Set Screws, Cup Point vs. Flat Point

[Cyrus Comiskey]

Hi,

  I'm placing an order with McMaster-Carr for various sizes of set screws to be used mainly in electric guitar bridges and I had a question regarding the point on these screws: Is it better to use flat point or cup point set screws? My first instinct would be that flat points add a little more surface area and would transfer vibration slightly better, but I pulled a few screws out of a few bridges and all were cup point. Am I missing something? Is it a matter of cost? or do cup points make better contact? Thanks!

  Cyrus

[Justin]

My thoughts on this would be to get the cup point and not the flat ones. The reason being is that I would say saddles are not always parallel to the bridge and they will sit at a slight angle when properly adjusted, not always but often. So the cupped ones would work in any situation, where the flats may have less contact with the bridge if the saddles are not parallel to the bridge... If they were flat then just the edge of the screw would be in contact with the bridge.

[Paul Verticchio]

I've used these before.  I perceived better string to string note separation and a bit of a clearer 'ring'. The difference was subtle....very subtle

http://www.mcmaster.com/#18-8-stainless-steel-set-screws/=shc7od

Another option:

http://www.mcmaster.com/#18-8-stainless-steel-set-screws/=shc9n3

The oval base makes 'strings on' adjustments a breeze.

Your mileage may vary.

Cup point set screws utilize the rim of the cup for the bearing surface.  The 2 types I posted do the same with a bit more finesse.

Any discussion of which is better would surely be academic at best. The most important factor is the quality of the saddle itself.

Let us know your results with your chosen type?

Best of luck :)

[RETROROD]

My plus thoughts are toward the 'cup point' set screws. I agree with Paul.

In the world of "audiophile audio" it is theorized that 'isolation' of components is best done with 'points' versus 'flat foot' contact with the surface.

A similar theory related to guitar "may" apply??

[Cyrus Comiskey]

Thanks Guys!

 I think I'm going to order the cup points and oval points! I figure I should try them both out and see what I like.

 Paul, I never even would of thought of the oval points, but now that I look at the info, I'm intrigued! Thanks for the heads up.

 Retrorod, I'm curious about this theory of isolation and plan on looking it up. Is this mainly in regards to, say, the contact points on the bottom of a speaker? Also, as it applies to the guitar, wouldn't we be trying to "couple" rather than isolate? Or am I showing how little I know about the physics of sound?

[RETROROD]

Yep Cyrus, I am most likely thinking about two different theories for two different purposes..yikes!  It is fun to 'ponder' though....

[Russell Vance]

Yep, the points on the isolation feet of the turntables and amplifiers etc are designed to minimise the transmission of sound energy and frequencies both ways - ie; inbound from the vibration of the furniture and equipment bases in response to high SPL's causing resonance and feedback frequencies in the surrounds (including the room) and also to prevent cross coupling between components due to transformer hum, acoustic vibrations  and stuff like that going outbound (although this is probably a little over the top) and being introduced into associated equipment.   Some gear for instance has isolated power sections in separate boxes etc.  

Whereas, our good ole geetar stuff works better when the string energy transfers into the hardware and body components (generally speaking).  

Dome/oval points are probably the best for doing this - but, conversely, as any Tele owner with an old bridge will notice,  the guitar sounds better when the standard issue cup head saddle screws start to bite into the bridge plate and cut their own groove.   Everything starts to sound better and more solid (not to mention the saddle stability and harmonics improving as the saddle anchors to the base plate and stays put under pick attack) along with sustain and drive improving.   So, in the grand scheme of things both styles have  advantages - but I will definitely have a look at the oval head screws which Paul has discovered for us - looks good.  Little things like this, especially in the bridge/saddle area have a way of making useful differences.  Stainless steel screws are also always a good idea in the bridge saddles, so that's another bonus.

Regards, 

Rusty.

[J R Emmett]

I'll offer a different thought - ball (or spherical) tip screws.  These are not widely available but are pretty easy to make from the pointed variety of set screw.  A ball tip that is concentric with the screw centerline will result in a stable, consistent mate to the bridge plate. 

In theory, the cup and flat point configurations should do the same thing but the points are rarely machined true to the screw axis. This results in both inconsistent adjustment motion and lack of consistency of how the saddle sits on the bridge.  In any case - whether the contact is spherical (ball tip) or circular (flat or cup) - you should ideally only have a single point contact with the bridge plate because the saddle will almost always be angled with respect to the plate.

Ball tip fabrication is best done on a lathe but can also be done by gripping the screw in a cordless drill and shaping the point of the screw on a 1" belt sander while the drill is turning.  I also use this technique to shorten bridge screws (a frequent customer comfort request) and bevel the thread ends to facilitate screw insertion. 

[RETROROD]

The theory and explanation sounds "spot on" to me!

Good tip on the drill/beltsander also..Great minds on the Frets.com Forum.....

[Robbie Collins]

Are we talking about set screws to lock the bridge to the post?

If so, and we're talking about an old ABR-type bridge with studs and wheels, my thinking is that most string energy is transferred from the bridge to the wheel to the stud to the body - which is a rather imperfect system for transferring string energy due to the 3 transition points. 

The set screw keeps the bridge from rattling and tightens the bridge to the stud. Now vibrations are being transferred through two paths - (1) from bridge to set screw to stud to body and (2) the original path. I'm thinking that two paths increases the possibility of null points and wave interference though not by much since the length of the paths are only minutely different.

I think that set screws improve transfer by forcing the other side of the stud hole wall against the stud, making the contribution of set screw itself relatively small since the surface area of, say, a flat or cup point is small in comparison to the bearing surface of the wall of the stud hole against the stud.