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Topics - chrisjh

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General Mach Discussion / Mach3 Spindle Speed Problem
« on: October 28, 2008, 08:12:21 PM »
I am using Mach3 V3.041 with a Smooth Stepper in PWM mode.  Base Frequency is 1000 (but the problem persists whatever Base Frequency I use).
The problem is very consistent and it doesn’t matter what method of requesting any Spindle Speed.  (MDI using M and S commands or from any Spindle Toggle Buttons on any Mach3 Tab).

The problem with the spindle speed is as follows:

Select a speed (say 1000rpm). Spindle Override reads 1000 same as Spindle Speed and SRO reads “00”.

Toggle the spindle on.  The actual speed of the spindle always starts at a slightly higher speed than that requested. 

Pressing “Reset” under the Spindle Speed Tab always brings the speed back to correct requested speed and subsequent requests for speed changes (via Spindle Override or actual commands for a different speed) from there on are correct and consistent.

It appears that Mach3 is in some form of Spindle Override (approx +10%) when first started.  I first noticed this problem a couple of years ago but ignored it and learned to live with it with my mill.  However I and building a cnc lathe with a VFD controlled Spindle Motor and want better control over spindle speed.

Also there is another dialogue Tab under the Spindle Speed Tab labeled RPM.  It always reads “0” regardless of what I do with Spindle Speed and it does not accept any characters typed into it even though it changes background when selected. So I ignore it.  What is the purpose of this “RPM” Box and should it indicate something?



General Mach Discussion / VFD Forward/Reverse Relay Control in Mach3
« on: October 11, 2008, 02:26:06 AM »
I am planning a CNC Lathe conversion based on the following Electronic Components:
1.    Smooth Stepper
2.   CNC4PC C23 Breakout Board
3.   Danfoss VLT Micro Drive FC51 VFD http://www.automationdirect.com.au/Welcome/drives/Danfoss.html
4.    Mach3

All was going well until I was planning the Forward/Reverse function for the VFD.  The Danfoss VFD has "Start" and "Reverse" Input Pins which can be selected via external relay contacts.  The VFD supplies 24VDC out for the purpose of being switched to various Input Pins including "Start" and "Reverse".
I am interpreting the "Start" as being "Forward" and “Reverse” as being "Reverse".
I plan to use the PWM function within Mach3 in conjunction with the CNC4PC C23 Breakout Board to generate the 0 - 10VDC speed control for the VFD and to utilize the 2 mechanical relays to select Forward and Reverse.  According to the Silkscreen on the C23 Breakout Board, the 2 relays are associated with Pins 1 and 16 (presumably of the Port 1 Ribbon Cable Connector).

I configured the Ports and Pins within Mach3 to do this by:
1.   In the Spindle Setup Tab, enabling M3 and 4 to O/P 1, Use Motor Control Output Checked, PWM Control Checked, Disable Relays Unchecked, and PWMBase Freq to 1000.
2.   In the Motor Outputs Tab, enabling Spindle, Port 1 Step Pin 14, with no direction Pin selected.
3.   In the Output Signals Tab, enabling Output 1, and Selecting Port 1 Pin 14.

The problem I have is that I don’t understand how to associate M3 with Pin 1 (thus energizing one relay for “Forward”) and M4 with Pin 16 (thus energizing the second relay for “Reverse”).
Can anyone suggest a way to do this or am I barking up the wrong tree?



Share Your GCode / Soft Start for Spindle Motor G Code Routine
« on: September 09, 2008, 08:34:07 PM »

I have a Syil SX3 Mill fitted with the original Seig Spindle Control Boards.

Later boards have a "soft start" feature for the spindle speed. I personally don't like the later boards because of the slow accelation rate to spindle speed. The soft start feature appears to emulate pushing of the front panel up arrow buttons and is set in firmware. It is far too slow for the spindle to come up to full speed of say, 3000rpm.

The original boards do not have a soft start feature and this places a lot of stress on the spindle motor and belt when a speed of 3000+rpm is selected under G Code Control.

When is issue S3000 from 0 RPM, my machine instantly overshoots the requested set speed and settles back to 300RPM.

I have a soft start G Code solution which meets my requirements which I tested this arvo as follows:

(Soft Spindle Start Template)
(This routine brings the spindle up to 3000 rpm in small steps)

(CJH 27Jun08)

G00 G17 G21 G40 G49 G50 G64 G80 G90 G94
M6 T6 (5mm Drill)
M3 S750
G04 P100
G04 P100
G04 P100
G04 P100
G04 P100
G04 P100
M8 (Coolant on)
G00 Z10
G00 X0 Y0 Z3

G00 Z15 F2000

M5 M9 (Spindle and Coolant Off)

G00 X0 Y0 (Return to start position)

The "G04 Dwell in ms" config settings under "General Config" in Mach 3 or Quantum must be selected for this code to work. I am using Quantum at the moment.

What the code does is to start the spindle at 750rpm, then waits (dwells)for 100ms (0.1 seconds), then increases to 1000rpm, then waits for another 100ms, and repeats this in 500rpm increments until 3000rpm is acheived. The speed ramp up to 3000rpm happens very quickly and smoothly without the stress on the motor and belt.

You can experiment with G04 P********* dwell times and the speed start speed and increase increments to suit your machine.

Hope is is useful to others.



Hi All Syil X3 Mill Users,

Syil X3 Mills are Seig X3 Mills converted to cnc.

At the attachment below you will find the procedure that I used to calibrate the spindle speed of my Syil converted X3 Mill. The procedure calibrates the speed requested by Mach3 to the actual speed of the machine.

I was always annoyed that I could never attain the maximum 3400 rpm under Mach3 control. The low end wasn't too bad as delivered but the top end was miles out.

I have now adjusted my machine following this procedure and I am now happy. Of course the calibration is for speed settings with no overrides.

Hope this helps for those who like myself wondered how to do this for 12 months.

I was lucky that my machine front panel speed display was quite accurate when checked with my laser optical tacho so I did not need to adjust this. If any one knows how to calibrate the front panel rpm readout, please let me know and I will amend the procedure below so others can benefit.

Kind Regards


Hi All,

I am having problems with Mach3 not completing the movement to the last x, y, z position requested in some G codes that I have written.  This occurs in both simulation and on my milling machine. 

It appears that if a requested Z position is reached before  a requested X position, Mach3 stops.  When the code is run for the next part, Mach3 "remembers" that it did not reach the requested X destination and completes the move that it should have done previously.  If a requested X position is reached before a requested Z position, all appears to be OK.

Below is an example of my faulty code:

(This routine spot drills 8 holes)
(CJH 26Jun07)

G00 G17 G21 G40 G49 G50 G64 G80 G90 G94
M6 T1 (TOOL Ø5 Spot Drill)
M3 S2500
G00 X8 Y14.2 Z5

(Spot Drill Routine)
N1G81 X8. Y14.2 Z-2.1 R3 F50 G99
N2 X27.5
N3 X47.5
N4 X57.5
N5 X87.5
N6 X97.5
N7 X117.5
N8 X137.

M9 M5
G00 X0 Y0 Z50
M30 (End and rewind)

It is the line "G00 X0 Y0 Z50" that X0 is never reached despite the fact that the following M30 command is reached and operates correctly.  The X position reached is always approx 29mm.

Am I missing something?



General Mach Discussion / Unspecified failure message
« on: June 18, 2007, 07:30:08 PM »
When I try to set the spindle speed with M03 S1500, I get an error in Mach3: Error on line 2 - Unspecified failure, and it presents a VB debug screen.   This does not happen consistently but when it does it is very disconcerting.

Several other users on cnc zone forum have reported this but no one seems to know the fix.  Can someone here help?

I have other issues with Mach 3 but will report them one at a time starting with this one.



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