Messages

1

Mach3 and G-Rex / Re: (STP/DIR) Manually driving the stepper motors using Raspberry Pi

« on: November 24, 2018, 08:44:49 AM »

Sack that last post, found one.
Im gonna trial using the setup you suggested.
Might be back in touch later if i get stuck.

Cherrs

2

Mach3 and G-Rex / Re: (STP/DIR) Manually driving the stepper motors using Raspberry Pi

« on: November 24, 2018, 08:37:44 AM »

Hi Craig

I'm looking to get the 4/64GB lattepanda but it says there's none in stock on the dfrobot site.
I checked elsewhere and Amazon have them but its expensive at £425 (GBP).
They have a 2/32GB for something like £115 (GBP), would still work?

Cheers
Dan

3

Mach3 and G-Rex / Re: (STP/DIR) Manually driving the stepper motors using Raspberry Pi

« on: November 23, 2018, 08:14:27 AM »

Hi Craig

Wow, that's excellent info, i had no idea there was so many options.
Looking at them all now, think I'll definitely use one of those.
Thanks for adding all that extra detail - really helpful.

Cheers
Dan

4

Mach3 and G-Rex / Re: (STP/DIR) Manually driving the stepper motors using Raspberry Pi

« on: November 22, 2018, 05:09:33 PM »

Hi Craig

The drivers do indeed have dip switches on them, so there will be some microstepping.
I'm gonna gave a bash at this over the next couple days.
Thanks again for clearing all that up so concisely.

Cheers
Dan

5

Mach3 and G-Rex / Re: (STP/DIR) Manually driving the stepper motors using Raspberry Pi

« on: November 22, 2018, 04:27:55 PM »

Hi Craig

Thanks for the reply, ramping up makes perfect sense, otherwise the magnetic field inside the motor will be moving faster than the motor can go from a standing start.

I cant use Mach 3 because it needs to be idiot proof. I want to use it as a soldering machine and there's limited space, so i want to keep it as compact as possible. The pi fits inside the little control box with 2 little joysticks and a button that turns the heat on and off. Its actually a resistance solder process so it heats up instantly. Probably going off topic now.

So to summarise:
I just need to control the motor using a square wave, there's no PWM required?
The frequency of the waveform controls the speed of the motor?
Start the frequency slow and ramp it up.

Thanks again.

6

Mach3 and G-Rex / (STP/DIR) Manually driving the stepper motors using Raspberry Pi

« on: November 22, 2018, 03:14:52 PM »

I have CNC router along with its driver unit. I dont want to use it as a router, i'm hacking it to move manually using 2 joysticks. One joystick is a 4-way and controls the X and Y axis. The other joystick is a 2-way and controls the Z-axis.

I want to keep my work to a minimum, so i plan to drive the CNC from the parallel port that would usually get signals from the PC (i.e. Mach3). It would appear there are only 3 wires from the parallel port to each of the stepper motor drivers. I assume these are: STEP, DIR & GND?

My question is this:
Assuming that is the only signals I need, what type of waveforms do they need?
From what i've read, DIR is just a standard logic signal (5V or 0V). Is that correct?
It would appear the STEP signal requires a pulsed input? That would make sense.
So assuming it needs a pulsed input, what is the frequency (25kHz)?
Also, what would a typical pulse train look like in order to get the motor moving?
I know the Pi is 3.3V, i have a driver converting them all to 5V.

Any help much appreciated. I'll try post some pics and vids later.

10-4 Rubber Ducky