Etch a Sketch style power feed

D

Driveslayer45

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Good morning.

Does anyone know of a pwm controller with forward and reverse on the dial so that you can effectively use the power feed of your meal like an etch a Sketch?
 
haha i knew that was coming, and its my own fault for not heading it off..

but no, just a speed dial that allows the forward or reverse of the motor based on which way off center the dial is moved. the farther the move the faster. perhaps a better description is something akin to the steering knob on a radio control car. turn the knob CW car turns right, CCW car turns left. turn the pwm knob CW x axis feed right, turn the pwm knob CCW x axis feeds left. knob center x axis doesn't move.

i am not interested in the complexities or expense of converting and setting up my mill to be a CNC, but i could certainly envision a considerable amount of joy machining a part etch a sketch style .. certainly i am not the only one who has thought of this...

i have thought of using something like a servo tester from the RC world but they cannot carry the volts or amps needed.
 
It should be a fairly simple design to come up with. A computer joy stick would be a good starting point. The ones that I have seen used a pair of potentiometers for each axis with a mechanism to activate only one of the pots in each pair at a time. Some 555 i.c.'s could be used to convert the potentiometer resistance to PWM signal which could be amplified and fed to the motors.

Another approach would be to use an Arduino based circuit.
 
I'm thinking V/F converters, plus trimpots for zero and span, maybe offset too, plus output drivers
Need some brain grease
 
While that sounds good I'm thinking simple controllers, basic readily available motors. Meat and potatoes solution.
 
The function of motor speed increasing as stick is moved further, and return to zero at center, isn't exactly trivial to do
You're talking about a non-linear action
 
You could use Mach 3 or 4 software for that. An unregistered demo should work unlimited for jogging. The demo times out after so many lines of g code so if just jogging wouldn’t time out.

Would need a breakout board to go from parallel port or usb. Then two stepper controllers, stepper motors and a power supply. And a mechanical link to your machine. Very doable. On eBay you can buy all that is needed at the same time.

For jogging control you can use the arrow keys on the keyboard. Or get a keyboard simulator and connect a joystick to that, connecting the joystick to the movement keys. Also Mach 3 is able to be controlled with a PlayStation controller.

Also with Mach 3 or 4 can add a usb pendant with a hand wheel. The hand wheel has the ability for variable steps per pulse so can make it go short distance with each click (like when you are close to your part) and longer when need to move faster.

Download the software and look it over, it is free to demo.

What you are wanting to do is what many people with a CNC machine do for a simple part not needing to code for that.
 
Hmm, sounds like my ambitions are taking me into waters I hadn't intended to tread. Thanks for the input everyone. I need to reevaluate where I want to go with this.
 
Driveslayer45 said:
... turn the knob CW car turns right, CCW car turns left. turn the pwm knob CW x axis feed right, turn the pwm knob CCW x axis feeds left. knob center x axis doesn't move.
Click to expand...
Maybe you want not a speed control, but a POSITION control. I've done it with a stepper motor and a computer mouse (the old
Apple mice give outputs that can be amplified and fed to a stepper motor). If you want to do it for machining,
it's susceptible to backlash unless you have a position encoder, which means the feedback to an adjust motor
has to go through a computer...

There's no 'feel' to the knob the way I did it, and the zero-center feature didn't apply (there's no real 'center' to a mouse
position). Most mechanical ball mice or trackballs have the right kind of encoder to implement the stepper-motor
connection trick, but it'll lose 'zero' every time it powers down.
 
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