Messages

1

General Mach Discussion / Re: How to configure two motors in one axis?

« on: September 18, 2007, 06:17:51 PM »

Hi Greg, Actually I want to know both cases:
(1)   one lead screw, two motors "pulling the same way" (one CW at one end, and CCW at the other end).
(2)   Two motors two leads pulling in parallel (for the same way).

Is your explanation for the first case (1)?

Hey Greg, by the way ¿What does X++ means in Mach?, maybe I skip it in the manual. Don´t foget that I´m a newbie.
 
 Thank you Jovimon

Jovimon

The explanation above was for case (2) particularly the homing bit.

Case (1) You would want the two motors and drives to be perfectly matched and as Brett said drive them from the same step and direction pin
 I'm sure it has been done but I would be wary of two motors driving one screw.


X++ I take to mean jog at GO speed or a percentage of it as set on screen


Greg

   Thank you Greg

2

General Mach Discussion / Re: How to configure two motors in one axis?

« on: September 18, 2007, 06:13:59 PM »

Jovimon, If I were going to try to put two motors on one screw, I'd want them to drive by a belt and not a coupling. I would also use the same step and direction pins and wires for both drives.  The reason I say this is because timing will be ultra critical if you hook two motors to one lead scerw. The belt should help eliminate this I think. I have used two motors to turn one shaft like that and it worked very well. If you want to run two shafts and two motors, just slave them, or use the same step and direction pin for both drives.

Brett

    Thank you Brett

3

General Mach Discussion / Re: How to configure two motors in one axis?

« on: September 18, 2007, 03:49:38 PM »

Not sure I understand but if its just a case that at the moment both motors run the same way it might just be a case of reversing the wires to one of the motors.
Hood

Hi Hood, As I´m explaining to Greg (above) I want to know both cases:
(1)   Two motors, one lead screw pulling the same way (one CW at one end, and CCW at the other end).
(2)   Two motors two leads pulling in parallel.

                     
                       Thank you    

4

General Mach Discussion / Re: How to configure two motors in one axis?

« on: September 18, 2007, 03:42:40 PM »

G'day Jovimon

Say one is called "X" and the other "A"

Slave them together using the menu item under "Config"

You have probably already done this.

Then go to "Homing/Limits" also under the "Config" menu, and select "Reverse" for the appropriate one.

That will do it.

This presumes you are using LPT.

If using homing switches you can have one for each motor and Mach will home each one individually.

Handy on say a gantry axis where it will confirm the gantry squareness when homed.

If using only one home switch for both slaved motors then there is a selection under "Gerneral Config"
to "Home Slave With Master Axis" and Mach will home them as a slaved pair.

Greg

Hi Greg, Actually I want to know both cases:
(1)   one lead screw, two motors "pulling the same way" (one CW at one end, and CCW at the other end).
(2)   Two motors two leads pulling in parallel (for the same way).

Is your explanation for the first case (1)?

Hey Greg, by the way ¿What does X++ means in Mach?, maybe I skip it in the manual. Don´t foget that I´m a newbie.
                     
                       Thank you   Jovimon

5

General Mach Discussion / How to configure two motors in one axis?

« on: September 17, 2007, 05:16:48 PM »

Hi everyone, I haven’t found anything in the forum about to configure Mach3 to run two step motors in one axis clockwise and counterclockwise ¿Could anybody tell me how to do it?.

      Thanks    Jovimon

6

General Mach Discussion / Re: phase drive control

« on: September 06, 2007, 12:41:55 PM »

Step/Dir control is acceptable not only for drivers for steppers, but for drivers for brush/brushless motors also. That allows to use the same controller for any type/power of motors.
The term "phase drive" control has other purpose in control theory.
Where you find this term?

Hi Lega. I guess the two posts above are self-explanatory.

                   Thanks    Jovimon   

7

General Mach Discussion / Re: phase drive control

« on: September 06, 2007, 12:40:11 PM »

I think Art tried to make the interface as easy as possible - and it is all designed to run via a 25 pin printer port. The outputs and inputs to that port are limited - I just forget the actual numbers but there are something like 14 output lines and 5 input lines. The other six are common return wires.

They are arranged in three seperate addresses in the computer, one with 8 lines, one with 6 lines and one with 5 lines.

If you use an external stepper driver board, each motor only requires two wires and a return, so using the eight line address you can drive four motors which are three axis and maybe a rotary table or someother equipment.
You would like to run the spindle motor M3 M4 and M5 (forward, backwards and stop) which takes two wires of the second address, and maybe the coolant which takes another two wires.
On the input side you need limit switches, homing switches and motor speed reading wires.

I don't mean to be unkind to Art, but the programming is also easier if you only have to put out step and direction pulses, and as has been said, step and direction are a standard which can be used by other applications

If you think of it that way, the 25 wires of the printer port are soon taken up.

If you are driving motors direct from the printer port (apart from needing some sort of interface because the port is not powerful enough to do it directly) you need 4, 6 or 8 wires to drive one motor. You run out of wires very quickly - you would need 12 just to drive three axis, which would only leave you 2 to drive all the other things you might want.

Since you need some sort of power amplifier anyway, you might as well get a driver board, which has all the on board electronics in it to control current, shut down if over heated, drive different types of motor etc. It will not cost any more - and only uses two wires per motor !!

Hi Jimpinder, you gave an excellent explanation. Sometimes some of us (Hobbysts) want to make things always from scratch, make tools usable for everything, a so on.

      Many Thanks for your attention      Jovimon

8

General Mach Discussion / Re: phase drive control

« on: September 03, 2007, 12:53:21 PM »

Yes, it is possible to drive stepper motors direct from a PC or a programmable PIC chip. I have done it myself on a PIC chip development board. You merely have to switch on each segment of the motor in turn, in the correct order for forward or reverse. You will still need some interfacing for the electronics. Computers work on 3.5 or 6 volts - steppers (to be of any use in CNC) need 24 volts at least, plus a current of about 2.5amps.

You would then have to be fairly competant at programming (with a suitable program and knowledge of PC output ports) to get all the requisite functions of a stepper motor driver board.

I can't therefore, see why you would want to do it - unless you have a cheap, cheap supply of components and copper clad to use up. The time alone to design it would be more costly than the board is worth.

I consider the stepper boards as bought ( mine are from Stepmaster) to be good value. They are competantly built, faultless in operation, and three wires gives me all the control I need. The have overvoltage protection, adjustable current provision and various switches to use virtually any type of motor.

Mine cost about £30 per motor - three hours work each - 9 hours altogether. I couldn't build an interface in that time, let alone program the computer.

Hi Jimpinder: I´m sorry, probably I´m misexplanning what I want to say or there is something that I really don´t understand (I´m just a hobbyst, not skilful on electronics). The point is that there is a shareware software (TurboCNC), that gives you two options to drive unipolar step motors (and probably many others): one is “Step-Dir” (which requires an external pulse generator)and the other is “Phase” (makes the PC generates the pulses directly). So the big question is ¿Why Mach 2/3/4 doesn´t have those options, since Mach seems to me a more robust software.

      Thanks   Jovimon

9

General Mach Discussion / Re: phase drive control

« on: September 01, 2007, 03:36:46 PM »

Do you mean frequency control of a three phase AC motor for your spindle - or what ?

If that IS what you mean, then frequency control of a three phase electric motor means you can have seamless control of the motor speed from very slow to its maximum ( and a bit over maximum if you are lucky). Wiring is very simple, and with a modern single phase to three phase inverter merely involves connecting the motor to the controller.





The controller electronically changes the frequency of the output to control the motor. There are many different makes and models on the market, and probably many available second hand.

Mach3 can control them - if the inverter you choose has the electronics to do it - (NOT Mach3). Mine does not, but I can get M3,M4 and M5 without trouble and I am working on a servo control to control the speed.

The disadvantage is that at lower speeds, you do loose some torque, so if you do a lot of low speed work, a pulley system would still be of advantage, so you could still get maximum torque at the spindle. My motor is twice the power of the original for this reason, and I haven't as yet resorted to a pulley change.

If you are NOT talking about this - ignore it !!!

Hi Jimpinder: what I´m talking is to control step motors from a PC parallel port, generating pulses from the PC directly to the phases of motors, instead of a external driver control to generates step-directions. TurboCNC does it.

     Jovimon

10

General Mach Discussion / phase drive control

« on: August 31, 2007, 10:41:52 PM »

Hi everyone, ¿what are the advantages and disadvantages of the phase drive control? ¿Why Mach3 doesn’t include this type of motor control?

          Jovimon