'myCNC' Journey :p

Hi All,
Long time reader, first time poster.

I have been designing different machines for a couple years now on and off, every time I get half way through I start again with different ideas.
Smaller, Larger, Stiffer, Cheaper.. you get the idea.

My main requirements ( I think) will be:

* Full sheet capacity - typically 2440x1220mm or 2400mmx1200mm.
* Cut and profile Hardwood, HDPE, Aluminium.
* No longer than 3000mm total, No wider than 1500mm. Height unlimited.
* ER32 collet to match my knee mill.
* Prefer low noise.
* Cheap ? ( I know, I know...Aluminium and cheap probably don't sit well together).
* Closed loop steppers.
* Ethernet connectivity.

I'm hoping this thread will become a diary of my progress as I go.
Looking forward to any critique positive or otherwise, suggestions, reality checks.
Attaching my current design which measures 3000mm by 1200mm (Footprint).
I realise I can drop the height a fair bit, I will probably do so whilst implementing some stiffening, also will probably shorten the whole thing to meet sheet size. Need to finalise some other aspects and measure the travel achievable.

Some of the aspects I'd like some comments on include:
* Gear Rack, which size would be suitable, Is mod2 too small?
* Stepper sizing, thinking dual Nema34 12Nm for long axis with rack and pinion, dual Nema23 ~2Nm for the short axis using ballscrew and single Nema 34 12Nm for Z Axis also with ballscrew.
* Overall design, stiffness, vibration, accuracy, parallelism..
* Am I mad?
* Links to similar machines.
* Capability estimation based on known details.

It's still early days, but I have full CAD and FEA software access if required to test various concepts.

Thanks in advance for your comments.

Cheers.

Mick.