Messages

31

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: October 26, 2016, 05:21:19 PM »

Hi,
Controlling the spindle speed has little to do with the motor type, ac,dc,brushless, etc, and everything to to with the motor controller driving spindle motor.
It is the motor controller that  determines how you will drive your spindle motor.

What motor controller do you have? If all you have is a DC motor, what are the motors specifications, that is what is the rated voltage and current for the motor?

Cheers,

Peter

32

General Mach Discussion / Re: new at cnc

« on: September 25, 2016, 07:43:02 PM »

My suggestion is not to use the axis calibration function. It gets you close but is not accurate.
The calculations are quite simple and provide the correct values.

The Taig has a 20 turn per inch leadscrew.
You then need to take into account any mechanical gearing due to belts.

You then needs to work out the encoder resolution.

For example, if you have a 2:1 belt drive and a 250 ppr encoder, the calculations are;

tpi x belt gearing x encoder ppr

20 x 2 x 250 = 10,000 steps/inch

Alternatively, get the seller to tell you what it should be.

Cheers,

Peter

33

General Mach Discussion / Re: Modbus with PLC... unconventional problem

« on: August 24, 2016, 07:10:11 PM »

Basically IIRC, the Address is an offset from the start of the CFG#0 buffer. So, address 0(offset) is actually 8193 as cfg#0 starts at address 8193
Cheers,

Peter

34

General Mach Discussion / Re: Modbus with PLC... unconventional problem

« on: August 24, 2016, 07:06:14 PM »

Hi,

Have a look at this article I wrote. If it does not sort you out let me know.

http://www.homanndesigns.com/pdfs/Using_Modbus_with_Mach3.pdf

Cheers,

Peter

35

General Mach Discussion / Re: Normally Open VS Normally Closed

« on: August 10, 2016, 10:39:17 PM »

All commercial machines that I'm aware of use normally closed switches on limit circuits.

The reason for this is safety. With a normally open switch, your relying on the switch closing, completing the circuit and activating the input.  If a wire to the limit switch is broken (or not plugged in properly), then when the limit switch is closed, the input is NEVER activated. In some large machines this would destroy the machine.

Using a normally closed circuit, the input circuit  is closed in the normally operating condition. When the limit switch is hit and opened the input is activated. The advantage of this system is that the limit input will also be activated if a wire breaks or a connector becomes unplugged.

There is nothing to debate on this one.

Cheers,

Peter

36

General Mach Discussion / Re: problem im at a loss with

« on: August 08, 2016, 08:02:52 PM »

im sure they are, which is another problem ive been having that i havent figured out. to get the machine to have any real movement my steps per are.

X 254,572
Y 261,951
Z 263,178

which are what mach set them at using the "set steps per unit" option in settings

when i first got it going it was set at 2000 (default im guessing) you couldnt even see the table move, the only reason i knew they were was because i could see the ball screws moving just a little. top speed my machine runs about 6 IPM no matter what i do to jog settings and or percentages. so i kept going up and they would move a little faster and i was able to get an indicator on it and when i tell it to move 1.00 it moves pretty close to an inch (usually .997-.998 which i was ok with for testing)

If you are using 0.2" pitch balls screws on all 3 axes the steps per unit should be the same.
If your drives are set to 256 micro steps then the steps per unit should be 256,000.

If the above is the case your max speed will be very low. Set your micro steps to 8,10 or 16.

Cheers

Peter

37

General Mach Discussion / Re: problem im at a loss with

« on: August 08, 2016, 07:53:55 PM »

With the above information,
200 full steps (1 revolution) will move the axis 0.2". So each step moves the axis 0.2/200 =0.001"

So you need 1000 steps to move the axis 1 inch. Now, if you have a 10 micro step drive then you need ten times the number of steps to move the axis an inch, so the steps per unit would now be 10,000.

If your stepper drive is set to 8 micro steps then it is 8000 (8 x 1000) steps per unit.  By the way, there is no advantage in settings the drive micro steps to anything greater than 10.

The above assumes that you have set the native units in Mach3 to inches.

Cheers,

Peter

38

General Mach Discussion / Re: problem im at a loss with

« on: August 08, 2016, 06:33:56 PM »

Yes. I was assuming direct coupling as is common with most G0704 conversions. If there are pulleys in the drive train then the ratio will need to be taken into account

Cheers

Peter

39

General Mach Discussion / Re: problem im at a loss with

« on: August 08, 2016, 06:07:39 AM »

You can't accurately measure the steps/unit values or get mach3 to calculate it for you on a machine like this.You need to calculate it.
It's quite simple.
1. Presumably,  you are using 200 steps per revolution motors.?
2. Can you tell me the lead in your axis screws. Are they 5mm pitch ballscrews? If not what are they.
3. How many microsteps is your stepper driver set to/

If you can provide the answers to the above, I'll calculate the correct steps per unit.

Cheers,

Peter

40

General Mach Discussion / Re: problem im at a loss with

« on: August 07, 2016, 06:59:12 PM »

It sounds like your steps/unit setting is wrong in your stepper motor tuning setting
Cheers

Peter