New to CNC's 4-axis help

[nat45928]

Hi,

Im brand new to CNC so take it easy on me. :-)

Im looking to make a 3 or 4 axis CNC to cut wax/plastic (to make jewelry molds) wood and possibly aluminum. Something similar to this: micRo-kit. im not sure exactly what i would need to make this a 4 axis cutter. Im also not sure about what software is needed. I have atuoCAD educational versions which i think will work but past there was not sure on what i would need or use. i was hoping to run this on a 64-bit machine so mach3 would be out because it dos not have 64-bit support. And i was also looking at LinuxCNC.org - Home for a CAM program will that work?

Any help and guidance would be appreciated.

Nat

[Harpye]

its not a must but my suggestion...

For jewelery molds you would need rather fine resolution but also small dimension on the axis - no play on the thread nut combination and prett good precision -.. I at least would go for IT 5 Ball threads ( 23micron per 30mm length) with preload on the nut so you can physically avoid the reverse play .

thread height and diameter should give you the possibility to semi step increment the movement to physically 0.01mm.

the 4th axis should be supported with a self locking transmission without play
and a also very fine resoution ... perhaps you could google for "Harmonic Drive"... a metal flex transmission could also work but supports no full turn on the A Axis..

Regarding Cam ... a four axis simultaneous CAM wold be rather high effort
renting a license may come up to several thousand bucks a year....

for working wax you would probably need pressure air for cooling and a rather small and light high speed spindle ....- for larger aluminum parts you would need a larger and more powerful spindle... and all the structure would have to also be stronger ... Dont know, if both materialsin one target would raise the costs of the router.... ( one material is to be worked very precisely and the other one is harder to work with and rather rigid)


Hansjoerg

[nat45928]

OK, so your saying: i need a small table for the jewelry for the high precision. Or go for a larger one and not get good Jewelry results?

[Harpye]

or get both and pay a lot of money for a fast and precise large 4 axis machine

[nat45928]

ok, so what do you think the cost range would be for:

small jewelry cnc
general larger cnc
both of the above

[awerby]

Or to build a machine? It's doubtful that you will be able to build a high-precision wax carving machine better than a professional company which makes that their business and has been doing it for many years. You might build a machine that costs less, but you might spend as much money (or more) and end up with something that doesn't work too well. It's great fun, and certainly a learning experience, but if you're really focused on making jewelry models, then purchasing a CNC machine that's ready to run would probably make more sense than launching into a build project.

The Taig CNC micromill, for example, lists for under $3k new, and it's $700 extra to add a 4th axis. It comes with Mach3 to run the machine. Lots of jewelers use it for highly detailed work in wax and metals. DeskProto 5.0 CAM software, which writes 4-axis code from your designs, would be $1295. So for about $5k, you'd be in business.

Before investing in that Microbot kit, I'd advise you to see if you can find anyone who's added a 4th axis to it, done jewelry on it, and is happy with the way it came out. It looks like it uses unsupported rails, small NEMA 17 motors, and drags its "monolithic" gantry over the base plate, which saves money on slides, but seems to lack constraint. It's difficult to see how a design like this would hold the .001" tolerances they talk about in a finished part.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[Harpye]

For a 200x200x100 working range estimation

I'd also say 6k for the parts costs for the wax machine witout software
I'd also say 6k for the parts costs for the Alu Machine without software

8k to 10 kfor a combination of both functionalities

BUt you could also google for machines to make dental inlays or fitting pieces
like this one ( the WAX application)

Impression-Baureihe | Fräsmaschinen für Dentaltechnik und Mikrobearbeitung | vhf camfacture AG
At least the Jaeger Spindle in this set charges about 2..3 K

but < 5000$ bucks for a supported product, I dont know any machine at least the KMP pcb Mill is about 18000$ and that machine ins not the technical benchmark!

[nat45928]

alright, so what if we dropped the aluminum and just said be able to cut wood foam and wax, and lets go with a smaller design say 24"x24"x12" (X Y Z) so these are my requirements:

1. Cut: Wood, Foam, Wax
2. Size of 12" (X) 12" (Y) 4" (Z)
3. 4-axis cutter

Thanks for the help guys!

[Harpye]

Smaller design..... 12 "


in case of the bigger concept I suggested Smaller range means 100x100x40 mm

= 4"x4"x1,3" working range and this would be precise

What you want is not dental or jewelry but mid size ....

you have to imagine there is a hirarchy on the axis which provides a progressive function on the costs

X axis stand alone alone ....compared with the others .. cheap
+y axis means x axis has to be orthogonally ( y) free of play
so the structure has to be reinforced against bending under tension in y
plus the additional costs for the axis itself
+z axis means x axis has to be orthogonally ( y and z) free of play
so the structure has to be reinforced against bending under tension in y and z
plus the additional costs for the axis itself + machine structure for assembly
of axis
-A Axis will have to be enlarged so the full z axis is able to rotate within the working range so lenth of z Axis has to be doubled what finally means
a totally different machine structure and stiffness and you need special fittings to handle the material in a stiff and non bending way as you will
have to handle it without a solid base - free standing in the working space .. to work with a Z axis in the full range and to cut simultaneos 4 Axis
your working area should rather be dimensioned like a cube or at least same dimensions in y an z as the rotation axis is around the x direction.

BTW - you know that Shapeways also supports sintered metal parts... which would not be manufacturabel by routing process... take a look

Bracelet V by bulatov on Shapeways

If you would like to talk a bit .... you could reach me on skype ... "therealoptimist"...

[nat45928]

OK, so i think i finally understand what your getting at. And i see what you mean by the axis and how each has to be more precise than the next. So what would you recommended as a good machine and software for the footprint you mentioned?

[Harpye]

I'm neither a dealer nor a jewels maker I built a simple 3 Axis machine with a fairly good precision and setup my estimation on the data I gathered

What is the biggest piece you want to go for ???

for rings 4"x4"x4" could be good for bracelets and bigger peices you should have a bigger system but probably would do them in 3 Axis milling process in respect of the instability of the long distances and the instable wax object....

you should write down a spec about the cost affecting parameters which are

Amount o. Axis

Precision

Size of working area

Speed

Material to work with

Depending on this spec you could go for a mill which satifies your needs

You probably will find a very small amount of products which are 4Axis in that size

but from commercial view buying an expensive product is someway cheaper than to spend the effort in developing a own system - especially if it would be your first attempt