Does anyone know what percentage Aluminium was in the zinc alloy castings?

Brek

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In the 50’s bridges? As I have a friend who loves sand casting and all things manly (seriously, only guy I know who made his own suit of armour for re-enactments), and he would be prepared to cast a few for me. But looking at what was used in the 50’s there are three different amounts of aluminium, I am going to take a wild guess at they used the cheapest lol, which might be the lowest aluminium content.
 

jimi55lp

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I think that's a fair guess since Gibson didn't make bridged, stoptails, wraptails in house but contracted their production.
 

skydog

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If you're referring to ZAMAK (German acronym for zinc, aluminum, magnesium, and copper), I've always heard 4%.
 

Brek

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Thankyou, that’s a number I can start with, even lower than I thought, I had it guessed at 7%. No wonder they collapse on occasion, that’s a soft alloy. But if it’s what gets the tone I’ll copy it.
 

ARandall

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It was usually the other bits....impurities....that seemed to be the issue in the metals made back in the day.
 

Brek

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Any one fancy sending me one for analysis lol.
 

jvin248

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... if it’s what gets the tone I’ll copy it.
That's not where the tone lives .. you'll get there with these mods:

-Pickup height, including screw pole height adjustments
-Pots 'n Caps
-Pickups

While everything 'may contribute' to everything ... you're chasing ghosts after those three areas.
Pots have a 20% tolerance range, caps have a 10% tolerance range, and pickups have some too-wide-to-give tolerance range. Look up Seymour Duncan's website and they will tell you to ignore kohms and just focus on their treble/mid/bass bar charts that have no numerical values shown. Gibson tended to use 300kohm volume pots with humbuckers for that 'darker'/'smooth' tone that for many were 'muddy' and thus the general industry trend toward 500kohm pots. What are you using for pickup trim ring materials? Pickup elevator spring tension? Truss rod?

Melt down the old hot wheels cars and make a new guitar bridge as that will be a cool story to tell. Just don't expect the tone needle to move as much as swapping Pots 'n Caps.

Be sure to check out the zinc toy values before you melt them up ... some of them are worth thousands, due to these kinds of efforts. Skip to 4:30mins to see how mint condition for these cars, in the desired colors, can sell for as much as a new Gibson LP.


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Brek

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I know what you mean, but in this case I am not so sure I agree with what you say about ghosts, the difference from putting a (a bargain price of £40) 1965 abr-1 pat no forge mark bridge on was noticeable on my R0, this was after a previous install of soft brass screws and saddles, and moved another step toward the sound I want, I am after reasonably achievable mods, I am not going to go out and blow a grand on a ‘59 bridge, but if I can get one cast I’ll give it a go. However, the further reading I have done mentions high pressure injection into steel molds quite a lot. I need to do further reading as that maybe for volume manufacturing purposes, I need to find out if low volume sand casting is a usable technique with zamac.

DFE72B0A-EB11-46F7-B8AC-11F1569DE240.jpeg
 

korus

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Alloy: 70% zinc, 30% aluminumn, Google search: Faber 3023 ABRH Bridge

This obviously does not answer your question. But rest assured it was definitely not as high as 30% or 27% (ZA27) or anything above 5%. Alloy used was some Zamak type cause any Zamak is actually softer than ZA27, but we do not know which one. Also when they replaced light Aluminum probably machined stop-bar/tailpiece with heavy 'Zinc' one in early '70s it was also Zamak but again we do not know if it was the same as for body of ABR-1.


Mid '60s. General public starts buying electric guitars. Demand rises 10 or 20 times. And tone changes according to preference of newly discovered market for electric guitars.Tone of solid-body guitars started shifting to suit tonal preference of new customers. So all mods, improvements, cost cuts - call them what you feel like - were all aimed at the same goal - making guitars brighter.

That is why as time passed since mid '60s when changes in alloys first started - both core AND plating - alloys that were used for ALL metal hardware parts on ALL guitars became gradually HARDER, with highest jump in hardness of all commonly available alloys around 1980. Advancement in metallurgy meant harder metal alloys. When you use metal you wanted it harder - durable and oxydation free- for the same cost. EXCEPT for music instruments. You want certain mechanical resonance.

The way choice of material used for guitar parts designs tone of electric solid vody is not a quantum mechanics or the answer to question what consciousness is. It is simple. Harder the part - brighter the tone.

And reversing the equation: higher resonant frequency EQUALS harder alloy. So, you only need to induce mechanical resonance in 2 metal parts and compare frequencies produced - the one ringing higher tone is the harder one.

1.
Drop 2 ABR-1 bodies of different make on hard surface. Drop them on several different hard surfaces. Harder one will produce higher tone. Simple.

2.
Hit them with metal tools of varying mass,

Hit them with metal tool which is MUCH HEAVIER than body of ABR-1 - resonance of the whole body - low frequencies resonance - how it resonates with fundamental and lower harmonics,

Hit them with metal tool which is MUCH LIGHTER than body of ABR-1 - resoance of mostly the surface - high frequencies resonance - how it resonates with higher overtones of string vibration,

You do not want to know amount of time and money I spent on this.

By these tests original nickel plated ABR-1 bodies, before they started chrome plating them, have the lowest resonant frequencies.It seems lowest hardness of a Zinc / Aluminum alloy is Zamak7 with hardness ot 80.

If you can find ANY Zn/Al alloy with lower hardness than this one (80) use that softer one. If you do not find softer, use Zamak7. Simple.

The same goes for saddles and saddle screws. Most likely it was softest brass - which was barely enough Zinc in Copper to be called brass and not just Copper - surely no more than 20% of Zinc, but more likely 15% or even only 10% of Zinc in brass used. Copper that is barely brass. And it was machined not cast, at least saddles, cause they have visible marks even underneath the plating. They have chosen softest variants of ALL alloys they used - carbon steel, brass, Aluminum, Zamak - to pass most of fundamental and lower harmonics through to wood - help wood make final tone less metallic. Carbon steel used was most likely 1010 or 1008. Aluminum was likely also machined meaning not cast, cause again bottom of tailpiece has marks.

Softest you can find. Softer it is, wood performs it's role better - reduce harsh treble-ish metallic sounding ring of metal string on metal hardware, by enabling wood to create more resonance with wood as wood is the softest material - to make tone more mids rich and by that - closer to human voice. Mechanical resonance is tone.That is what makes factory originals made pre mid '60s for musicians (who hear treble above human voice well) with their mids rich tone superior to bright thin sounding post mid '60s guitars made for general public (who hears treble poorly so they need more treble in tone of guitars to hear balanced tone).

Softest alloy for any of the alloy names they used - by composition and by production method. Simple. It means softest Zamak. It is Zamak 7, AFAIK. Only 3.5-4.3% of Aluminum, the rest is nothing but Zinc.

scroll down to the bottom of page
 
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Subterfuge

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I know what you mean, but in this case I am not so sure I agree with what you say about ghosts, the difference from putting a (a bargain price of £40) 1965 abr-1 pat no forge mark bridge on was noticeable on my R0, this was after a previous install of soft brass screws and saddles, and moved another step toward the sound I want, I am after reasonably achievable mods, I am not going to go out and blow a grand on a ‘59 bridge, but if I can get one cast I’ll give it a go. However, the further reading I have done mentions high pressure injection into steel molds quite a lot. I need to do further reading as that maybe for volume manufacturing purposes, I need to find out if low volume sand casting is a usable technique with zamac.

View attachment 505846
sand casting is a very primitive form of casting, it goes back to the time of the Egyptians ... and only gets you into the ballpark as far as any accuracy is concerned, further machining is always needed if accuracy is needed, which it always is .. it think the bridge would definitely be injection-molded ... making a proper die is no small feat .. good luck
 

Brek

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Lol thanks, not going there, unless, i just thought, I can sweet talk the universities engineering dept to take it on as a research project, lets see if I can get one of the students interested, hmmm.
 


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