[Rezort]

Originally posted this in the Australian/New Zealand club house.

Gday all,
I have been reading these forums for over a year now and have recently decided to stop dicking around and build my own cnc machine.

My aims:
300x300x50 work area (12"x12"x5")
Moving table design
As accurate as possible (without blowing my budget out of the water)
Able to mill wood aacrylic and thin alumnium sheets (1-3mm 0.039"-0.118")

My current plans are built around:
60x30mm alu extrusion from Profilium - Aluminium profile | Aluminium extrusion | Framing Systems | Machine Guards (half the price of other retailers I could find).
12mm aluminium plate for the z carriage and spindle mount plate.
20mm fully supported linear rail for all 3 axis. link.
SBR20UU 20mm slotted linear bearings. link.
16 X 4 Acme Trapezoidal Screw. link.
Nema 23 Stepper Motor. link.
400w Chinese Spindle. link.

Now some questions..
Are the nema 23's suitable for this project?
I also found some Nema 23's with dual shaft link, what is the difference and is it worth the extra 20 buks per unit?
Is that little 400w spindle going to cut it? short of buying a 1-2 kw spindle should i perhaps be looking at mounting a hand router? (to do thin alu)
With such a short z axis (50mm movement) is there a better option over the stepper and screw (linear actuator)?
Can anyone recommend a decent stepper controller (prefer 4 axis for future mods)?
I am having trouble envisioning my z axis set up, Im guessing (unlike my linked plans) I need double the clearance (100mm) required under the gantry bottom support to achieve my 50mm workable z axis to allow the spindle plate not to interfear with the movement.
Lastly looking at my sketchup screen grab is there anything that needs changing/is not going to work? (not all gantry brackets drawn in).

I know thats a fair few questions but I would love some advice on my plans.

- Chris

[ger21]

For something that small, those motors should be fine. But, you'd probably be better off with these for about the same price.
269 Oz-in NEMA 23 Stepper Motor (Dual Shaft) [SM-02] - AU$45.00 : Homann Designs!, The preferred CNC Component Supplier

It's not the cheapest, but the Gecko G540 is hands down the best bang for the buck 4 axis drive you can get.
Gecko G540 Stepper Drive REV-8 [G540] - AU$285.00 : Homann Designs!, The preferred CNC Component Supplier

[Rezort]

Thanks for the links Gerry, after reading about the headaches with the chinese controllers I think i will have to lash out on the gecko driver.

Just an update aswell:
Having trolled the internet for hours today at work I have decided to downgrade to 12x3 Acme Trapezoidal Screw simply because I can not for the life of me find a supplier for 16x4 anti backlash nuts.
I am also considering downgrading the linear rails to 16mm.

Seems the last things i really need to figure out is the final mechanical design and which router / spindle to look at.