[kitcabsource]

Hi all,
I have had the bug for sometime.
I need help in getting started.
What I would like to end up doing is 3d scanning live peoples heads( a bust) and machining a duplicate in wood or light weight plaster. Another avenue would be to machine in HD foam then dip the model in a clay like liquid resin to end up with a sculpted looking copy. I also am intrigued with making art and signs from plasma cutting.
I first thought to build a mini Cnc so I may practice using the software and learn all I need to know to set up.
Money is tight so I don't want to waste it on mistakes. I am confused by all the different motors, steppers, screw drives vs chain, 3 axis vs 4,5and even 6 to 7 axis.
I am very mechanically capable, I just am overwhelmed with information. One thing I want the most is for cutting speed to be as fast as possible, some videos I see show very slow movements . Is the nature of the beast or can the right equipment and software cure this, and if so what specs should I look for.
Any suggestions would be appreciated.

[awerby]

That's a pretty ambitious agenda. How much do you have to spend on it? Are you planning on making miniature busts, life size, or heroic size? Have you experimented with this "clay like liquid resin" or just heard about it somewhere? How high a priority is the plasma cutting? Have you got the 3D scanning down already, or do you need to budget for that as well? It's pretty meaningless to start suggesting equipment if it's way out of your price range, but this stuff can be expensive, and the more capabilities you add - plasma, extra axes, more speed - the higher it gets.

Andrew Werby
www.computersculpture.com

[bmellis]

Hi,

I'm relatively new to CNC as well and there is a lot to consider ... I found that anything over 4 axis is just too expensive to get the software / hardware for.
My background while having some mechanical knowledge is stronger on the electrical / computer side of things.

My advice is to pick a modest goal to get started with - e.g. sign work / 2/2.5d work in timber (mdf / ply ... maybe plastic and aluminium) - and see if you can justify the cost.

With regards to cutting speed - this is a function of material "hardness" and $$$s.
The harder the material, the higher the cost to machine it at the same speed.
The larger the motor, the faster it can cut a given material - however a larger motor costs more.

There are some software optimisations around machining (and tool path generation) that will save time; however I'd suggest that are secondary to having a well built and appropriately spec'd machine first.

Other alternatives may be to get your 3d scanning setup going and outsource the making of the items, or consider a 3d printer.

Hopefully this helps.

[ger21]

The first thing you need to do is start reading through the pertinent forums here. Then read some more. And more still. Don't stop for at least 6 months. By then you should have a better idea of what's involved.
You can also start downloading trial software and practicing with it. You don't need a CNC machine to learn how to use one. YOu can use control software like Mach3 to simulate the actual running of the machine to learn how everything works before you get a machine. This will make the process go much smoother once you actually have a machine.

As for your intentions, you're really looking at 3 different machines.

1) A laser scanner. Commercial units start at a few thousand dollars. The cheapest route is probably the David laser scanner. Be aware that the learning curve to get very good results appears to ve rather steep. You'll also need to fabricate some hardware to move the laser and scanning hardware. To do a 360 degree scan of a head, I'd imagine that you'd need to fabricate a system to move the laser and scanner around the head and/or body.

You'll see a lot of posts from beginners who want to be able to click a button or two and achieve perfect duplicate parts or objects. The reality is that technology has a long way to go. Knowledge learned through practice is about the only way to get there with out spending thousands of dollars on cutting edge equipment.

You may also want to look into scanning with an XBox Kinect. Resolution tends to be rather low, but there are a few very inexpensive options out there right now. Again, there'll be a fairly sttep learning curve with lots of trial and error involved.

2) A 4 axis router. More specifically, a 3 axis router with a rotary 4th axis. This should be able to do what you want for the least amount of money. A 5 axis can do things a 4 axis can't, but the cost of the machine and software goes upi exponentially when you get to 5 axis. In the 10 years this forum has been around, I've probably seen less than 5 homebuilt functioning 5 axis machines. They're not cheap nor easy to build.

3) If you want to do plasma cutting, you really should be thinking about a dedicated plasma machine. While I've seen a few combination plasma/ routers, therequirements of the processes are very different and much better suited to different designs of machine. Trying to do double duty adds considerably to the cost and complexity, and the end result is a machine that does neither operationas well as a dedicated machine can do. Expect to spend at least $3K - $4K on an entry level plasma machine, due to the cost of the torch and associated electronics.


As fas as speed goes, it's really quite simple. Speed costs money. The faster you want to go, the more it's going to cost. As speed increases, everything starts to cost more. Better linear bearings to handle higher forces, better motion components to provide efficient high speed motion.

The proper way to choose components, is to design your machine with specific perfomance goals in mind. It's impossible to recommend components without knowing the exact design and construction of the machine, the method used to provide motion, and the velocity and acceleration rates required.