Hi,
also just a quick question when i press "ref all" all 3 axis barley move to the home switches any idea what i might have done
That has to do with homing also call referencing and it is adjustable. Don't bother with it until you have the motors
dialed in. If you cannot move a precise distance then you are going nowhere.
Try this MDI:
g0 x100
x0
x100
x0
x100
x0
x100
x0
x100
x0
Does it move backwards and forwards, 100 mm per move? Does it move flat stick?
If so now try the Y axis:
g0 y100
y0
y100
y0
y100
y0
y100
y0
y100
y0
y100
y0
If the Y axis is moving backwards and forwards OK then try some linear interpolated moves:
g0 x100y100
x0y0
x100y100
x0y0
x100y100
x0y0
x100y100
x0y0
If all these work OK then you can start thinking about tuning your motors. By tuning I do not mean fiddling with the
Steps per Unit. Those settings are now made and unless you change motor settings or ballscrews you shouldn't ever have
to touch them again.
I would concentrate on acceleration first. Acceleration (linear) is equivalent to torque (rotation) so to explore the
torque capacity of your motors at various speeds is where you want to go. You might achieve a high speed say, but have
to dial back on the acceleration in order to avoid losing steps. I think that is a mistake, increase acceleration as much
as you can and THEN increase max velocity until the onset of losing steps.
Try quadrupling your acceleration to 1000 mm/sec
2. Run the same test as above. How did it go?
If it went well double the acceleration again, now up to 2000mm/sec
2. It is now very likely your machine
is flopping around like a fish. Industrial production machines have accelerations of 1g-5g that is 10,000mm/sec
2up to 50,000mm/sec
2. Hobby machines cant usually get within a bulls roar of that and they try to throw themselves
around the room if you try.
What you are trying to achieve is the highest acceleration your motors can deliver consistent with the machine not flexing
alarmingly AND your heart rate stay below 200BPM! You might chose to back off from max by 10-20% and allow some headroom.
Now you want to start increasing the maximum velocity until it starts losing steps. Given that your steppers are closed loop
the drive will try (try being the operative word) to catch up on lost steps. Usually what happens if it starts losing steps the drive
faults 'following error'. You know then that you hit the limit. Back off 25% and run your tests again. What you are trying to
achieve is the maximum RELIABLE speed with the steppers having still plenty of torque to accommodate both good acceleration
and cutting forces.
A thorough investigation of your motors and machine capabilities will probably take a couple of days. Try to be methodical about it.
Often, once you tune your machine, those settings will stay the same over the life of the machine. It really does pay to explore
the limits. So many machines around the globe are actually way more capable than the owner realizes and he will merrily be
using but a fraction of the machines capability because of his inexperience/impatience/disorganization at the time he set those
limits.
Craig