Starting to design out my build, looking for critique

[AndyUK]

Normally I would now lay-out what was on my mind, when it comes to next steps, but I cannot come up with anything concerning the CAD model, it looks pretty much done to me. What I need to now look into, however, is the electronics side of things: Find out what I still need in terms of controllers, motors, Power delivery, etc. and get some rough pricing, as well as model it into the CAD as needed. Where would be a good way to start here? For the gantry and machine design there were some helpful collection threads on here, comparing different gantry designs, for example. Is there also something like this when it comes to the electronics?

Suggest you start here:

http://www.mycncuk.com/threads/1524-...otor-do-I-need

Once you're up to speed with the description, open the spreadsheet and customise to your needs (its setup for a smaller machine). Find reasonable values for your cutting forces and repeat for each axis in turn (increasing the moving weight as you go - ie. Z has a small moving load, Y has slightly more, X even more). I rebuilt the sheet from scratch to show all axis at once with individual inputs which helped.

Next is the leadscrew calcs - lookup typical efficiencies of the system you're using, and what each of the measurements mean. This will give you screw inertia and critical speeds. From your screw pitch, you then have your maximum permissible speed on that axis. Tailor the ballscrew configuration until you're happy with the maximum speed.

Now you have to decide what max cutting speeds and rapid speeds you want. I aimed for 5m/min rapids - some people here can get 7.5m/min. Cutting speed depends on the material (as does the cutting force).

Then you can start plugging motors into the spreadsheet. Find a few example motors online, look at their specs, and put them in the sheet taking best guesses where needed. Then play with your power supply settings, and the sheet will tell you if the motor is up to the job or not. This is how I came to the conclusion that NEMA23s on each axis were more than suitable for my application.

The motor drivers are then somewhat dictated by the current required, and the PSU is calculated by summing the maximum currents on all axes, then multiplying by a stepper usage factor (I think its 2/3rds? but you'll find this in the Power Supply threads). The voltage for the PSU is dictated by the inductance of your motors - the sheet will tell you an ideal voltage, and the drivers will have a maximum voltage - aim somewhere between those two allowing for variations in mains supplies.

Rest of the electronics are essentially personal preference. Many ways to skin a cat...