I am in the process of converting a Grizzly G507 mill/drill to CNC. I would like to use the black box for control and Openbuild control software. However, I have some concerns that it might not handle that kind of load. I am using Nema 23 motors with 280 oz holding force. The lead screw is Acme 10 threads per inch. One revolution of lead screw is 2.54 mm. Gear driven 2.5:1 to lead screw. Power supply is 24 Volts. My questions are: Can the black Box handle that power? Where would I start with parameter settings? ie: $100, $101, $102 (196.8 is the setting now) $110, $111, $112 (2000 is the setting now) $120, $121, $122 (50 is the setting now) Thanks for yor help.
I use LinuxCNC, NEMA 34s and ballscrews on my Grizzly conversion, so I can't comment much there. Most of those grbl settings will really need to be calculated once you actually have the machine moving around, depends how the motors perform under load- might need to adjust microstepping, acceleration, etc. Just bear in mind that grbl as it stands doesn't have backlash comp, so you'll have to make anti-backlash nuts and really tighten them up, or use some kind of g-code backlash converter. It's not impossible to use it on heavy machines, but it's not exactly designed for it either; it also doesn't have tool wear comp or tool offset tables. Some of these additional features are provided by advanced g-code senders, of which OB CONTROL is not one; it's designed for beginner users of simple extrusion-based machines. You'll have to come up with some workarounds if you intend to use it as a semi-standard VMC type setup.
I make that 1.016 mm per rev, Blackbox defaults to 8x microstepping, so my calculator shows... steps per mm: 1574.803150 or 0.0006349999999999999mm per step BUT you quickly run into the max step per second limit of 33000hz, so top speed will be limited to about 1100mm/minute unless you reduce the microstepping. what current are the motors rated for? the blackbox can do up to 4amps peak per motor, which means you dont want to run at more than 3amps per motor. so, if the motors want more, then the Blackbox is the wrong solution. as for tool offsets and so on, those are really only useful if you have an automatic tool changer, I would not view that as a problem here. backlash might bite you though, in which case I would go for LinuxCNC
I'm literally running the mill right now using LinuxCNC's tool offset tables without an ATC. M6 is my new best friend.
