New design for a CNC engraver/etcher/scratcher ... ???

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11 Nov 2023 23:59 #285143 by tommylight

Oh, so Z axis only serves the purpose of probing the material. The rest is done via spindle output.

No and no, there is no Z axis, there is a pressure servo.

I assume the Z output from the Gcode signal is script-converted into a S1 - S1000 signal to drive the pwm out.

Again no, although this works, it causes way to much vibration due to start/stop to change spindle speed.

Can you post your files?

Of course, see the second post.

Not sure how to handle the table flattening probe.

I have no idea what this is about? There is no probe and there is no flattening of granite/marble/glass material, they are flat, always.

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11 May 2024 22:49 #300409 by tommylight

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06 Jun 2024 06:29 #302435 by Lockwood
Fantastic design, do you have any details on the electronics and the motor used to swivel the head please and how to drive this movement? Many thanks Mike

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06 Jun 2024 20:23 - 06 Jun 2024 20:24 #302487 by tommylight
I am not in the shop now, but in short, the "pressure" motor is
-a 3 phase BLDC motors with it's own electronic controller taken out of the old photocopiers,
-there are many versions and sizes of them,
-form 5 to 10 pins,
-all signaling is sinking type or "active low", meaning connect to ground to activate
-all have the pinout printed on the board,
-older ones are pure PWM while new ones require also a clock signal,
-some are single direction while some are bidirectional,
-and most of them can be easily used for this purpose/machine,
--The PWM ones require 5V, 12-24V and an inverted PWM signal
--The ones requiring clock signal have a self check feature, so mostly work with only 12-24V supply and one of the pins tied to ground, this pin will spin the motor for about 2 second and stop, and has to be disconnected and reconnected to spin again. This pin is used as inverted PWM but scaling must be set to about max 85-95% PWM to keep the controller from tripping and stopping the motor after 2 seconds.
--for inverting the PWM pin i use a single 220 OHm resistor and a single transistor, any NPN transistor works, resistor connected between base of transistor and PWM output from PC or Mesa board.
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hackaday.io/project/5236-savin-c2020-teardown
Last edit: 06 Jun 2024 20:24 by tommylight. Reason: more info

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