Ah, good to see another South African on the forum. I'm very much in the same boat as you trying to figure out what's the right direction for my build. There's much more knowledgeable people on here than me so I'll leave the comments on your design to them.


Apart from the great build threads here's some of the stuff I found extremely helpfull with a design


To calculate critical speed on ballskrews and motor sizing a great help is also. Can't find the link now but If search on here you'll find it
MotorCalcs.zip


Extremely usefull to compare stiffness of different design options.
cnc_stiffness_calculator_v8 (look at post #26)
http://www.mycncuk.com/threads/7733-...r-design/page3
Or you can just spend endless time fidling with FEA software and be none the wiser :-)


A few general comments:
Helped a friend of mine build a router and he got those Wantai steppers and motors from MicroRobotics and he's very happy with them.


Not sure what your requirements are wrt the 4th axis but be realistic in your expectations. I have a UniCam router with a 4th axis and I have not used that functionality in the 5 years I have the machine. Maybe it has changed recently but in my experience I have not found any reasonably priced software that can do true 4th axis toolpathing. Sure, if you want to engrave text around a cylinder there's plenty free stuff around that will wrap a 2d path around a cylinder.


The stuff from CNCDirect are top notch. Piles of wood dust made on my router over the years and the SKF bearings are still smooth as silk. You may also consider the Hiwin rails. I ordered Hiwin rails from Wendy's Bearing Store http://www.aliexpress.com/store/637430 Payed on the Wednesday and they were in my hands the next friday so I'm very happy with her service and the rails seems to be of very good quality and probably comparable to the SKF suff. The chinese ballskrews and nuts is not comparable to the SKF producs but considering the price I think they are great value for money. I decided to give them a go so we'll see how that works out.


Good luck with your build and if you find other useful local suppliers for the bits and pieces please let me know, I'll do the same.