Professional 3D artist - machining virgin - what should I buy/build?

[stwagstaff]

Hi,
Apologies for the long post, but I'm brimming with questions.
I've seen lots of postings here that have just served to befuddle and perplex me. I'm looking for recommendations for a specific system, kit, or plans for a DIY kit. The trouble is, I haven't come across anyone making stuff similar to what I have in mind, so I don't feel like I have good direction.

I have worked as a professional 3D artist in the games and entertainment industries for many years (I use tools like FormZ, Rhino and Maya -- see www.wagstaff.info) and I'm fascinated with the prospect of producing some of my 3D designs as physical objects. I also have some ideas for small-scale production -- mom-n-pop-shop objects to produce and sell on ebay, etc. I have an intuitive sense of how 3- and 4-axis mills move from all of my modeling experience, but no idea what their physical capabilities are in terms of cutting different types of materials. The manufacturers seem to all claim omnipotence, so I tend to distrust everything they say.

I have looked at TAIG, MAXNC, and Sherline, Roland and more expensive variations of what appear to be similar turnkey mills, but they have recieved very mixed reviews. On the other hand, I can't handle anything much bigger than 400 lbs -- don't have the space or degree of committment required -- and I don't actually know if bigger machines have the precision, RPMs or finesse to do my mostly very-small-scale projects. I'm game to cobble together a system from readily available parts, but my objective is using the machine, rather than blissing out on building it, and I would probably prefer either a turnkey system or to work with a kit someone else has engineered. (I should add that my budget's somwhere around $3,000). If I do purchase a kit and a machine, like an X3, can I add a 4th-axis table and expect it to work?

Here are some specific things I'd like to be able to do:
4-axis cutting of wax, nylon or aluminum objects up to 5 inches cubed with alternately very smoothly curved finishes (see attachment) or highly detailed bas reliefs (not undercut).
Infrequent, but precise cutting of 2D hole patterns on sheets of 4 x 16 x 1/8" aluminum (mounting/face plates for 3D render servers).
Frequent 3-axis cutting of hemispheres, half-cubes, and other simple shapes -- requiring very smooth finishes - in blocks of graphite (up to 10 x 8 x 5 inches).
Precise, high-quality engraving of jewelry patterns in wax and silver (rings, findings, etc. -- the last two are for my wife, who is a glass artist)

Some specific questions:

For these types of small/light work, how big is big enough?
What's the right range of motor RPMs for this mix of materials?
Is there a compelling reason to shell out $$$ for servos, rather than steppers?
How many oz/in is enough when talking motors?
There's a confusing mess of controllers out there. How do I make sense of them? What works for my needs?
What software do you recommend? (I've already got a modeling pipline -- I need to find software that will efficiently convert my solid or surface models to the required machine code for me).

Thank you thank you thank you for any help!
Sean

[Brian Kidd]

Now by no means do I want to discourage you from purchasing your own CNC machine, I know I would want to cut my own art work out if I could. With that said though, have you looked into having your work created with rapidprototyping? There are several materials availiable in a veriety of different processes to create objects. Here at work I am the RP engineer that creates CAD models (using Unigraphics) to run on our Stereolithography machines. Depending on size and what you want the piece for it might be a good way to go. The one thing though it can get a bit costly (again depending on size) but if it is something you can sell or make dups off from it might be worth that. Other than that I personally don't have a recommendation for any CNC that will do what you want for the price. I am putting together a Industrial Hobbies CNC mill together right now and I would also eventually like to get into 4 axis machining but I have a bit of a learning curve yet to tackle with just learning how to machine in 3 axis. Hope this helps some.

B.Kidd

[Neil_J]

FWIW, I bought the Sherline 2000-CNC, a Sherline lathe, a complete tooling set, servomotors, and controllers for less than $2000, but I wouldn't recommend it for anything other than light to medium work. They're very easy to damage if they're not handled with care. I have, however, used mine for production for a few months (I've had several quality problems on Sherline's end, all of which have been resolved.. Sherline's customer service is good). Accuracy on my machine is excellent. I've engraved titanium rings and other jewelry on mine with great results.

I've heard great things about the Taig, they seem very well-built. The Asian mills are heavier duty, but require a lot of cleaning up and retrofitting to get any kind of repeatability. I wouldn't buy one thinking you could use it any time soon I haven't heard much on the MaxNC, but the CL15 looks like a great deal for the money, if you can live with stepper motors (I personally despise them)... Being a complete kit, you wouldn't have to worry about picking out controllers.

For a fourth axis, some options are to retrofit an asian rotary table (from Grizzly or Enco ), or buy the Sherline 4" table, which should be OK for what you are doing.

Infrequent, but precise cutting of 2D hole patterns on sheets of 4 x 16 x 1/8" aluminum (mounting/face plates for 3D render servers).

16" is pretty big for a benchtop, unless you machine the left and right sides seperately... Another option would be to get the 14" extended X-axis kit for the sherline, I make aluminum panels on mine, you can see pictures of them on another post in the Benchtop section of this forum.

For these types of small/light work, how big is big enough?

I've never met a machinist that wanted a smaller mill. Buy what you can afford, you'll appreciate it later.

What's the right range of motor RPMs for this mix of materials?

A stock spindle on any mill should handle aluminum, but you'll need 10K RPM + for engraving. Again, Sherline sells a 10k RPM kit, which I own, it works great. Otherwise you might have to mount a small rotary tool to your spindle which can be a pain.

Is there a compelling reason to shell out $$$ for servos, rather than steppers?

If you have the money now, buy them If you come up with the money later, buy them. Once you own a stepper setup for a while you'll know why. You never "need" them, but once you use them, you'll never go back. My servomotors go 5-10x faster than my steppers, with a lot more torque. Also, missing steps in the middle of a job is no fun.

How many oz/in is enough when talking motors?

150-200 MIN for steppers, buy the strongest you can afford. My servos, by comparison, are 500 oz.in, and are powerful enough to break stuff.

There's a confusing mess of controllers out there. How do I make sense of them? What works for my needs?

I would get the Geckodrives if you have the knowledge to wire everything up. I haven't seen a complete system for cheap yet, that was worth buying.

What software do you recommend? (I've already got a modeling pipline -- I need to find software that will efficiently

For the CNC control program, I highly recommend Mach3, I wouldn't use anything else. For a CAM program, try out a few of the art-type programs, I couldn't recommend any though.