Initial design advise wanted

[fifa]

Drive should be defined based of the performance.

Gantry mass play role, however if acceleration is 1200steps/second assuming 200 steps/rev this means 6 rev/s, acceleration of the gantry will be 60mm/s2, assuming gantry's mass is 100 kg - results 6N inertia force ... Correct designed drive can run additional load of human body (100kg) without problem - I am testing drive in this way.

For better understanding: side force of 6mm mill can not exceed 40N, typically it is bellow 25N.


For hobby machines main inertia forces (torques) are defined with spindle diameter. Relation between Spindle Inertia and its diameter is power of 4 (double diameter requires 16 time higher torque), same rule is applying for pulleys and gears. All others relations are linear.

Do not expect stepper motor to run more than 10m/min. It is hobby machine. 10m/min means 1000rpm (assuming 10mm pitch), which is ca 7kHz with half step mode. Not an issue for cheap drivers. For 2 motors you need ca 40kHz cheap Arduino type breakboards can do the job (96kHz).
However they are not good enough if controller need to do also micro-stepping.

Motor performance depends on motor inertia. Therefore motor rotor inertia shall be as big as possible (rotor accumulates an energy). With servo you can afford ratio up to 4 with stepper it shall be always less than one (to avoid risk of loosing steps)


Start designing from "top" , do not go too much in details.

2kW main spindle is quiet (no cooling fan), it is strong enough to continuously cut oak with 10 mm dia 8 mm deep speed aprox 4m/min.

I am assuming you have in mind cheap Chinese spindles. Front bearings are small (15mm dia), consequently bearings are loaded "eccentrically" - not all the balls take a load, some of them are unloaded. If ball is unloaded it start skitting (due to friction between ball and lubricant), consequently bearings worn out relatively quick.

Regarding noise: Whatever you will do, most likely workshop has a window, which will work like horn. The best way is to "absorb" as much noise as possible (for example carpets on the wall - but then walls becomes also dust collectors...). Machine housing (envelope) will do the job.


regards