CNC machining--costs?

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Please FedX me whatever you are smoking this evening!

 

Dude, wtf are you thinking about doing?!

 

expanding a 3D object in a CAD system is not as easy as enlarging a photo in photoshop.

 

I think Uro should be consulted for this one. Uro can refer him to a plastic surgeon or specialist.

 

The "Why the **** are you doing this anyway?" part Is the TVR running yet? Go drive that bieaotch!

You should be able to scale something in just about any decent CAD program. How big will the final result be? That will determine what kind of machine has to cut it, which will be most of your cost (asside from a few $k to scan it.)

 

It's typically not cheap, unless you know someone who can do it. It's not really difficult work, most just charge a lot for it.

 

It would cost a shatload. The problem with doing a car is you would need multiple set-ups on the machine. For example, to carve the top you would want to hit it from the top, but to carve the sides and cut wheel openings you want the car mounted sideways. Figure you would need setups for the top, left, right, front, rear, and perhaps the underside. That's 6 different holders for a one-off part. The better way would be two setups on a 5-axis machine... of course a 5-axis is probably going to cost around $300k or more for the machine and anyone that runs one is going to want - maybe $100/hour+ to have it pay it's way.

Also, machining curves is a biatch. With a mill, it has a theoretical single point of contact with the part. Contouring (cutting curves) is generally done with a ball end mill, and to get things super smooth you generally would go with a .001 stepover. That means the machine cuts the line, then moves over 1/1000th of an inch and cuts the next one. If your part is 6" wide, that's 6,000 passes on that one panel. If your part was, for example 10" long, that's 60,000 inches of movement of the machine to cut that one curve. If it's an easily cut material that you can run through at 300 inches per minute, that's 200 minutes just on that one surface. Of course, that's a finishing pass and you need to do a roughing pass before that to get close to your final curve (final cut must be small to get a good finish).

I can give you an example... you know those small sized handheld phones (non flip) like the nokia? Well, one HALF of the steel mold that makes the case of that takes a while to cut. It's basically a "negative" of the actual phone, cut very smooth. On a Makino high speed machine with a 30k spindle (machine cost - about $300k plus), you're looking at 80-90 hours of cut time, more than 2/3rd spend on finishing/contouring. That's a single setup just to cut from the top.

Of course, doing the CAM work and generating toolpaths would easily take a guy a few days (20-30 hours for an experienced guy). A holder to hold your model in different ways would probably take several hours of design and cutting for each different hold position.

Yeah I can totally see why it would be $10k.

But there are much better options. A better option would be to laser scan it (big bucks but it's the "right" way to get it scanned in), then build it on a rapid prototyping machine. You could have the whole thing done in a day depending on size. Both those machines are boku dinero though so it ain't gonna be cheap!

Hope it helps.

 

This is why resin models are much much cheaper and made in not too much time. But enlarging, that would not be an option. You'd have to redo the cast, create the mold and then throw in the resin to create the object.

If you have the skematics for one in say 1/24th and you want to enlarge it to 1/12, you can do that - and there are some fab companies that specialize in this kind of work down in Mexico or over in China for rapid prototyping.

 

Awesome.


Cost is dependant in large part on SIZE of the object. If we're talking full size car, then the machines that have that kind of travel are big big $. Some are in the single $million figures.

Rapid prototyping a 24" long model based on your 12" model is much easier. But the laser scanner is still probally 150grand, as is the RP machine.

Then there's some resin.

CibaTool SL5170 resin, a common photopolymer used in stereolithography, typically costs about $800/gallon.

Check these guys out: http://www.stratasys.com/NA/index.html

 

I'd have to dig up some old numbers from a few years ago. I mention Mexico because a couple of Texas guys at SEMA had opened up a shop down there, when they lived near the border (Laredo maybe?). Even going through a SEMA directory would give plenty of sources for fabricating, molding, or rapid prototyping one of the items you seek.

Sorry I cannot be of more specific help, it's been a while.

 

Look for a beureu service that has a machine called the Z-corp 3d printer. Its basicly a printer that can produce working 3D objects within hours. Quite amazing acutally, I was being given a demo of it, and it produced a working gearbox (yes with moving gears) straight out of the machine.

Unlike resin prototyping, this machine can make any shape, and structure (like an apple tree with apples hanging), whereas resin rapid protyping is limited by things like parts that overhang and as such.

The good thing about the Zcorp machines is that for a few hundred dollars and a few hours, they can produce a metal investment cast, which you can use to cast your metal casting. The surface is a bit rough, but 8 hours of sanding detail would make it suitable for smooth metal casting.

Ive used this many times at college when creating my 3D models from 3d computer meshes.

hope this helps.