[macintologist]

Remember when Jobs introduced the TiBooks, he was talking about how great Titanium is, how it's stronger than steel but lighter than aluminum IIRC.

So why did he change his mind after 2 years and go to Aluminum which is aircraft grade (didn't he say that about Ti as well?) and is stronger than steel but very light as well?

All I know is that Ti had to be painted and was therefore easily scratched. Whether it looked better than Al is entirely subjective. What about the strengths and density/mass differences of the two.

[Bryans]

Originally posted by macintologist:
Remember when Jobs introduced the TiBooks, he was talking about how great Titanium is, how it's stronger than steel but lighter than aluminum IIRC.

So why did he change his mind after 2 years and go to Aluminum which is aircraft grade (didn't he say that about Ti as well?) and is stronger than steel but very light as well?

All I know is that Ti had to be painted and was therefore easily scratched. Whether it looked better than Al is entirely subjective. What about the strengths and density/mass differences of the two.

off the top of my head...

-Ti laptop shells are most likely more expensive to produce
-Ti case leads to poor airport reception
-Ti must be painted (with all the well known flaking issues) whereas aluminum can be anodized.

[TampaDeveloper]

One other thing is TI is more brittle even than Aluminum

[Luca Rescigno]

Originally posted by Bryans:
off the top of my head...

-Ti laptop shells are most likely more expensive to produce
-Ti case leads to poor airport reception
-Ti must be painted (with all the well known flaking issues) whereas aluminum can be anodized.

Hit the nail on the head.

I think there's also the heat issue as well. I think aluminum dissipates the heat better. Of course, I think that also means the aluminum will get hotter, right?

Anyway, those three are the main reasons... cost, airport reception, and paint flaking. Maybe they also moved to aluminum because of the introduction of internal bluetooth, and they wanted that to have a good range as well.

[ChrisF]

Originally posted by Bryans:
off the top of my head...

-Ti laptop shells are most likely more expensive to produce
-Ti case leads to poor airport reception
-Ti must be painted (with all the well known flaking issues) whereas aluminum can be anodized.

Any metal case leads to poor wireless reception- it's just that the design of the antennas on the titanium Powerbooks is inferior to those on the Aluminum 'books.
The paint that peels on the Powerbooks is actually on the carbon fiber painted frame, not the titanium itself. Either way, it's really ugly.
Chris

[DeRobeHer]

I believe the Aluminum is also easier to shape. The ALBooks are much more curvy than the TiBooks ever were.

[SEkker]

I think it's also because aluminum CAN be anodized -- so they're set for many different colors in the future.

I think the Al is a much nicer feel to it. too.

[SEkker]

[d_oob]

in other words:

Apple chose to go with form over function. Because Titanium was the cool material of the time and would generate such a buzz when people heard that "oooh that laptop there is made of TITANIUM..." Didn't they even bother to test if it would work and take all the damage and if it would or wouldn't chip. Seems like pretty shooty craftmanship. TiBook probably the worse designed laptop? It looked cool and all but shoot my plastic pismo has better reception (in general) than the ti did. Not to dis Ti users. My friends have those laptops and thought about getting one too. But hmmm... most of those friends have had so many problems with there's.

booo form over function

[d4nth3m4n]

Originally posted by SEkker:
I think it's also because aluminum CAN be anodized -- so they're set for many different colors in the future.

I think the Al is a much nicer feel to it. too.

they have had anodized titanium bike components for almost a decade now. like rainbow titanium spokes.

aluminum is lighter (less dense) than ti, but has issues with shearing so often an amount of it is needed that brings the weight up to that of a titanium fabricated piece.

ti, therefore is heavier, but has more flex to it, and will not shear and crack like alu will.

as far as the alu curves vs. the titan lack thereof goes, i think that is just a statement of the design o the times.

the shift was probably made to improve wireless reception and dave money.

[amazing]

The worst thing about the anodized aluminum is that a lot of people are getting pitting and corrosion on the palm rests.

[mainemanx]

Somebody could make a lota' money selling replacement cases for owners of pitted, dented, warped, hot aluminum PowerBooks.

[slider]

Originally posted by d_oob:
in other words:

Apple chose to go with form over function. Because Titanium was the cool material of the time and would generate such a buzz when people heard that "oooh that laptop there is made of TITANIUM..." Didn't they even bother to test if it would work and take all the damage and if it would or wouldn't chip. Seems like pretty shooty craftmanship. TiBook probably the worse designed laptop? It looked cool and all but shoot my plastic pismo has better reception (in general) than the ti did. Not to dis Ti users. My friends have those laptops and thought about getting one too. But hmmm... most of those friends have had so many problems with there's.

booo form over function

I am guessing that what Apple's goal was was to make the PowerBook 1" thin. Threre are many things one just can't predict about a product until it is produced and actually handle by thousands different people. I think they weighted the pros and con, plus they needed to get a faster chip in there. I remember reading that they had no idea how they were going to get a G4 into a PowerBook, it seems making the case metal was the solution, at least a piece of the solution. I am sure there are trade offs with both materials. Personally I would have been pissed if I saw 'paint' flaking off my machine. I love my 15" Al

[TheIceMan]

Originally posted by d_oob:
...Because Titanium was the cool material of the time and would generate such a buzz when people heard that "oooh that laptop there is made of TITANIUM..."

Agreed. I think the main reason for the switch from titanium to Aluminum is MARKETING. Titanium was the "it" word for a while, so everything was supposedly made of titanium. Then that word got old, so in order to sell more laptops, Apple came up with some other "catch word." Look how many bought into it. Had "Aluminum" came out first and "Titanium" to follow, the exact same thing would happen now. People would come up with ways to say how much better Titanium is better than Aluminum. It's marketing, pure and simple, in my humble opinion.

[Fyre4ce]

Originally posted by macintologist:
Remember when Jobs introduced the TiBooks, he was talking about how great Titanium is, how it's stronger than steel but lighter than aluminum IIRC.

So why did he change his mind after 2 years and go to Aluminum which is aircraft grade (didn't he say that about Ti as well?) and is stronger than steel but very light as well?

All I know is that Ti had to be painted and was therefore easily scratched. Whether it looked better than Al is entirely subjective. What about the strengths and density/mass differences of the two.

I am a mechanical engineer and I use titanium, aluminum, and steel extensively. Mini-materials lecture to follow. Read if interested. It's a bit of an overkill response, but I know there are some inquiring minds out there which will find this interesting.

Terms of interest to us:

Stress - load per unit cross-sectional area, or the "intensity" of a load. If a 1/2" x 1/2" square rod of some material is being pulled on length-wise with a tension force of 10,000 pounds, the stress is 10,000 pounds / (1/2")^2 = 40,000 psi. If the same 10,000 pound load were put through a 1/4" square rod, the stress would then be 160,000 psi. Stress has the same units as pressure, usually either pounds per square inch (psi) or newtons per square millimeter (MPa). Sometimes you'll see "ksi" which just means 1000 psi. Also notice that the length of the rod does not affect the stress in the material, when the rod is loaded in the manner I described.

Elastic deformation - the change in shape of a material, caused by the application of a load, such that the material will return to its original shape. Think of a rubber band - you pull on it, it stretches. You relax - it returns to its original shape. Every material will exhibit elastic deformation for some range of stress. Steel deforms elastically, just like rubber. The only difference is that the forces are much much higher and the streching is much much less.

Plastic deformation - the change in shape of a material, caused by the application of a load, such that the material will NOT return to its original shape. Think of play dough - you pull on it, it deforms, but it does NOT spring back like rubber. Plastic deformation is almost always a BAD thing for the part. This is because the part is changing shape, but more importantly because the part is absorbing energy, and there's only a certain amount of energy it can absorb before it breaks.

Yield Strength - how much stress a material can take before it starts to deform plastically. Since plastic deformation is BAD, the yield strength is usually the strength engineers design parts to not exceed.

Hardness - resistance to physical penetration. There are "hardness-testing" machines that drive a cone or ball into the piece being tested with a very precisely-controlled amount of force. The deeper the dent made, the softer the material is. Hard materials are resistant to wear and scratching, etc. Interestingly, there is a very strong correlation between hardness and strength. This means that you can take some piece of steel of unknown origin, put it in a hardness tester, and based on the hardness, look up the strength in a table. This is preferable to loading the piece to failure in a tension testing machine.

Ductility - the ability to deform plastically without breaking. Copper and play dough are both ductile materials, because they can be bent/drawn out/beaten into different shapes without breaking.

Brittleness - the opposite of ductility. Concrete and granite are both brittle materials because they cannot deform plastically - they just break. Brittle parts will fail catostrophically.

Steel: Steel is a mixture of iron (an elemental metal) and carbon (a non-metallic element). Relative to other structural metals, steel is pretty heavy, with a density of about 7.9 grams/cc. Normally (in "normaized" condition), steel has a strength of 40,000 psi to 60,000 psi, depending on what other elements are added to it. A big advantage of steel is that it can be "heat-treated" to greatly increase its strength (and hardness). The practical limit is somewhere around 300,000 psi, and this strength is possible only for a small number of steel types. When heat-treated like that, the steel becomes very brittle and also becomes "notch-sensitive," meaning that a very slight surface scratch will cause a crack to propogate and will reduce the part's effective strength by a huge amount. That's why hardened steels are generally used only in controlled applications like internal engine parts, or when the hardness is required, like for a chisel. Steel is relatively cheap to produce and is a very abundant material. It's also cheap to manufacture, because it can be formed into whatever shape is necessary while it's soft, and then it can be heat-treated up to whatever strength is required. However, it's being replaced by titanium and aluminum for many things because of its high density.

Aluminum: In its elemental form, aluminum is very weak, and has about the strength of wood. However, it can be alloyed with silicon and precipitation-hardened to 40,000 psi to 70,000 psi while still maintaining reasonable ductilty. The best property of aluminum is its low density: 2.7 grams/cc, about 1/3 that of steel. It's relatively easy (and cheap) to manufacture. It also has a very high thermal conductivity - it carries heat well.

Titanium: As is the case with aluminum, pure elemental titanium is pretty soft and weak. However, when mixed with about 6% aluminum and 4% vanadium, the yield strength shoots up about 160,000 psi (and the hardness increases greatly as well). Addition of other metals can get the strength as high as 220,000 psi. These alloys are very expensive to make, and since it does not heat-treat like steel, you have to form/cut/machine it in its hardest form. This usually requires special, expensive tools, making the manufacture of titanium parts an extremely costly operation. For some applications, though (airplanes, space ships, race cars, etc.), it's well worth the cost. Structural-grade titanium alloys have strengths higher than all but the hardest steels, have great ductility, and have a low density of 4.5 grams/cc. The strength-to-weight ratio of titanium is one of the highest of any material. Titanium also has an extremely poor thermal conductivity, which can be good or bad depending on the application.

The titanium used on the old PowerBooks was not structural grade. It was so-called "CP99" meaning "commercially pure 99%." It is neither hard nor strong (strength = ~35,000 psi), and seems to me an odd choice of materials. Its very low thermal conductivity makes it a poor choice for laptop material because it effectively insulates the internals and keeps the heat in. Structural-grade titanium would have been a better choice but it would have added at least $100 to the cost of each PowerBook, and it would still have had the heat conduction issues.

Aluminum seems a much better choice. It is ligher, and the aluminum used is probably precipitation-hardened, making it harder and stronger than CP99 titanium. And it's also a great conductor of heat, making the whole body of the computer a giant heat sink.

Damn, that was long, but I hope you all learned something. BTW, I'm typing this from an aluminum PowerBook!

[Fyre4ce]

Originally posted by TampaDeveloper:
One other thing is TI is more brittle even than Aluminum

This is not true. 6-4 titanium has an elongation @ break of 10% and CP99 is 30%. Aerospace-grade aluminum is about 12%.

[Fyre4ce]

Originally posted by Luca Rescigno:
Hit the nail on the head.

I think there's also the heat issue as well. I think aluminum dissipates the heat better. Of course, I think that also means the aluminum will get hotter, right?

You're absolutely right that aluminum dissipates ("conducts") heat better than titanium. This keeps the temperatures COOLER, though. Think about it - you've basically got the whole area of the laptop available for giving off heat into the surrounding air, so even a small temperature difference between the aluminum skin and the surrounding air will give off large amounts of heat. Since titanium conducts heat poorly, only a portion of the titanium will be hot while the rest will be cool. The part that's hot, though, needs to be REALLY hot because its surface area is so small. The aluminum spreads the heat around to get rid of any hot spots in the machine, and it also sucks it out better to the surface of the machine, so it can be carried away by air.

[Link]

The only negative thing about using aluminum over titanium is that it's VERY flexible in comparison to titanium or any other metal, and in a laptop where thickness is a concern, this does not mean a good thing..

The fact if you drop a powerbook from 1' off the ground, less than if it fell off a table and that it'd get dented noticably scares me.

Especially because my previous laptops have had a few falls like that before. The aluminum is just TOO delicate.

[yoesh]

thanks for the great primer on materials science, Fyre4ce!
it was a good read and reminded me of some weekend "lectures" that my grandfather would provide when i would visit...

[flypenfly]

Who cares about the hot spots, I care if my lap gets too hot using a laptop. If the TI can keep the heat away from me, all the better. I don't need third degree burns on my legs.

[iomatic]

Read fryre4ce's post a little more thoroughly?

Originally posted by flypenfly:
Who cares about the hot spots, I care if my lap gets too hot using a laptop. If the TI can keep the heat away from me, all the better. I don't need third degree burns on my legs.

[tooki]

Originally posted by Bryans:

-Ti case leads to poor airport reception
-Ti must be painted (with all the well known flaking issues) whereas aluminum can be anodized.

The reason the TiBooks had bad AirPort reception was because the antennas were inside the bottom half of the unit. Having the antennas INSIDE a metal case was a harebrained idea. The AlBooks not only give the antennas proper plastic openings, but also put them on the screen.

The same effect would have been achieved by moving the antennas on a titanium machine.


Titanium most certainly can be anodized -- you can get anodized body jewelry and bike accessories readily. Titanium can't be anodized to true black, though -- aluminum and niobium can. (Niobium is another metal used for body jewelry, but it's extremely heavy and thus unlikely to be a suitable candidate for a laptop.)

Fyre4ce: awesome post!

tooki

[masugu]

Based on all the commentary...and the need to distinguish the new G5 PB...I am betting on either some new flavor of black plastic or aluminum / plastic combo. Cannot do white since iBooks own that space...but maybe in black plastic with AL...I dunno

[flypenfly]

"Read fryre4ce's post a little more thoroughly?"

Except I did. From actual prolonged usage, AL laptops definitely do get hotter at 1ghz all around. Personally I prefer the TiBook looks but as far as heat dissapation goes, I believe the Tibook has a better layout including superior battery life, reliable screens, and basically the same performance at 1ghz. The two things AL books got going is the superior AP reception although late model TiBooks have noticably improved eception and the backlit keyboards. Also, the 1.25ghz speed is only availabe in AL although without the L3 cache the TiBooks have. The DDR advantrage is negated by the lack of L3 cache.

I wish they made a TI edition of the 1.25 ghz AL books but heat might have been a factor.

The heat inside the Tibook is insulated far more than the AL until it reach a plateau and its still within safe operating temperature of the components inside so really, I don't mind if its internally hotter inside the Tibook, it doesn't make me feel uncomfortable.

[Link]

On second thought, I think apple just used aluminum this time around knowing it would reduce the lifetime of the powerbooks significantly, meaning sooner repeat buyers..

Mark my word. After seeing recent "OMG I dropped my laptop 10 inches and it got dented badly!" posts, I have absolutely no trust in that design.

[Fyre4ce]

Originally posted by flypenfly:
Who cares about the hot spots, I care if my lap gets too hot using a laptop. If the TI can keep the heat away from me, all the better. I don't need third degree burns on my legs.

Originally posted by flypenfly:
Who cares about the hot spots, I care if my lap gets too hot using a laptop. If the TI can keep the heat away from me, all the better. I don't need third degree burns on my legs.

It doesn't quite work like that. All else equal, the average surface temperature of the laptop MUST be at least a certain value if all the heat the computer's making is going to be dissipated. (This is a fair assumption. For brief periods of time, heat can accumulate inside the computer, as when the computer is first started up, but the laptop must reach thermal equilibrium eventually or the internal temperature would approach infinity). The material that forms the laptop's skin doesn't really affect this minimum average temperature - it's a function of only the power drawn by the computer, the ambient temperature, the surface area, and the heat transfer coefficient (which depends on air speed, among other things). So, an aluminum powerbook's skin will heat up quickly and reach thermal equilibrium, while the titanium powerbook is still cold. It's still cold because the titanium insulates the internals, and the internals need to get very hot before the heat can get out through the insulating titanium.

In summary: the titanium holds the heat in, and will cause the internals to get much hotter than a similar aluminum powerbook. The skin if the aluminum will get warm faster when it's turned on, but will keep the internals cooler by quickly conducting heat out to the surface where it can be carried away by ambient air.

If you want your legs to stay cool, you have basically two choices:

(1) reduce the power draw of the internals of the machine. This will reduce the surface temperature required to dissipate that power and will make a cooler laptop

(2) insulate the bottom of the computer with titanium or a similarly poor heat conducter, while making the sides and top out of aluminum. The heat needs to get out no matter what, but doing what I just described will carry it up and away from your legs, and out into the air. This is a fair design, but it effectlvely cuts the available area for heat dissipation in half.

Make sense?

[Fyre4ce]

Originally posted by flypenfly:
"Read fryre4ce's post a little more thoroughly?"

Except I did. From actual prolonged usage, AL laptops definitely do get hotter at 1ghz all around. Personally I prefer the TiBook looks but as far as heat dissapation goes, I believe the Tibook has a better layout including superior battery life, reliable screens, and basically the same performance at 1ghz. The two things AL books got going is the superior AP reception although late model TiBooks have noticably improved eception and the backlit keyboards. Also, the 1.25ghz speed is only availabe in AL although without the L3 cache the TiBooks have. The DDR advantrage is negated by the lack of L3 cache.

I wish they made a TI edition of the 1.25 ghz AL books but heat might have been a factor.

The heat inside the Tibook is insulated far more than the AL until it reach a plateau and its still within safe operating temperature of the components inside so really, I don't mind if its internally hotter inside the Tibook, it doesn't make me feel uncomfortable.

The "equilibrium" temperature (the maximum temperature the computer reaches once it's completely warmed up) depends only on:

-the power consumed (dissipated) by the internal components
-the surface area of the laptop available for heat transfer
-the ambient air temperature
-the convection coefficient (related to air speed, etc.)

An aluminum computer will not reach a higher skin temperature - it will just reach the equilibrium temperature more quickly. After it's turned on, the titanium computer's skin will stay cool for a while - because all the heat is staying in the internals and getting them very hot. It's only after a while that the titanium's skin will heat up. The titanium requires a very large temperature difference across it to get the heat out - meaning that the internal temperature is higher than with aluminum, and the skin temperature is exactly the same. If you think the aluminum was hotter over the whole surface, it's because of some reason other than the aluminum. See above.

EDIT: Additional comment. I looked up the thermal conductivities of grade 1 titanium and aerospace-grade aluminum. The thermal conductivity of the titanium is less than one tenth that of the aluminum! This means that, all else equal, the temperature of the internals will be more than 10 times hotter relative to ambient temperature than it would be with aluminum. That's pretty hot.

[flypenfly]

"An aluminum computer will not reach a higher skin temperature - it will just reach the equilibrium temperature more quickly. After it's turned on, the titanium computer's skin will stay cool for a while - because all the heat is staying in the internals and getting them very hot. It's only after a while that the titanium's skin will heat up. The titanium requires a very large temperature difference across it to get the heat out - meaning that the internal temperature is higher than with aluminum, and the skin temperature is exactly the same. If you think the aluminum was hotter over the whole surface, it's because of some reason other than the aluminum. See above.

EDIT: Additional comment. I looked up the thermal conductivities of grade 1 titanium and aerospace-grade aluminum. The thermal conductivity of the titanium is less than one tenth that of the aluminum! This means that, all else equal, the temperature of the internals will be more than 10 times hotter relative to ambient temperature than it would be with aluminum. That's pretty hot."


Yet its still well within the design specifications for the system so it doesn't really affect anything. Operating temperatures inside the Tibook can't be so hot as to destroy the internals. In fact G4-400 Tibooks are still running fine today although I imagine they dissipated less heat. In either case, the higher clocked Tibooks from real world experience still seem to eminate much less heat, although I haven't used it on my lap for more than an hour and a half and not doing full core work.

The biggest draw back I see to the Ti over the AL in terms of thermal properties is that the Ti would force the fan on more frequently but there seems to more air ducts (3) although I don't have an AL here to compare directly right now.

Yet it seems a small price to pay when you consider the much shorter battery life, inferior screens, fit and finish issues, bendability, and other quality issues that have plagued the AL 15inch series of powerbooks.

Now as far as material concerns govern, how does plastic fair in thermal transfer? I ask because of the Dells I use, they do get uncomfortably hot.

Also, I think I saw a form of magnesium as a case material for either a PDA or digital camera, is it feasible to make a laptop out of that?

[Link]

food for thought: poorer heat dissipation == colder surface.

That means your tibook won't become your crotch warmer nearly as fast as an albook

Granted that, they need better cooling designs.. but the aluminum is fine.. DEFINATELY needs a better frame to withstand drops/dents/dings and whatnot tho

[ngrundy]

Originally posted by tooki:
The reason the TiBooks had bad AirPort reception was because the antennas were inside the bottom half of the unit. Having the antennas INSIDE a metal case was a harebrained idea. The AlBooks not only give the antennas proper plastic openings, but also put them on the screen.

A couple of others have mentioned it but I'll also note the following. A bit of basic radio theory says that you automaticly get around 10db loss in signel when you cross polarity. 99% of the access points you buy have the rubber ducky antenna in a vertical position, giving a vertically polarised signel. the Ti's antennas run horizontally. db is an exponential scale, 3db is a doubling of power. I personally have my AP setup with it's antenna laying horizontaly to give the best coverage possable in the house. also being a diversity unit i can run the other in vertical to get the best of both worlds.

And of course having the radiators stuck in your lap when you're trying to access a network device doesn't help, Especially at 2.4ghz, a freq that water loves to absorb.

[runejoha]

I thik the answer is simple. Costs. Al is cheaper, and the competition is harder. F.eks the Compaq Armada was more robust than the Evo nootbooks today. Look at the Dell PCs which are very cost effective. Pure plastic. (ouch! - I really wonder why a customer wants to spend $2000 on that crap)

runejoha

[d4nth3m4n]

Originally posted by Link:
food for thought: poorer heat dissipation == colder surface.

That means your tibook won't become your crotch warmer nearly as fast as an albook

Granted that, they need better cooling designs.. but the aluminum is fine.. DEFINATELY needs a better frame to withstand drops/dents/dings and whatnot tho

but once the tibook is hot, it will stay hot longer than the al book as the albook will already have lost the heat.

[Dr.Michael]

Hello Fyre4ce ,

thanks for your very informed comments.

Can you please answer one more question that might be interesting for aluminium owners?

Alu tends to corrode very fast and thus gets covered with a white oxide. My alu Powerbook already shows slight beginnings, especially at the palmrests and on the top where I touched it.

How can we prevent oxidation or remove the oxide and how should we treat the alu to clean it?

Some people - maybe with agressive sweat - already report that they have wholes in the case. So a good an regularly applied cleaning method seems to be important.

Is the anodized aluminium less sensitive against acids and oxygen than the normal aluminium?

Michael

[Fyre4ce]

Originally posted by Dr.Michael:
Hello Fyre4ce ,

thanks for your very informed comments.

Can you please answer one more question that might be interesting for aluminium owners?

Alu tends to corrode very fast and thus gets covered with a white oxide. My alu Powerbook already shows slight beginnings, especially at the palmrests and on the top where I touched it.

How can we prevent oxidation or remove the oxide and how should we treat the alu to clean it?

Some people - maybe with agressive sweat - already report that they have wholes in the case. So a good an regularly applied cleaning method seems to be important.

Is the anodized aluminium less sensitive against acids and oxygen than the normal aluminium?

Michael

You are right that aluminum is more prone to corrosion than most metals, and you're also right that anodizing aluminuim does help somewhat. There is another anodizing process called "hard anodizing" that's normally used to protect aluminum from corrosion. If you were really ambitious, you could probably take out the aluminum palm rest and pay to have it hard-amodized.

Hard anodizing is one of many coating processs that are designed to protect from corrosion. There is also powder coating, and I'm sure there are other processes that I've never heard of. Of course, a simple paint might also do the job. In short: there are many options.

[tooki]

Originally posted by flypenfly:
"Read fryre4ce's post a little more thoroughly?"
The two things AL books got going is the superior AP reception although late model TiBooks have noticably improved eception and the backlit keyboards.

NO TiBook's reception is comparable to that of an iBook, Pismo, or Aluminum G4.

There absolutely were not any TiBooks with backlit keyboards, that was introduced with the 17" AlBook.

tooki

[timster]

Also, I think I saw a form of magnesium as a case material for either a PDA or digital camera, is it feasible to make a laptop out of that?

The earlier Apple PowerBooks (Duos, and possibly Pismos) had magnesium frames.

I'm no metal expert, but based on what I've learned from the bike industry, magnesium is crazy light and strong, but it's also very brittle. Might have been an factor in the design decisions.

Plus imagine what would happen if your magnesium powerbook happened to catch fire???

[pete]

I'm just curious. The IBM thinkpads, in my opinion, are the most durable of all laptops. They seem almost indestructable - especially given how people seem to abuse them. No powerbook can compete in my experience. Some of them use a magesium composite - does anybody know anything about that?

[timster]

oh yeah, the current iBooks have magnesium frames too.

[Kleejam]

Perhaps LiquidMetal (metallic glass) will be the next step in powerbook frames/shells.

quote:
- approximately 2.5 times the strength of commonly used titanium alloy and 1.5 times the hardness of commonly used stainless steel
- Excellent durability
- Scratch and corrosion resistant
- Non-reactive

see:
http://www.liquidmetal.com/applications/dsp.casings.asp
http://www.liquidmetal.com/technology/default.asp

[flypenfly]

"NO TiBook's reception is comparable to that of an iBook, Pismo, or Aluminum G4.

There absolutely were not any TiBooks with backlit keyboards, that was introduced with the 17" AlBook.

tooki"


Sorry it was my poor wording, I meant the AP reception is improved in late model TiBooks compared to early models. Also I didnt mean the TiBooks had keyboard illumination, I meant the illum is something the AlBooks have that is an advantage over TiBooks.

[Paul Huang]

Because titanium is easier to shape, Apple is able to turn it into a sharp angle. If it is not as easy to shape, it would have more curves. Don't forget that thickness is another factor.

Originally posted by DeRobeHer:
I believe the Aluminum is also easier to shape. The ALBooks are much more curvy than the TiBooks ever were.

[riverfreak]

Wasn't the aluminum powerbook released just to conceal the anemic upgrade to the internals?

[milhouse]

Originally posted by Fyre4ce:
I am a mechanical engineer and I use titanium, aluminum, and steel extensively. Mini-materials lecture to follow. Read if interested. It's a bit of an overkill response, but I know there are some inquiring minds out there which will find this interesting.

...
Damn, that was long, but I hope you all learned something. BTW, I'm typing this from an aluminum PowerBook!

Sweet Post!!

I was just trying to "sort out" the different material properties the other day.

Much simpler if you actually know something about material science...

thanks again

[milhouse]

Originally posted by Dr.Michael:
Hello Fyre4ce ,

thanks for your very informed comments.

Can you please answer one more question that might be interesting for aluminium owners?

Alu tends to corrode very fast and thus gets covered with a white oxide. My alu Powerbook already shows slight beginnings, especially at the palmrests and on the top where I touched it.

How can we prevent oxidation or remove the oxide and how should we treat the alu to clean it?

Some people - maybe with agressive sweat - already report that they have wholes in the case. So a good an regularly applied cleaning method seems to be important.

Is the anodized aluminium less sensitive against acids and oxygen than the normal aluminium?

Michael

It's actually the layer of oxidized material that will prevent additional corrosion, ironically.

[tooki]

Originally posted by Paul Huang:
Because titanium is easier to shape, Apple is able to turn it into a sharp angle. If it is not as easy to shape, it would have more curves. Don't forget that thickness is another factor.

Uhhh, Ti is a LOT harder to shape than Al.

read Fyr4ce's post, wouldja?

tooki

[inigopete]

I've been watching this thread as I've just been given a TiBook (minus half it's internals) and am debating either building it up or selling off the bits. It's been dinged in a couple of places and it's surprisingly tough to bend back into shape.

My question is: does anyone know how difficult / expensive it would be to get a whole new case (or pair of case halves) made from stronger grade (or thicker) titanium? I have no connections with machiners or CNC people but it appears to me there's a bit of a niche.

: P

[jasonsRX7]

Originally posted by pete:
I'm just curious. The IBM thinkpads, in my opinion, are the most durable of all laptops. They seem almost indestructable - especially given how people seem to abuse them. No powerbook can compete in my experience. Some of them use a magesium composite - does anybody know anything about that?

I'll second that. I just switched from a Thinkpad T40 to a 15" AL Powerbook. Although I love being able to run OS X on the road, I really miss the ruggedness of the Thinkpad. I carry the Pbook so gently and pick it up like it's made of glass, and I'm always scared of denting it. But I could literally toss the T40 on my bed or couch and not think twice about it. I would 10 times rather have a plastic/composite Powerbook than a dentable metal one. I've owned a total of 5 Thinkpads, and a couple of them have been cracked, but a thin fracture is nowhere near as bad cosmetically as a huge dent.