Hello

[luke11cnc]

welcome matt have you any designs yet ??

James

[matt-b2]

Hi,

In terms of mechanical design, I don't have anything drawn yet - Just lots of ideas floating around in my head. The basic spec. for the machine is as follows, although subject to change:

• 4-axis, cartesian, overhead gantry providing open access from all 4 sides to the machine's bed where the PCB will be held. Two opposing sides will be used for mounting component feeders.
• 500-600mm working envelope for X and Y axes. >25mm for Z axis.
• X & Y axes actuated with 1605 ballscrews and SY57STH76-3008B Nema 23 stepper motors with back mounted 1000 line encoders - Closed loop, hybrid stepper/BLDC microstepping algorithm.
• Z axis cam actuated with a stepper motor (TBD) - Open loop, microstepping.
• C axis actuated with SY28STH32-0674B Nema 11 stepper motor - Open loop, microstepping.
• Magnetic automatic nozzle holder/changer.
• Vacuum provided by Nitto DP 0110 air pump.
• Component alignment to be performed optically with upward facing USB or ethernet (TBD) camera.
• Fiducial based board alignment to be performed optically with downward facing USB or ethernet (TBD) camera mounted on end effector.
• 150W Linear PSU, BS EN954-1 Category 2 emergency stop circuit.
• ARM Cortex-M3 based open and closed-loop motor drivers.
• ARM Cortex-M4 based motion controller with USB or ethernet interface (TBD) to host PC.
• Linux-based host software, initially command-line/XML based with a GUI to be developed later, probably using QT.
• 8, 16 and 24mm tape dispensers.
• Vibrating tube dispensers.

Matt.

[Jonathan]

What sort of feedrates and resolution do you require? Pick and place machines are generally quite fast so you may want to consider using 1610 as that will get greater acceleration and speed without using a timing belt drive, or even with. Gives more options...depends what you are aiming for.

I'd like to hear more about how your method for driving the stepper motors closed loop?