[feragto]

Hi , I conected today my first home made CNC router . But in phase of testing I notice that my home-limit switches on set-diagnostic screen of MACH 3 very quickly turn on and turn of , not regulary ant not in some kind of order . I assume this is a electric noise ?! I try all disconected ald connected but without succes . Programimg part is not a problem , I do all what I need in MACH 3 . Can somebody help me with a few suggestions ?
Thanks .

[Dorsal]

Are you using shielded wires for those home and limit switches? Is the shield connected to ground at the controller card end only?

[johnmac]

Go to the general config page and change the entry for the debounce. Since you can see the switches tripping, you may need a setting of 7000 - 9000.

John

[Realmseeker]

I have the same problem sometimes as the first poster. I tried setting debounce to 1000-2000. The problem I have is that if I set it any higher, after my limit switches make contact when homing, my gantry moves way off the limit.

I to do not have shielded wiring for my limit switches, and most likely really need to consider the upgrade. I have a small problem that during a program run, my machine gets a false positive on the limit switches. But this only happens if I have my spindle running, and not during a test cut when just cutting air.

[JD_Mortal]

I am not sure what you are using for your switch, but I can list a couple of things that may be wrong...

If this is a physical switch connection, there is no such thing as "noise" in an open-wire connection. However, if you are plugging this into a "circuit IC" to detect open/close state, and you have poor grounding, and the IC is RF sensitive... You have a ground-loop issue. Check your grounds and shielding, and any noisy-RF device that is too close to your detection circuits.

If your switch is cheap, it may have poor spring-tension keeping the switch open/closed. Switches have g-force ratings, get a switch with better g-force ratings to stop from being physically vibrated on-off.

If your switch has micro-contacts, with a micro-gap, but your switch-voltage is too high... It is arcing, or the plates are becoming a mini-capacitor and releasing built-up electrons once it fills or vibrates a micron closer.

Try a physical debounce on the switch... Though, it is not a debounce issue. (A high-ohm resistor 5M and a 0.001uF capacitor. Should keep a slight low voltage, and absorb high RF noise, keeping a low-state presence. As opposed to being an open-IC path which senses cross-talk from the chip and RF noise in the line. Going from 0v to 5v is not what an IC expects, it expects ~<1.5v low to ~5.0v high, for example.)

Try an RF choke and shielded wires. (Shielding must be hooked-up to ground, otherwise it is just more capacitance and RF antenna structures.)

Get a new LPT port/cable/computer. LPT chips, and older computers are horrible. They self-collapse and become electrical "ghosts in the machine", which is why everyone abandoned old computers and LPT ports in the first place.

[Fastest1]

Get a new LPT port/cable/computer. LPT chips, and older computers are horrible. They self-collapse and become electrical "ghosts in the machine", which is why everyone abandoned old computers and LPT ports in the first place.

Not all of us have issues with the PP's. Nor has EVERYONE abandoned them. Maybe the big machine shops dont use them anymore but the home shops are alive and well on PP computers. He also states the diagnostics page is showing a light flickering whether the limits are connected or not. Does it flicker if you disable the limit switches? I know it shouldnt but you have to exhaust all possibilities. Is the machine or its frame physically touching the controller and or computer or its case?

[feragto]

Not all of us have issues with the PP's. Nor has EVERYONE abandoned them. Maybe the big machine shops dont use them anymore but the home shops are alive and well on PP computers. He also states the diagnostics page is showing a light flickering whether the limits are connected or not. Does it flicker if you disable the limit switches? I know it shouldnt but you have to exhaust all possibilities. Is the machine or its frame physically touching the controller and or computer or its case?

Yes , the light go on and also disable electronic (same as I press the switch) . No , there is not any contacts between machine and electronic case or computer . I have electronic from CNC Stepper Motor Driver Systems & Hobby CNC Routers:: PROBOTIX™ .

[hemsworthlad]

This is very common and easily fixed by doing what Johnmac suggested and setting the debounce in mach or if real bad then using a small capacitor.

Usually the debounce will solve the issue straight away and i think it will in your case as well.

There wont be anything wrong with your PP or computer so ignore JDMortals biased comment over PP's he's obviously wrong because just about every DIY CNC ever built use's the PP (Except me I use Smooth stepper, but for other reasons.!)

Good luck.

[feragto]

This is very common and easily fixed by doing what Johnmac suggested and setting the debounce in mach or if real bad then using a small capacitor.

Usually the debounce will solve the issue straight away and i think it will in your case as well.

There wont be anything wrong with your PP or computer so ignore JDMortals biased comment over PP's he's obviously wrong because just about every DIY CNC ever built use's the PP (Except me I use Smooth stepper, but for other reasons.!)

Good luck.

Can you point me in direction to mount a small capacitor ("normal" or "electrolitic +,- ") , how big ...nF , uF ..., and where to mount . Thanks in advance for your help .

[feragto]

Hi ,
I am notice that my debounce interval and index debounce is booth zero (o) . Because I have electric dust in my home- limit switches , can somebody help me and tell which value need a write instead of zero , mybe this will solve my problem . My MACH 3 running on 35.000 Hz.
Thank you in advance for help .

[brtech]

try 1000 first. You can go up to 7 or 8,000 if you need to.

For a capacitor, I think .1ufd would be adequate.

[feragto]

try 1000 first. You can go up to 7 or 8,000 if you need to.

For a capacitor, I think .1ufd would be adequate.

I this value the same for booth debounse and index , or only for debounse and the indes value is zero ? Capacitor wired series or paralel ?

[brtech]

debounce, parallel (across the switch)

[Al_The_Man]

Programimg part is not a problem , I do all what I need in MACH 3 . Can somebody help me with a few suggestions ?
Thanks .

Have you actually carried out industry standard recommended Earth Grounding, Shielding and Bonding recommendations on the system?
I have found most 'noise' problems are caused by the lack of this.
The urge to get a system up and running, usually results in recommended practice going by the wayside.

Is the machine or its frame physically touching the controller and or computer or its case?

The PC is at ground potential anyway VIA the PC. P.S. which is normally common with the earth ground conductor.
The Machine frame should be bonded to earth ground also, when proper bonding is carried out, ground loops are prevented.
Al.

[brtech]

Amen brother.

[JD_Mortal]

Not all of us have issues with the PP's. Nor has EVERYONE abandoned them. Maybe the big machine shops don't use them anymore but the home shops are alive and well on PP computers. He also states the diagnostics page is showing a light flickering whether the limits are connected or not. Does it flicker if you disable the limit switches? I know it shouldn't but you have to exhaust all possibilities. Is the machine or its frame physically touching the controller and or computer or its case?

The industry has abandoned them, not users. Would you also say that 8-tracks have not been abandoned, because some people still use them? Sorry, they have been abandoned too. (You will have a difficult time finding a new computer that is still manufactured with a PP, unless it is a custom computer for devices which still need a PP. You have to buy an expansion-card, which is just as difficult to find, for the new computer expansion slots. I use $2.00 disposable USB-PP, which is a crutch to my PC. That is like using a garden-hose nozzle on an oil-well pump.)

Back on topic...

Exactly, it occurs with or without connections, which indicates either IC component failure or decay. (Resulting in self-triggering and cross-talk voltage.) Using the program debounce setting to "fix" it, is a band-aide hack. That doesn't resolve the issue, it only hides it, at the sacrifice of switch-accuracy, which will now be off by a random amount. (Software debounce is not based off contact time, it is set at intervals. But that is beyond the scope of this post.)

[Fastest1]

Can you point me in direction to mount a small capacitor ("normal" or "electrolitic +,- ") , how big ...nF , uF ..., and where to mount . Thanks in advance for your help .

You will install the cap on the same connections as your switches, 1 pin of the capacitor will go to ground and the other pin of the capacitor will go to whatever pin you have assigned for the limit switches on your breakout board. It just bridges the 2 connections. Do you have sheilded wiring? If not, how close is the wire physically to the stepper wiring? Try seperating it as far as possible. Also in regards to setting debounce, the larger the number value the longer the signal has to be triggered to be seen. The machine will move farther onto the switch. I would suggest running slower speeds til configured correctly and try reducing the debounce to the lowest setting it will tolerate.

[johnmac]

As recommended in other posts here on cnczone, use a 0.1 mfd film type capacitor, not electrolytic.

The source of my interference is from my Gecko 251s. My stepper cables are properly shielded and grounded. It would cause random flicker of the LEDs on the diagnostics page in Mach. The capacitor will reduce or eliminate the need for a debounce setting. I needed a debounce setting around 9000 to fix mine.

I found the band-aid fix (debounce) while watching one of the Mach video tutorials. From what I have found out, many people are using that band-aid.

I also found that Mach does not support a USB to PP adaptor, found in the system requirements.

John

[Realmseeker]

You will install the cap on the same connections as your switches, 1 pin of the capacitor will go to ground and the other pin of the capacitor will go to whatever pin you have assigned for the limit switches on your breakout board. It just bridges the 2 connections.

Sorry really simple and stupid question, not an electronics guy. When you say ground, do you mean the wire coming off my limit switch, or my bundle of grounds(earth?) inside my enclosure. I am guessing you mean the wire, because if I connected my capacitor to between the limit switch and my earth ground, wouldn't that electrify my enclosure every time the switch gets tripped?

Sorry simple but I don't want to fry anything.

[brtech]

Put the cap between the input pin and power supply negative pin on your BOB