[Steve-Tee]

Howdy Kuikkap,
That is the sort of thing that we like to see here, innovation .
It seems that the humble stepper motor can be used for so much more than ruining hours of CNC work .
Just one thing though, can you please tell us what the oscillator is intended for?
I see that it provides a sort of 'ripple voltage' for the common point of the stepper coils.
Is this intended to resolve issues regarding hysteresis perhaps?

Thanks kindly,
Steve.

I tried to make a jog encoder out of a small stepper. I had an idea of (mis)using 74hc14 schmitt trigger to clean up the pulses.

The thing works pretty well.

Schematic applied.

[Steve-Tee]

My pendant has been of great assistance of late. As it lets me drive the motors without the need for a computer, I have been able to use it to help me set my machine up.
It let me confirm the Z axis in a matter of minutes, by allowing me to move it between extremes while I looked out for problems.

Then, it allowed me to correct whipping problems with the 16mm leadscrew of the Z axis.
At 30 turns per second, this was quite entertaining .

Finally, it let me discover that I had really messed up on my design of the Y axis .
Still, it made life easier to find this mechanical fault now, instead of later .

One of these days, I should make a video of the pendant in operation, as it's a great way to let the machine carry out simple tasks without computer assistance, or is that 'hindrance' .

Cheers and beers,
Steve.

[kuikkap]

Howdy Kuikkap,
That is the sort of thing that we like to see here, innovation .
It seems that the humble stepper motor can be used for so much more than ruining hours of CNC work .
Just one thing though, can you please tell us what the oscillator is intended for?
I see that it provides a sort of 'ripple voltage' for the common point of the stepper coils.
Is this intended to resolve issues regarding hysteresis perhaps?

Thanks kindly,
Steve.

Thanks.

Oscillator circuit provides a voltage level which is exactly in the middle of the hysteresis zone. C1 pumps between hysteresis limits and the low pass circuit averages it to constant dc voltage. Note that I initially forgot to draw the low pass circuit components. So schmitt triggers are used as 1 bit memory or RS-flipflop. Two steppers can be connected to 1 IC.

I first thought to make simple resistor divider to make middle voltage, but according the datasheet there was too much tolerance to make that work reliably.

[Steve-Tee]

Howdy Kuikkap,


Ahhh, yes, now I see it. As I was reading your message, the penny dropped into place .
I remember doing something like this with logic devices that I needed a reference for. It was an unusual approach but, like you say, it accomodates the relatively wide range of hysteresis bands in these chips.

That's one of the things I love about the interweb, you get to see some very clever ideas .

Great work .


Best wishes,
Steve.

Thanks.

Oscillator circuit provides a voltage level which is exactly in the middle of the hysteresis zone. C1 pumps between hysteresis limits and the low pass circuit averages it to constant dc voltage. Note that I initially forgot to draw the low pass circuit components. So schmitt triggers are used as 1 bit memory or RS-flipflop. Two steppers can be connected to 1 IC.

I first thought to make simple resistor divider to make middle voltage, but according the datasheet there was too much tolerance to make that work reliably.

[flyboy1015]

I've been looking at pendants for some time now. My most recent thought is that I could buy a low-cost game controller from my local Wal-Mart and dissassemble it. I can then build my own pendant hand piece and insert the guts of the game controller inside while connecting the electrical connections to the pads on the circuit board and the other end to buttons on the pendant. I would configure keygrabber for Mach3 and have at it. I'm already using the game pad, I just need to reconfigure to a friendlier configuration. Thoughts? Maybe I should build these and sell.

[neilw20]

I've been a bit busy.

Another thought for using the stepper as an MPG, seeing as how we like a scale on them, is to motor the stepper when axis is running in cnc mode.

Didn't you notice how the handle on the mill would rotate when feed engaged?

Why not put the MPG in the right place so the look and feel of a manual operation is as good as it was. You could even sense the load and stiffen up the MPG if you hit a hard spot. That would make for good delicate work.

I am now using 0.2mm drills and now if the gib is slightly loose then the tip of the drill can move visibly sideways by half a diameter. !

Cheers.

[chrbau]

Or you could go for a solution without electronics, just some microswitches and a cam on an axel.