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Topics - brw0513

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General Mach Discussion / My VFD Drive Controls My Stepper Motors
« on: May 15, 2014, 05:29:07 AM »
I'm a patient man and my glass is always half full, but my CNC router sure is testing my resolve   :-\  

I'm having nuisance limit switch triggers and have decided to use the second parallel port (PCI slot) on my PC to double the number of inputs available to Mach3.  The idea was to use these additional inputs to help identify if there was a pattern to which limit switch is supposed to be getting triggered.

To test the parallel port, I just enabled the port and changed the port settings within Mach3 (via ports and pins) and swapped the printer cable over.  Things were going great until I turned on my spindle (Teknomotor driven by a Delta VFD, speed set manually via a dial on the VFD).  When the speed dial was turned Mach3 registered an immediate emergency stop but even so the speed dial on the VFD controlled my stepper motors     ???

Anyone had this before?

Can anyone offer any things to try to solve this issue?


General Mach Discussion / Suggestions for Commissioning My Router
« on: April 21, 2014, 12:17:03 AM »
I've nearly finished my CNC router  ;D  It's a moving table design using NEMA23 steppers, Teknomotor spindle, an Australian made PROMiCA IC3A controller set to 1/8 micro-stepping and Mach3 software.  I'm very happy with how it turned out.

The NEMA23 motors are 1.8 degrees per step.  With 8 micro-steps per full motor step, a 2:1 gear reduction to 5mm pitch X & Y lead screws then I have 640 micro-steps per mm of travel.  There is no reduction on the Z axis so its 320 micro-steps per mm of travel.

Is there any recommendations for commissioning?  So far I've tried three things:

1.  I've plotted out a relatively simple geometric pattern (circle, rectangle, square) on paper.  With the plot on my router table and a USB micrscope fixed to the spindle case I've written basic G-Code to chase the plotted path.  It worked well enough, but I think the plotter introduces a slight scaling to distort the plotted size.  I'd only rate this strategy as 7 out of 10.

2.  I've laid a scale rule on the table and used it compare linear moves requested in simple G-Code.  This worked very well.  I'd rate this 10 out of 10 but it only assesses one axis movement at a time.

3.  I've run the "road runner" G-Code file that comes with Mach3.  The image shown by the USB microscope never comes back to the (0,0) centre pop mark - it's sometimes off by around 0.25mm but once it was off by around 1mm.

Cutting a template out of MDF is the next thing on my list, I'm interested to know what others have chosen to do. 

General Mach Discussion / Soft Limits Not Working
« on: February 12, 2013, 02:13:23 AM »
Still learning and enjoying the process  :)  Although I hope this is not a dumb question  ???

I've set up the Soft Max and Soft Min limits under Config/Homing/Limits.  But Mach3 lets me drive (via system hotkeys) right past them.  Is there some other step required to enable the soft limits I've set?


General Mach Discussion / Finding Hole Co-ordinates - Is it a Macro I Need?
« on: February 08, 2013, 09:16:57 PM »
I have a model helicopter sideframe made out of 2mm carbon fibre sheet that I'd like to duplicate, at least in part, in epoxy fibreglass sheet with my router.  The sideframe has a goodly number of 3mm holes that need to be known with reasonable accuracy.

I have a USB camera mounted in the router spindle, and via the Mach3 video window, the 3mm hole centres are easy to see and it won't be too hard to accurately hover over the hole centre.

What I'd really like to do is just hit a key on my PC keyboard and have the X & Y co-ordinates logged to a file for later processing using MS Excel.  If my memory serves, I've seen a thread some time ago that included a macro that did this - but I can't find it now.

Any help appreciated.


General Mach Discussion / Commissioning Tests for CNC Router
« on: January 17, 2013, 09:53:12 PM »
It won't be long now and I'll be performing some test cuts on my router.

Just wondering if there are any recognised test shapes that people use to test accuracy of setup?

I was thinking about cutting some circular pieces out of a piece of PVC sheet.  When tool offests are changed about, one piece could be the plug and its quality of fit in the intended matching hole would give an idea of dimensional accuracy.

What have others here done?

General Mach Discussion / Fluorescent Lights and Interference
« on: November 22, 2012, 06:32:35 AM »
Just wondering if fluorescent lights could cause interference with limit switches and home switches.

Earlier tonight I was trying to solve some odd behaviour with the Z axis home switch (photo interrupter type) on my router.  The slit in the switch faces up so one possibility was the collector was seeing the light from the flouro, either directly or reflected off the blanking blade.  To test the theory I turned the lights off  ::)  To my surprise the home switch behaved itself.  When I turned the lights back on, my stepper motors seem to re-energise - they certainly rattle with the flouro as it blinks on.

My router is in a small garden shed.  The headroom is so low the double flouro battens are just above head height.  Realistically, I couldn't get then closer to the router if I tried.

Anyone got an opinion?

A new shed is on the cards when funds allow.  LED lighting?

General Mach Discussion / Z Axis Home Switch - Odd Behaviour
« on: November 20, 2012, 10:13:27 PM »
My Z axis home switch is now performing rather oddly  ???   Grrrrrr.

When I "Ref All" the Z carriage retreats to the Home Switch and is recognised by Mach3 but it doesn't back off the switch position i.e. the yellow Motor 3 home LED remains lit on the Diagnostics tab.  The Y and Z axes sequence as expected and each of these back of their switch positions i.e. in turn the yellow LEDs light up then go out.

Why doesn't my Z axis back off?

Absolutley no changes made to the router. 

Ay suggestions appreciated.

General Mach Discussion / Could Windows XP be Twiddling the PP Pins
« on: November 07, 2012, 05:13:23 PM »
I've had no success in trying to solve my nuisance limit switch tripping.

I'm at the point of clutching at straws now.

Is it possible Windows XP is twiddling the parallel port pins?

Any tips for me?


General Mach Discussion / Stepper Motor Cables - Shielded or Not?
« on: October 30, 2012, 06:53:44 AM »
I started a previous thread about limit switches and interference - still haven't solved that one, but when I do I'll update with what I've found.

My questions now are:

1.  Do you use shielded or unshielded cable to supply your stepper motors?
2.  If shielded, where do you ground your shields?

IIRC, I have seen a few cnc hardware suppliers that sell 4 core unshielded cable, pressumably for stepper motors.  And from my current experience :) if I used unshielded stepper motor cable, then I may be blissfully unaware of my likely earth loop problem.


Ian B

Hi All.

I've been using Inox MX3 to spray the ground rails and ball screws of my CNC router to prevent rust and provide lubrication.

My CNC router is in my garden shed since I just don't have a proper man cave  ::)  It gets hot in there to the point the Inox seems to flash off - what's left behind feels dry and even a little sticky.  No rust  :)  but no longer term lube either  :-[

Can anyone recommend a good rust preventative that will hang around in my application?


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