Messages

31

General Mach Discussion / Re: Limit Switches and Interference

« on: October 26, 2012, 11:05:19 PM »

Well...............my problem is worse now

After re-wiring the limit switches with shielded cable and grounding one end of the braid per separate cable run, my limit switch circuit is less reliable than ever.  On the bright side, perhaps this might make diagnosis easier.

I'll systematically try to rule out faulty switches and bad solder joints etc but after that I'll be stumped.  I'm beginning to think my CNC controller might be twiddling pins at the limit switch pin inputs - can't get a return call from the place of purchase (I deliberately purchased locally to get help if and when needed - sheesh).

Might even try configuring the Mach3 limit switch circuit as Normally Open, but that would be less than ideal even if it worked.

Suggestions welcome

32

General Mach Discussion / Re: Limit Switches and Interference

« on: October 15, 2012, 05:26:20 PM »

This may be another case where I've rushed in when I should have made another cup of coffee and had a good think about the problem.

Using unshielded single core cable and running to each limit switch in turn (i.e. a loop) probably just created a rather affective antenna to collect EMI.  Of course, if I tried to build an antenna it probably would have failed, but I'm great friends with Murphy

What I plan to do now is use 2 core shielded cable and run each back to a common point, series connect the switches at that point and take the circuit ends back to the limit input to my controller.

33

General Mach Discussion / Re: Limit Switches and Interference

« on: October 14, 2012, 09:45:44 PM »

Thanks for the replies.

I'll get some shielded cable and re-wire those limits switches.  And I might have a tinker with the debounce setting too.

Perhaps ferrite chokes would have solved my problem.  My system must be close to stable.  They would be the $6 and two minute solution.  As opposed to the re-wiring solution at $40 and four hours.

34

Tangent Corner / What's a good rust preventative to protect rails and screws?

« on: October 13, 2012, 07:27:59 AM »

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?

Thanks.

35

General Mach Discussion / Limit Switches and Interference

« on: October 13, 2012, 03:23:56 AM »

First real post on the board for me!

I'm setting up the limit switches on my CNC router at the moment.  They're just the simple lever type, two per axis, wired in series and normally closed.  Yesterday they were working so well I sat back with a coffee to admire my success while watching the LED indicator lights up as expected on the Mach3 Diagnostics tab.

But today I've had a setback    The only difference is that I also wired up the stepper motors and gave them a spin.  They worked as expected too.  But just when I thought this home made CNC caper was easy, I got an unexpected limit switch trip.  I can reproduce it, but it is random.

I'm wondering if the wiring to the limit switches should be shielded?  At the moment it's not - could that be my problem?

Thanks.

36

Mach4 General Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: October 13, 2012, 03:11:34 AM »

Hi All,

I've been lurking here for a short while now and trying to understand as much as I can.

Thanks to all those posing questions and and especially to those who have provided answers

At the moment I'm making a CNC router specifically for cutting model helicopter sideframes out of G10 epoxy fibreglass sheet.  The router is around one year in the making so far - not many of my projects proceed quickly!  I've just purchased Mach3 from Holmann Designs here in Australia.  Just waiting for the licence file to "upgrade" from the demo version of the software.

Just sorting out travel limit and home switches before tuning the stepper motors.

Shouldn't be long before trial cutting (famous last words).