Hi,
I think we may have to revisit some of those settings. A two phase stepper has 200 1.8 degree steps per revolution. A conventional driver set to 'full step'
when pulsed 200 times the motor will turn one revolution. Most drivers offer microstepping which subdivides each full step into commonly 4,8,16 and sometimes
more microsteps. For CNC routers microstepping allows a very much smoother motion than full stepping which can be quite harsh. Most use 8 and sometimes
16 microsteps per fullstep. Do you have any documentation for your controller? You will need to set the dip switches for 8 microsteps.
With 8 microsteps now the driver will be pulsed 1600 times for the motor to complete 1 revolution, I'm going to guess that your ballscrews have a pitch of 5mm
per rev and that the steppers are directly connected, ie no belt reduction, 1600/5=320. That is to say that 320 pulses would cause the motor to turn 1/5 of a
revolution and the axis to travel 1mm. You might consider that the resolution of your machine is 1/320=3.125um. That is an optimistic assumption, for a number
of reasons the practical resolution will be about 12.5um, just a bit over 0.01 mm, pretty damn fair!
Stepper motors lose torque in a big way the faster they go. Probably fair to consider their max speed to be about 500 rpm. You can of course make them go faster
but unable to drive an axis with authority, ie it will lose steps or stall and be generally hopeless for CNC. 500rpm x 5mm pitch=2500mm/min, so your velocity setting
sounds about right. A general rule of thumb for acceleration is about 10% of velocity so 250mm/s/s.
Unfortunately the rewiring did not result in testing the drivers as I'd hoped. You changed the wires from the output of the drivers to the motors. I was hoping you
could change the inputs to the drivers and so establish whether the A and X axis drivers are good and the same. Because the inputs to each driver are determined
by the copper traces of the circuit board you can't realistically change them.
Can you take some close up pics of the board, I want to see if there are any markings which would indicate the microstepping available with different DIP switch
settings? Can you also check or measure the pitch of the ballscrews. Turn one by hand 1 turn and measure how far the axis moves. Be accurate. The difference between
0.2 inch, a common imperial pitch and 5mm, a common metric pitch is only 0.08mm, ie not much between them. Can you post any manual you got with the
machine?
Craig