts.

Glenn Johnson said:
Keeping the front post a bit higher also gives you a better break angle. Just saying.
Click to expand...
:thumbsup:This is the number one reason to do it, everything else you gain is just added benefits.
 
  • Like
Reactions: Engle, Glenn Johnson, Miles_ONeal and 7 others
#136,964
Is the center block on a 2013 Thunderbird the same width as a 60s or 70s? I'm looking into having pickup rings made and since none seem to exist off the shelf for a 2013, I need measurements. Chucky kindly got me them for the pickups themselves, but I need to know that they wouldn't go past the edges of the center block. I've seen ones that say 3-15/16" (100mm).

Edit: I measured 4-1/16" wide.
 
Last edited:
  • Like
Reactions: Glenn Johnson, Count Bassie, GBassNorth and 4 others
#136,966
Butcherboy said:
....someone obviously disliked my testing of the new Lollar pickups for my Precibird...

View attachment 3634621

...maybe I took the wrong decision to order the split coil overwound preci pups instead of a pair of thunderbird pickups, but I ordered this one instead for the same price (always wanted a slothead...)

View attachment 3634624
Click to expand...
Gots to see that EB-0 when it's done.:drool:
 
  • Like
Reactions: Glenn Johnson, MCF, Count Bassie and 6 others
#136,969
PillO said:
Ok, I did a little back of the envelope vector math. With a total pull on the strings around 100lbs and a break angle of about 15°, it is a pull around 25lbs on the two posts (12 lbs each). But I did all this in my head without looking up any data. And it has been many years since I did any vector math, so be suspicious.
Click to expand...
Giving this a little more thought (far more than it deserves), I think my mental back of the envelope calculations were too simplistic. I failed to account for the fulcrum at the front bolt. I was thinking only of the string break over the saddles. To better analyze the dynamics, I think I need to draw a diagram (and I am not going to do that). But I will say that the quick and dirty mental math I did is probably close to reality; close enough for the discussions here.

Any mechanical engineers here can put their degree(s) to some use and do the actual calculations. Because what else are you going to do? Practice?
 
  • Like
Reactions: Engle, Glenn Johnson, Miles_ONeal and 7 others
#136,970
BklynKen said:
Is the center block on a 2013 Thunderbird the same width as a 60s or 70s? I'm looking into having pickup rings made and since none seem to exist off the shelf for a 2013, I need measurements. Chucky kindly got me them for the pickups themselves, but I need to know that they wouldn't go past the edges of the center block. I've seen ones that say 3-15/16" (100mm).

Edit: I measured 4-1/16" wide.
Click to expand...
why are you looking to add ring/s?
 
  • Like
Reactions: Engle, Glenn Johnson, MCF and 4 others

Latest posts

Top Bottom
Back