Help and Suggestions Needed for 4' x 4' x 2' Printer

Hiya All,

Apologies in advance if I've inadvertently posted this in the wrong place.

I've been intending for quite awhile to design a very large 3D printer but just recently got the time to work on it. I've got a few parts picked but wanted to run my design and a few questions by the more experienced hobbyists of this forum before I bite the bullet and pay for components.

General Specs I'm set on:

Outer dimensions of the frame: 58 in x 52 in x 21 in
Likely going for a 3mm extruder given the larger scale of the printer (unless anyone can provide a significant reason to opt for 1.75)
No heated bed for cost and size reasons

I have several specific questions I'd like answered but appreciate any sort of input. This is my first attempt to build a 3D printer, though I've used and fixed various issues on multiple printers, so apologies if some of these questions are somewhat rudimentary.

My biggest concern is the control board. Currently I'm looking at Smoothieboard V1.3 with TCM2130 stepper drivers. Smoothieware has a seemingly excellent guide for installing their boards found here: http://smoothieware.org/3d-printer-guide. Are these boards for the most part plug and play? There were also several options for stepper drivers. I'm hoping TCM2130s function for general NEMA17 steppers but am unsure If there are specific drivers I need.

Do I need stronger/faster steppers given the scale of the print area? What spec should I be looking for in steppers? Most generic I could find on Amazon was a pack of 5 NEMA17s marked as 42Ncm Would different steppers require different driver chips? I would assume if I need significantly stronger steppers I would need drivers capable of delivering more power.

How should I go about making the printbed? Sheet metal/plywood with masking tape over it? I assume I will need some mechanism for leveling it. Are there tried and tested methods for making your own leveling system or is it even necessary given the 6 points of contact stabilizing it?

My current plan for a power supply is to get a 12V 20W supply and just get a 5v regulator to power the Smoothieboard. Will a single 20W psu power the steppers and the smoothieboard through the 5v regulator? Does anyone know of a tried and tested PSU for Smoothieboards?

My X and Y axis are directly belt driven while my Z has a belt going to two Ball Screws. Will the rubber of the belts stretch or flex significantly over the course of 4 feet?

I've attached some rudimentary sketches of my design.

Hmm, a 4 foot long belt is going to struggle.
Makes a lot more sense to have a motor each end with much shorter belts.

You're going to need big arse motors anyway.

20watt 12v psu ? Not a chance in hell !

think more along the lines oof 3-500 watt and 24 v.
https://www.amazon.com/LETOUR-96V-24...532295&sr=8-48

Your heated bed - assuming it's heated - will need a mosfet and be directly maind powered anyway. So the psu is just for the motors and electronics.

no matter what you use for a bed, that thing will weight a LOT - it's going to take some really beefed up motors. at least one of these at each side of all your axis would be my minimal starting point: https://www.amazon.com/STEPPERONLINE...9531751&sr=8-6
Assuming the bed moves, from the sketches all I can think is you are building an i3 design with moving bed.
Not how I would go for that size - I'd either make a delta or a fixed bed cube with three axis extruder movement.

The big issue is going to be momentum. The motor not only needs to move the weight of the gantry and printbed - but it has to be able to stop it instantly as well.

board wise think more along the lines of s duet wifi 1.4 clone (or actual duet if you can afford it)
You need something easy to upgrade and add bits to.
The machine is makeable - but you need to drastically uprate your specifications :-)