Hi Ron. Welcome to the Zone!
Here's the link for Promica:
Firstly, I definitely like the way they have mounted the motors. This is the way I would design a kit. However, I see serious deficiencies in the way they have implemented it.
1. Motors: 270 oz is too small to properly drive the X3 axes. They compensate by gearing down the motor, but that just really limits rapid speeds to a ridiculous level. WOW! 1500 mm per minute? thats just 59 IPM--Very slow.
2. The Z will be WOEFULLY underpowered with the 270. The X3 Z needs at LEAST a 640 oz N34. You will probably be able to watch paint dry faster than your Z will move up and down.
3. This kit seems to be very expensive.
At the very least, cancel your motor order and see if they will supply a N34 Z mount and 1:1 pulleys/belts for X/Y. Maybe they can also supply the N34 1.23:1 1/2 inch bore pulley/belt for Z.
This is the electronics I would recommend.
$289 G540 This IS a deluxe, advanced features breakout board also.
$098 Keling KL23H2100-35-4B 381 oz motors for X and Y
$099 Keling KL34H295-43-8A 906 oz N34 motor for Z (Detunes to 520 oz W/G540. Changing Z pulley to 1.23:1 = 640 Oz)
$060 Keling KL-350-48 48V/7.3A PSU. (This will handle 3 motors. 4th axis may need more amps.)
$014 pulley https://sdp-si.com/eStore/PartDetail...52&GroupID=217
This will give upwards of 150 IPM on all axes.