[PsyKotyk]

This might be old news to you guys, but I was completely blown away.

Worth the repost if even one person hasn't seen it.

http://www.kirkhammotorsports.com/book_aoe/

[mactec54]

Hi Psykotyk

Yes they are very cool

[Geof]

The topic was thrashed to death on Practical Machinist; some of the machinists were not impressed by a 'billet' aluminum car.

[ihavenofish]

The topic was thrashed to death on Practical Machinist; some of the machinists were not impressed by a 'billet' aluminum car.

the way i look at it is - the bicycle industry used to make everything from billet in the late 80's, early 90's, and as every part ended up breaking, these days everything is forged. virtually nothing billet on a bike anymore.

so if aircraft grade 7075 billet isnt strong enough for a little human, its probably not ideal for a car.

that asside, im most impressed by the body work. shiny! (and illegal to drive in canada).

[ViperTX]

Well, it appears from the FEA that they covered most everything they had to. I wonder if the car has any miles on it.

I'm not sure why the PM guys would trash this project...jealousy....or maybe just pm syndrome....*chuckle*

It's a work of engineering art at the very least.

Paul

[ihavenofish]

It's a work of engineering art at the very least.

from the "just cause we can" standpoint, its great. only thing that would have made it better is an original body design i think.

i browse PM occasionally, and i always get the sensation that anything thats not a model train isnt very welcome there.

[Geof]

...jealousy....or maybe just pm syndrome....*chuckle*.....Paul

Now I wonder what pm syndrome is; *Chuckle*

That car is a tour de force of engineering and machining. I am not a car fanatic so to me it seems a bit pointless but then I guess some of the things I am interested in seem pointless to a car fanatic so we are equal.

[bsdphk]

The topic was thrashed to death on Practical Machinist; some of the machinists were not impressed by a 'billet' aluminum car.

They are likely missing the point, having never driven a car of that class themselves: Getting 300% more stiffness and a sizeable reduction in mass, at the same time, makes a whole lot of difference.

Poul-Henning

[peter.blais]

Those guys are local to me. I don't think it makes much sense to machine EVERYTHING just because... Each part should be evaluated for the proper manufacturing technique, be it casting, stamping, machining, etc.

That said, they are really low volume, and the tooling cost of many of the other options is probably the REAL driving force behind that decision.

Those guys hired a bunch of russian sheetmetal guys who used to build MIG's to do the sheetmetal. What you see there really is what you get, aluminum so perfect it can be polished and displayed without filler or paint.

As for why... well, you just have to be a car nut, otherwise it makes no sense. I'm one, but I still wouldn't buy that, i'm not into the "replica" scene. There are some LSx powered mid engine supercar "kits" i wouldn't mind constructing though.

[Geof]

I had not looked at their book until now and I found this quote that is attributed to Voltaire:

"No problem can stand the assault of sustained thinking."

I think this project showed the quotation is incomplete and this should be added:

...If enough money is thrown at it.

[bsdphk]

Those guys are local to me. I don't think it makes much sense[...]

You should read some the chapters of the book they offer for download, what they do make perfect sense.

The point being missed here: They were not trying to build a good looking car or a reasonably priced car.

They were trying to see how little metal you need to build a race car, and they removed what they didn't need using CNC tools, because that was the best way to do it.

The metalurgical argument is that as soon as you get Alu above various "magic" temperature(s) (ie: by welding it) you loose strength, and dimensional stability, which means you have to use more metal to get the same strength.

Check out in the pictures, how they leave plenty of material where the bolts/dovels are, but in areas where only in-plane strength is necessary, they leave only a fraction of an inch in thickness.

If you did that and welded it together, you would have to anneal the entire chassis afterwards, and God knows what shape it would be then.

To say they are low volume is not even close: they built a prototype and the delivery issue.

The car was ordered by Larry Ellison, the $ALOT fella behind the Oracle Database company, who, I gather, is somewhat into cars :-)

And yes, the polish guys doing the platework is awesome.

And I personally dig how they decidede to let the CNC process define the surface texture, even though more orthodox CNC'ers find that "leaving traces like that" is "unprofessional".

Now, what we need you to do, is to pop around, and get a copy of their G-code for us...

Poul-Henning

[Geof]

....The point being missed here: They were not trying to build a good looking car or a reasonably priced car.

They were trying to see how little metal you need to build a race car, and they removed what they didn't need using CNC tools, because that was the best way to do it.

The metalurgical argument is that as soon as you get Alu above various "magic" temperature(s) (ie: by welding it) you loose strength, and dimensional stability, which means you have to use more metal to get the same strength....

Poul-Henning

Good point; in that respect my comment about it being pointless is rendered somewhat invalid because pursuing an exercise like this could have useful spinoffs for very lightweight manufacturing techniques.

[ihavenofish]

my friend is drooling over this one:

welded sheet stainless steel gt40 chassis.

i always liked this one:

lotus elise extruded and bonded chassis. if i did a chassis, it would probably be in this fashion. (particularly with access to some of the best extruding tech here in toronto).

the billet car - other than for show - doesnt make alot of practical sense. there are many ways to build a better stronger stiffer and lighter chassis as other industries have gone through the motions already - in fact so has the auto industry.

the height of cnc bicycle millery in the early 90's:

and the beginning of the realization they were on the wrong track.

[saltytri]

As an owner of one of the Kirkham family's "ordinary" cars, I can tell you that their work is simply awe-inspiring and they are good guys to boot. Granted, the whole Cobra thing is an acquired taste but it becomes easier to understand when you get to drive around the countryside in a mirror-polished aluminum car that looks great, is unreasonably powerful, and makes a whole lot of noise when the go pedal goes down.

It's worth going over to PM to read David Kirkham's comments on the car and the process. Maybe he'll show up here, too. David....?

Actually, it was ownership of the car and some visits to the shop that piqued my interest in machining. You ought to see the stuff they've got. Talk about tool envy. And now I've gotten seduced into CNC as a result! I should send David a bill for what it's cost me.

[saltytri]

Good point; in that respect my comment about it being pointless is rendered somewhat invalid because pursuing an exercise like this could have useful spinoffs for very lightweight manufacturing techniques.

Asute observation. These guys are continually refining their product and it is highly probable that things they learned in the process of doing Larry's car have found their way into the "ordinary" cars.

[Geof]

.....It's worth going over to PM to read David Kirkham's comments on the car and the process. Maybe he'll show up here, too. David....?

Do you really think it is worth wading through all the other 'comments'; my preferred word also begins with 'c' but I try to be polite.

Actually it would be worth it because he did put the correct perspective on the project.

[John Crawford]

There's a long thread on the car at www.clubcobra.com under the Kirkham forum. Anyone who has an interest in automobiles and is near Provo, UT would probably enjoy a visit to their shop. I walked in off the street about 5 years ago and Dave and Tom Kirkham were very gracious. Dave showed me their operation and I chatted with Tom about engineering a bit. Nice folks.

[High Seas]

YIPPIE -- Yet, another AC Ace/Cobra look-alike.
Mind You -- Nice approach using the tools, machining, engineering, and approach.
Yet why not do something original?
Obviously there must be/is a customer base -- even if it is only one!

Just my .02

[Geof]

.....Yet why not do something original?...

Just my .02

Look at the age of the buyer. He has the money so he doesn't have to make do with a PT Cruiser or remade VW Beetle to feel nostalgic.