What Is "cast Metal"

[iskim86]

i've been hearing this term lately when it comes to guitar bridges. can someone expain to me what the differences between die-cast metal and metal are? and how they apply into the construction of guitars

thanks

[M_A_T_T]

I'm pretty sure 'die-cast' is molten metal poured into a mold, and 'metal' is milled from a block.

[egdeltar]

Cast metal is an object that has been made by pouring molten metals into a mold. Machined metal is a form that is cut out of a solid peace.

Ill explain a little further, I used to work in a foundry.

First the master is made; this is the exact shape of what the product is supposed to look like. It is either carved out of solid steal or plastic and are called “tools”. These hollow forms are then filled with wax, these forms are then dipped into slurry and various sands. The sandy wax mold is then put into a large auto-clave and all the wax is melted out.

Next the molds go through a huge oven where they are brought up to temperature; from there they are quickly taken out of the oven, sat in a cart and filled with molten metal. From there they go to knock out where the shell is broke off with basically a huge squirt gun. Then the trees are cut off the molds. Next comes various stages of finishing including sanding, tolerance and clearance test, x-ray tests and slew of other rigorous tests.

There are a few others forms of this process but they are all basically the same basic idea.

As for machining, the metal starts as a block form, attained from a foundry where it was poured into this shape. The blocks are put into various machines like CNC, mills, lathes, stampers, formers to achieve the design...etc. etc... Hope that all makes sense.

Edited June 6, 2005 by egdeltar

[jay5]

Is my understanding that typically machined parts are better than cast parts? Or is it all realitively the same at the end of the day?

[Maiden69]

Machined and Forged are always better than casted.

[iskim86]

Machined and Forged are always better than casted.

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how so?

[Devon Headen]

Cast metal is an object that has been made by pouring molten metals into a mold. Machined metal is a form that is cut out of a solid peace.

Ill explain a little further, I used to work in a foundry.

First the master is made; this is the exact shape of what the product is supposed to look like. It is either carved out of solid steal or plastic and are called “tools”. These hollow forms are then filled with wax, these forms are then dipped into slurry and various sands. The sandy wax mold is then put into a large auto-clave and all the wax is melted out.

Next the molds go through a huge oven where they are brought up to temperature; from there they are quickly taken out of the oven, sat in a cart and filled with molten metal. From there they go to knock out where the shell is broke off with basically a huge squirt gun. Then the trees are cut off the molds. Next comes various stages of finishing including sanding, tolerance and clearance test, x-ray tests and slew of other rigorous tests.

There are a few others forms of this process but they are all basically the same basic idea.

As for machining, the metal starts as a block form, attained from a foundry where it was poured into this shape. The blocks are put into various machines like CNC, mills, lathes, stampers, formers to achieve the design...etc. etc... Hope that all makes sense.

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That's lost wax casting, but he asked about die casting. Just do a google search and I'm sure you'll come up with good info, I don't feel like typing up info that's already out there . Forged parts are usually better because the cast parts tend to be more brittle. The act of forging compacts and toughens the structure of the steel. That's not to say there's anything wrong with cast guitar hardware.

[M_A_T_T]

Machined and Forged are always better than casted.

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how so?

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Don't really know, but would it be a strenght thing? Cast are cheaper to produce, I believe, that's why they are generally cheap to buy, not to mention they usually use cheaper materials when casting.

[westhemann]

cast metal has alot more impurities in it...making it more brittle

[thedoctor]

Naw, it's simpler than that. Die-cast is a metal mold that is pressure-filled with molten aluminum, zinc or "pot-metal", a blend. Cast is where a high-temp mold is prepared for gravity or pressure-fed alum., steel or other alloy. Forged is where a mold is made that can handle the pressure of hot-stamping an alloy by compression to a denser version of the original alloy. Forgings rule but they are expensive to make the compression molds for. Die-cast is a very cheap, fast way to make a lot of parts in an alloy that lends itself to lower-temp casting; zinc, tin, alum. Die-cast can make a very accurate part at high production rates but the material is always of the softer variety. Forgings are used for higher-strength alloys but almost always require post-machining. Real cast iron is done with the sand-mold made from a copy of the part made of foam or wax or steel that is removed before the "pour" is done. If you want a simple, though not completly accurate, test of die-cast or forged/cast, put a magnet to it. Die-cast is not magnetic as no steel(ferrites) are involved. Oh, crap! How many IMHOs do I have to put in now?

Edited June 6, 2005 by thedoctor

[Sparky]

Machined and Forged are always better than casted.

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how so?

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Not true. As usual, it all depends on what "better" means. Does it mean a stronger part? Does it mean a cheaper part? Does it mean a more dimensionally accurate part?

Die-casting is a specific form of casting. It uses high pressure to litterally inject the molten metal into a mold. Without going into great detail, it costs a great deal of money to set up initially, but it can make parts very quickly (easily several parts per minute) and efficiently. There are limits as to what kind of material (you can only die cast the lighter metals, such as aluminum and magnesium) and how large a part can be. The surface finish is very good and you can get pretty good dimensional accuracy. This means you wont have to do any machining to the part afterward before you sell it, so it costs less to make. If I recall, matchbox cars are die-cast. Small, good surface and tolerances, and cheap.

Forging invloves taking a hot part (in this case, "hot" means the part is above 0.5*melting temperature, not hot to the touch) and uses forms to pound/hammer/press the part into shape at incredibly high pressure. Think of your old-timer blacksmith hitting a hot piece of metal with a hammer. But now think of him being 1000 times stronger and with a hammer in the shape of the part he wants. If you do the forging right, you can orient the grains in the metal in the direction of the most stress the part will endure. This means you will have a much stronger part than a machined part of the same shape (the machined part will have randomly oriented grain structure). There are many types of forging, just like casting, but that is the extreme basics.

Machining is your basic metal cutting...somehow, metal is removed from a part to get the right shape. You can get the best tolerances and very good surface finish from machining...but it costs a ton if you are doing a large run of parts and as said before, will not give you added strength or toughness. You can always heat treat the material afterwards to gain more toughness and strength, but that costs a lot to do as well.

The process described above is a type of casting called "lost wax casting" GM has recently begun using a similar process to use die casting on entire engine blocks...this is crazy because in the past, it was very hard to get a part that large and complex made through die casting (there are issues with entrapped air in the die and portions of the melt solidifying before the entire part is cast)...they use a foam that is melted out instead of wax...fun stuff.

Casting is fun...I made an ash tray (dont even smoke) using a sand casting technique.

As for a guitar bridge, in general, a machined bridge will cost more and *could* be more dimensionally accurate. But a die cast part is probably just as good assuming the same material/design...and it will be cheaper to make. I can see no distinct advantages in one proccess that can't be achieved in the other as far as a guitar bridge is concerned. The aluminum bridges are die cast, certain steel parts on a trem bridge will probably be forged and/or heat treated.

[Maiden69]

Well, go ahead and have your cast metal. I will have it machined anyday before casted.

Casting is a lot cheaper than any other method, but for strenght and durability, machined or forged is 100 times stronger. If not why will racers spend the extra money on Forged pistons, cranks, rods. The casted ones are half the price... sh... get an engine an put it thru more the 7 pounds of boost with casted pieces and you wiull have to pick up the pistons on the track.

As for a guitar bridge, in general, a machined bridge will cost more and *could* be more dimensionally accurate. But a die cast part is probably just as good assuming the same material/design...and it will be cheaper to make. I can see no distinct advantages in one proccess that can't be achieved in the other as far as a guitar bridge is concerned. The aluminum bridges are die cast, certain steel parts on a trem bridge will probably be forged and/or heat treated.

HAve you ever seen a machine or forged bridge block crumble like a cookie? I bet not. I had 2, not 1, but 2 die cast standard tremolo blocks crumble on me, and I don't abuse it as much as Wes might.

And tell me which aluminum bridges are casted, so I won't buy them, I hope you aint talking about tail pieces, because they are forged, (at least the good ones), One prime example is Driskill guitars, here a nice link for you and other to learn a bit about why machined could BE better.

Well enough of a rant, if you want to get a casted piece, go ahead and get one, If it is my choice, I would get a better one, you pay for what you get.

[westhemann]

HAve you ever seen a machine or forged bridge block crumble like a cookie? I bet not. I had 2, not 1, but 2 die cast standard tremolo blocks crumble on me, and I don't abuse it as much as Wes might.

main thing i have had is a problem with stripping of the blocks holding the string clamp.(the threads that the screw threads into) on cheaper trems...

that doesn't happen on original floyds...i assume because it is all hardened steel,rather than cast...

but i have to tighten those clamps down pretty good or else the string will slip out over a duration of heavy abuse.the only way i can keep my trems in tune during extreme use is by tightening the dogsh** out of everything.

[jmrentis]

Just thought I'd jump in here to ask a relative question. What about brass bridges, I've read a lot of different opinions on this site, some say they are a terrible tone metal, and some say they are the best. Are they as good as steel parts? Are they ever die casted or are they machined and hardened. I would like to buy myself a hardtail bridge, the ones I seem to like the best are brass, and seem to be more expensive compared to regular die cast bridges. Thanks for your input. Jason

[Sparky]

Easy maiden, I meant no disrespect in my post. I simply disagreed with your assesment that forged or machined parts are "better" than casts parts. It's all relative.

I am not sure why you are under the impression that a machined part will be stronger than a cast part all else equal. If you used the exact same materials and a decent casting process you can get them to be about the same given the same geometry.

As I already pointed out, casting has limitations in the type of material, so you may be comparing machined parts that are made from stronger materials in the first place. E.g. your forged tremolo is steel and you can't use steel in die casting, so you are comparing a steel part to an aluminum part with roughly 1/3 the tensile strength of steel and even worse when it comes to wear and fatigue.

I agree that forged parts are stronger. As I already stated, forged parts are much stronger than cast because the microstructure of the metal is altered. This is why rolled screws are stronger or "better" than machined screws.

In my last paragraph I guess I should have specified for "non-trem" bridges, I dont see much benefit to a forged part over a cast part for a simple non-trem bridge. So I can see your frustration when I generalized to all bridges. If I were designing a trem, I would be using a good steel - so die casting is out the door.

[iskim86]

thanks guys. the reason i'm asking is because i believe the tune-o-matic bridge on my ESP LTD is die-cast and really cheap, because the saddles are wearing out from palm-muting. i thought it was unbelievable for metal to just wear out and have the edges round out over time. are all tune-o-matic bridges die-cast?

and i'm guessing tremolos would be better when it's machined. actually wouldn't it only if the knife edges and the studs were machined out of steel?

[westhemann]

are all tune-o-matic bridges die-cast?

no...the saddles on good toms are hardened steel.

check out tone pros bridges...best toms money can buy

[iskim86]

are all tune-o-matic bridges die-cast?

no...the saddles on good toms are hardened steel.

check out tone pros bridges...best toms money can buy

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the $16 gotohs from warmoth should be equally as good right? considering the fact that gotoh makes tonepros brides.....

[Maiden69]

Just thought I'd jump in here to ask a relative question.  What about brass bridges, I've read a lot of different opinions on this site, some say they are a terrible tone metal, and some say they are the best.  Jason

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Follow the link that I posted above.

http://www.driskillguitars.com/tremolo.htm

Sparky, no disrespect taken, I was under the impression that you wasn't aware of the actual difference. But you sum it up here.

As I already pointed out, casting has limitations in the type of material, so you may be comparing machined parts that are made from stronger materials in the first place

This is the main reason why the other 2 are better. Most casted materials, atleast the ones used in guitar bridges are are made of a mix of aluminum-zinc and/or copper, not the strongest of materials. Aluminum on the other hand is a very good one, but if used alone it shrinks and therefore needs to be macined to its final shape (and this is not cost effective, since it will defit the cost reducing casting method).

Most aluminum bridges out are either forged, or machined. I haven't used one but it is the latest rage in SM, and quite pricey compared to the metal counterparts.

What was the topic again?...

[westhemann]

are all tune-o-matic bridges die-cast?

no...the saddles on good toms are hardened steel.

check out tone pros bridges...best toms money can buy

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the $16 gotohs from warmoth should be equally as good right? considering the fact that gotoh makes tonepros brides.....

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they are not the same.just because the same people commission them does not mean they make them to the same specs.i have a gotoh bridge and a tone pros bridge.they look similar,but the tone pros is heavier(better material)and goes into heavier inserts made of better metal.why do you think they are $70 more in cost?certainly not just the litlle allen screws holding the bridge and tailpiece on the post?

faulty logic by far

[Jester700]

Another note on trem bridges... One of the best Floyd copies is cast - the Ibanez Edge series. It gets away with this because the stressed parts like the knife edges and the intonation screw holes use hardened steel inserts.

[jmrentis]

Driskillguitars

Thanks Maiden69, that website was very informative. I really liked all the products that they make, just some of the best looking stuff out there. I think now that brass seems the best way to go for me. If I wanted to, I could always put in some hardened steel saddles, even though this won't change the bulk of the metal, I think it would change the sound a little because that is where the strings rest on. Anyways thanks again for the link, helped out a lot. Jason

[thedoctor]

Except for the high-pressure points of your trem pivot, brass is a VERY durable metal and will wear with all but the hardest of steels when rubbing on strings. The difference between cast brass and machined bar stock brass is almost nil. The plating will be gone in a hurry, however.