Planning out a CNC Router build and was wondering what is going to give me the best performance...having a single stepper driving the gantry from one side or having two steppers driving the gantry from both sides, is two as easy as one, i am assuming a master slave relationship between the steppers would have to be established. I will be using linear shafts with bearing blocks for the motion on this axis
Any help you guys can provide such as articles perhaps previous threads would be great
It really depends on the size of the machine you are building and the size of motors and drives you want to use.
If your machine is medium small and/or you invest in bigger motors and a bigger drive for that axis (e.g. you do NOT get one of those stupid, ultra cheap, Chinese, TB6560, multi-axis drivers where each axis must then get the same power, and one mistake can fry all your axis) then you can run a fat single motor drive system quite nicely for the gantry and lighter/smaller drive systems for the other axis.
If you have a larger machine, or you want to run multiple smaller motors / drives then using two is perhaps worth the extra hassle. The only real issue with two is the extra cost of lead screw and nut, bearings, or other drive hardware but that generally isn't terribly costly, and then you must make sure the two motors and their drivers never skip a step and so get cocked out of alignment with each other. They will tend to re-align while running, but obviously, that isn't what you want happening... The extra motor vs one larger motor may or may not be an issue cost wise.
Start with what you want to build and use this calculator to figure out how much drive power you will need for that gantry moving axis:
If your needs seem extreme, then move to two drives and so divide that drive requirement by two.
You can look into what motors might handle the load as well... Sometimes medium/small motors, especially used, can cost a LOT less than the really big ones. I keep a list of sources for good used medium/small motors, some of which can be pulled out of existing office equipment if you care to visit the local computer or office equipment repair place and help them get rid of old junk:
As an example of how big a machine you can run with two separate, medium sized, drivers, this big guy is running two SLAm stepper controllers (3A/phase each) to move that huge, solid metal, gantry at 200ipm (could probably do 250 with a better power supply). It's a very well designed, professionally made machine, but still...
http://www.youtube.com/watch?v=Q9th4eNk50M&list=PL6F253B11C16E5AC3&index=7]First longboard on my cnc machine ~ Deck rough cut - YouTube