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Post by angelodp on Nov 26, 2016 10:55:22 GMT -5
Hi, I am experimenting with using only the two outside screws on a typical strat bridge ( actually a brass one ). I want to see how the bridge operates under tension with just two screws. I am curious if others have tried this and if there are any anecdotal incidents of the screws giving way. Th body is basswood, I have reinforced the screw holes with cyano.
Yes, I do know that there are two hole variants, I just want to prove this out and see if 6 screws is way more than needed.
Ange
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Post by b4nj0 on Nov 26, 2016 11:14:32 GMT -5
It seems to me that even with the most skilled installation of a six hole bridge, only two of the screws are actually taking the strain. I have a Yamaha Pacifica 904 which has a two point vibrato. When I bought it, one of those "screws" (they are not bolts- more like countersunk woodscrews with a machined undercut) had fractured off (although it still worked fine.) I reckon that the two "screws" coped well with the shear forces but not with the previous owner's whammy bar excesses. I bought replacements from Yamaha for "peace of mind". Someone like Cyn1 would be better placed to hold forth on this, but my guess is that it should be OK, especially if you treat it more like a Bigsby than a Floyd Rose.
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Post by angelodp on Nov 26, 2016 17:13:37 GMT -5
I can concur that the two screw operation is more than adequate, and in fact perhaps preferable ( to my taste ). The instrument is a strat with twin humbuckers, bass-wood body from GF, brass trem, 4 springs, brass screws, ,010 set of strings. The return to pitch is excellent, the freq response is of a normal character for PAF style pups. I should think that it would take a force well beyond the strings and springs to tear these screws out. I may start pulling my other screws, in other strats, out. The action of the trem is quite fluid with a 1/16 offset ( rise in the rear plate ). PS the GF body is surprisingly nice and very affordable. Ange
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Post by b4nj0 on Nov 27, 2016 5:49:56 GMT -5
Try a search on The Forum. This classic vibrato design has been done to the death over the years. Lots of information squirreled away here...
I've always thought that countersunk screws (and preferably raised head for aesthetic reasons) would be better for use with a trem-leo. Certainly my aforementioned Yamaha's designers must have thought so, but they undercut the shank* which makes it weaker.
*I guess that makes them bolts after all!
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Post by Deleted on Nov 28, 2016 15:43:30 GMT -5
Hi, I am experimenting with using only the two outside screws on a typical strat bridge ( actually a brass one ). I want to see how the bridge operates under tension with just two screws. I am curious if others have tried this and if there are any anecdotal incidents of the screws giving way. Th body is basswood, I have reinforced the screw holes with cyano. Yes, I do know that there are two hole variants, I just want to prove this out and see if 6 screws is way more than needed. Ange Cyano is nothing. Don't kill your basswood like that. If you want to start experimenting you'll need maple or rosewood or any equally rigid hardwood dowels in the place of the screw holes. And then use bushing-studs. (like modern Fender design). My All-maple Carvin's floyd which has the pre-bushing/insert-stud design has collapsed the wood around it. Now just imagine what could some thinner screws under equal tension do to basswood. Brrrrrr horrible!! If you like your GF body, well keep it safe!
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teking66
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Post by teking66 on Jan 8, 2017 9:42:32 GMT -5
I tend to agree with greekdude on this.
Being a mechanical designer I can say with pretty good certainty that you will eventually destroy the body. That bridge was designed to use 6 screws, the load is shared evenly across all 6. By removing 4 of the screws you have tripled the load on each of the remaining two screws. As soft as Basswood is and as short as those screws are they will eventually wallow out those two screw holes in your body. It may take a year, maybe even three, but it will happen, and the fix for that is likely to be expensive and/or ruin the value of the guitar.
In the long run it might be cheaper to just buy a new body, or even better a whole new (or used) guitar with the bridge you want.
But, that is just my two cents.
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col
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Post by col on Jan 8, 2017 17:33:56 GMT -5
It seems to me that even with the most skilled installation of a six hole bridge, only two of the screws are actually taking the strain. I have a Yamaha Pacifica 904 which has a two point vibrato. When I bought it, one of those "screws" (they are not bolts- more like countersunk woodscrews with a machined undercut) had fractured off (although it still worked fine.) I reckon that the two "screws" coped well with the shear forces but not with the previous owner's whammy bar excesses. I bought replacements from Yamaha for "peace of mind". Someone like Cyn1 would be better placed to hold forth on this, but my guess is that it should be OK, especially if you treat it more like a Bigsby than a Floyd Rose. I tend to agree with greekdude on this. Being a mechanical designer I can say with pretty good certainty that you will eventually destroy the body. That bridge was designed to use 6 screws, the load is shared evenly across all 6. By removing 4 of the screws you have tripled the load on each of the remaining two screws. As soft as Basswood is and as short as those screws are they will eventually wallow out those two screw holes in your body. It may take a year, maybe even three, but it will happen, and the fix for that is likely to be expensive and/or ruin the value of the guitar. In the long run it might be cheaper to just buy a new body, or even better a whole new (or used) guitar with the bridge you want. But, that is just my two cents. My from my non-mechanical designer perspective, I can understand the 'logic' of b4nj0's position, but only if we assume that all the materials are perfectly rigid and perfectly non-compressible (of course, this is never the case). Otherwise we would not sense increasing tension/resistance as we tighten screws in any given situation (even with all tool steel components we would still experience gradual (albeit steeper) growing resistance/tension). I'd use all six screws, as intended, and attempt to tighten them to a similar degree (shared load).
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Post by b4nj0 on Jan 8, 2017 19:37:33 GMT -5
Well the way I see it, tightening them is not actually how they should be installed, even if you should only want to reduce string pitch. Assuming that they are not to be "tightened down", the sides of the fasteners are what take the load. Using six screws is fine, I use all six on my vibratos, but what if only the first and (say) the third or fourth are making contact? CNC bored pilot holes would be better than my hand drilled efforts! Bushes and machine screws are a better option anyway, and I've yet to see anyone attempt six bushes with a trem-Leo installation.
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Post by JohnH on Jan 8, 2017 20:31:42 GMT -5
The force in each string is around 7kg, assuming a 10-46 set. If 3 of these go to each end screw, thats 21kg per screw which is about 46 pounds of force.
If someone can suggest the usual shaft diameter and length of screws in a 6-point bridge, I'll look at a structural design standard for timber and see how close this load is to the strength, for either hardwoods or resonable softwood such as Basswood.
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Post by Deleted on Jan 9, 2017 10:01:21 GMT -5
but what if only the first and (say) the third or fourth are making contact? Sooner or later more screws will make contact, due to the wood compressing.
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Post by newey on Jan 9, 2017 21:56:34 GMT -5
If you never use the tremo-Leo, then only two screws are actually contributing, in a static situation. Once you actually use the whammy bar, it's now a dynamic situation, not static, and more than two screws can matter, over time. My 2¢, anyway
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