Messages

21

General Mach Discussion / Re: Can you wire a proximity sensor directly to a motion control board like a pokeys

« on: April 13, 2018, 01:42:39 PM »

If the input normally takes 5v as a signal, you have to pull up the pin and set the input to active low.
I have a Stepper3 Ether mach CS controller and, after modifying it by removing the input led's, use npn proximity sensors at 12v feeding the inputs through a 390 ohm resistor. The sensors have a 10K internal pull up. This gives about 3.7v at rest, enough to take the pin high, and it goes to 0v when proximity occurs.
I should note that the controller has 4.7K pull down resistors on the inputs. I removed the leds because they were also pulling down the pin with a 39 ohm resistor making them unusable. Long story.

22

Mach4 General Discussion / Re: XHC Mach4 USB motion board warning and info

« on: March 12, 2018, 05:54:52 AM »

I uploaded the driver on page three. I just got an Ether-Mach-CS motion controller so I'm done with the XHC.

23

Mach4 General Discussion / Re: Possible Feed Rate Bug?

« on: February 24, 2018, 06:27:12 PM »

I wonder if the program is compensating for tool diameter, trying to figure a cutting speed (tip speed) rather than feed rate (tool speed).

24

General Mach Discussion / Re: I need use the motor brushless with 5 axis stepper card

« on: February 20, 2018, 05:21:25 PM »

Maybe use 1K resistors instead of 250 ohm. I don't know what the expected load is there, probably high impedence.

25

General Mach Discussion / Re: I need use the motor brushless with 5 axis stepper card

« on: February 20, 2018, 04:15:39 PM »

OK. In previous post I said connect red from esc to +5v on arduino. Don't do that.
The red wire from the small plug is to feed voltage from the esc battery to a radio control receiver, and the adruino doesn't need that.
All you want to do is generate a pwm signal like the servo tester does, and reference it to the 0-10v from the controller card.
You have an arduino uno or nano? plenty of videos on you tube how to program what you want. The white wire goes to a pwm pin on the arduino and the black goes to grd. clip the red half way there and insulate for later splice and re-use.
A voltage divider is a series of resistors, say two 250 ohm resistors in line. connect the ends to 0-10v out and motion controller ground or 0 volts.
Splice to the wire between the two resistors (250 ohm on either side of the center point)  and put that to an analog input of the arduino. connect the arduino grd to motion controller grd.
Program the arduino to get analog input and control pwm output on whichever pin you chose. Search you tube for arduino pwm control.
Should be a piece of cake.
You could maybe use a servo shield to use a canned example of pwm control.

26

General Mach Discussion / Re: I need use the motor brushless with 5 axis stepper card

« on: February 20, 2018, 02:49:05 PM »

To use it as the spindle you need to feed the ESC the correct voltage with enough amps, making the power supply a major expense, unless you use lipo batteries as it was designed for. Up to you, but it would be easier to get a 120v mini router and adapt it to your machine. This gives you a collet to hold tools too. How are you going to put a collet on the brushless motor?
If you really want to do the brushless, you need to set up an Arduino ($12us) and program it to deliver a pwm to the ESC with a potentiometer on an analog input. Or just use the servo tester. If you really want to control the motor from the motion controller, you could take the 0-10v output spindle speed control signal (if it has that), put it through a voltage devider ckt and send 0-5v to an analog input of the Arduino, then generate the pwm based on that. Easy to do the control, but why would you want to?
Go nuts man.

27

General Mach Discussion / Re: I need use the motor brushless with 5 axis stepper card

« on: February 20, 2018, 11:12:23 AM »

What do you want to use the brushless motor for?
You need a pwm output to control the ESC, and you might not have that on your stepper control card.
If you have an Arduino board you can experiment generating a pwm signal and run the brushless motor. The pwm signal goes to the white wire and grd goes to the black. The battery (or dc power supply) for the ESC goes between black and red. That would be +5v to the red from an arduino. This is a good idea to help you learn how this stuff works.
Observe voltage limit of the brushless motor, sometimes listed as 3S, 4S etc. This refers to the size (number of stacked cells) of LiPo batteries. The current draw of an ESC is quite large compared to common power supplies capability, so using a brushless motor in place of a stepper is a bad idea. Typical ESC might be 40A, and go up to 160A and higher. I have a water cooled brushless motor that uses 4S batteries and a 200A ESC for an RC boat. A stepper motor might draw 3A.
A brushless motor and a stepper motor are very different with different intended use. A brushless motor is a 3 phase motor, like a blower motor, so using it as the spindle motor of a cnc machine is it's only choice, and a bad one. They work very well spinning a propeller on a quad-copter due to large power developed and variable speed, and the ability to use a battery.
Stepper motors are not intended for fast, continuous rotation like a spindle motor or a blower motor. They move to an exact position based on the number of steps ordered, usually 200 steps per revolution (or a multiple of that). This is why they are used to move the axes of a cnc machine ... precise positioning at a slow rate. A 24vdc 15A psu are enough for three of them, and way cheaper than batteries.
Learn how 3 phase motors work (the 3 leads circled in black above) and how radio controlled models are controlled (small plug circled in blue above).

28

Mach4 General Discussion / Re: Jogging and DRO errors

« on: February 12, 2018, 02:01:30 PM »

I think I know how to fix it.
Send a command for G0 x1.
I know Mach4 is very complex, but it's a little odd anything other than that would happen. Hence my comment about fuzzy math. Giving direct commands to move gives perfect DRO results.
In my testing the DRO result after a jog changed with accelleration settings changes. That should not be. Unless they've got something like Bernoulli's equation providing the result to send. KISS?

29

Mach4 General Discussion / Re: Feed rate not steady

« on: February 10, 2018, 05:39:02 PM »

Hi Craig
I'm definitely ditching the xhc. Too many quirks. I don't understand the give and take between the motion controller and Mach4 output, but there seems to be something going on. The sound of the stepper motor varies in a pulsing fashion in exact time with the blinking communication light on the mc. I thought it was passive and just took orders, but it's becoming moot.
Right now I only have an arduino mega with grbl on it to play with as an alternative, and it is crisp and precise by comparison. Partly because Universal G code Sender does just that. It doesn't interpret the commands so what you ask for is what happens. It also prints the dialog on the command screen for every transaction, and the card reports back what it's doing. It's really very friendly by comparison, and I don't see right off what Mach4 can do that this thing can't. Except maybe edit the screens. It's freeware too. $40 for a Mega and you're rockin.
Are there any real advantages to running mach4 for a casual hobby mill?

30

Mach4 General Discussion / Re: Feed rate not steady

« on: February 10, 2018, 10:39:48 AM »

It's an XHC usb motion controller.  The variation I'm seeing is in the Mach4 DRO for feed rate, and it fluctuates from approx 9.5 to 10 when set to f10.  It's hard to read bcause it never settles down.
The motors are loose on the bench at the moment, just hooked up for testing, and the sound is all I have to go by at the moment.
I thought feed rate from Mach4 would be a fixed value based on velocity selected and feedrate %