How electronic noise can perturb cnc?

[mauribastidas]

I know what noise is and how it can distort some electronic signals but in which way it affects the right performance of a CNC machine?
Looking for some drivers for my project I found out a lot of stock, some of them are really expensive; some others are really cheap but with the same power. It´s a mere question of brands or the most expensive drivers are more accurate and reliable than the cheaper ones?
What about Geckos, they look like the top-notch of drivers and they are not really expensive, the problem is that I want to get the complete kits and I understand that they don’t sell complete kits.
Thanks!!!

[acondit]

Several places sell kits with Geckos. CandCNC and Keiling to name a couple.

Alan

[mauribastidas]

Originally Posted by acondit Several places sell kits with Geckos. CandCNC and Keiling to name a couple. Alan

You are right, but anyway what to buy a Gecko? why is it considered the best driver, I've heard that they eliminate noise, but what does it mean? thanks

[Fastest1]

Originally Posted by mauribastidas You are right, but anyway what to buy a Gecko? why is it considered the best driver, I've heard that they eliminate noise, but what does it mean? thanks

I dont believe they eliminate noise (I could be wrong), however they do protect your computer with optoisolation. The G540 includes the breakout board and 4 drivers in 1 case. Connections are very straight forward and well marked. A very well built product with many happy users. With proper use of sheilded wiring and grounding, noise should be a non issue.

[JD_Mortal]

There are many forms of noise... and sources, related to CNC...

Harmonic RF noise from servo/stepper motors and driver-chips/FET's in operation. (Easily subdued with capacitors and RF ferrite coils and ferrite blocks.)

EMF noise from power-supplies and driver-chips/FET's at all times. (Not so easily subdued with with shielding of aluminum/lead/iron/steel and adequate grounds.)

ESD noise from motor brushes in some spindles and some servo motors. (Impossible to subdue, needs physical distance between the source of noise and the sensitive circuits.)

Additionally, any length of wire, unshielded and shielded, will also pick-up RF noise from AM/FM/WiFi/UHF/VHF/CB/Cell and any other wireless device near you. (That may be easy or impossible to block, as FCC states, "This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.")

Eg, All electrical devices must be susceptible to government-controlled "RF/ESD/EMF jamming devices." Yet they must not act as an RF/ESD/EMF jamming device. As is also, usually, unavoidable anyways. (You need a special license, as medical and government devices have, to be "truly shielded". Though, nothing is legally stopping you from using or creating shielding for personal use. You just won't find any devices with "stock shielding" for sale at a consumer level, which function beyond that FCC ruling. It also meens that the device should still be able to function, within a tollerable level of certain RF/ESD/EMF, without causing harm to the user. But the law is more for the prior statement. Nothing is truly "immune" to those signals, and nothing is truly "accepting" of any interference.)

The result of noise, can be anything from complete failure of operation, to undesired operation, to nothing... You don't want the device to become autonomous because your neighbor decides to use his RC airplane or cordless phone. Which is also why the law states that these devices must have emergency stop buttons that disengage the device at a physical level, not at a programming level.

Most common issues from noise...
- Missing steps
- Gaining steps
- Autonomous undesired motion
- Inability to move
- Direction bounce (When the direction signal gets excessive noise, moving forward/backward real fast.)
- False triggered stops
- Communication failure or hesitation
- Chip failure

[brtech]

I recommend the kit from cncrouterparts if the motor is the right power level for you.

The G540 is a great product: it has all you need in one very small package that can really take quite a bit of punishment. It's about as close to "plug and play" as you can get.

Since a lot of us have it, you can get a lot of support, both from gecko and from the zone.

One really good reason to get the cncrouterparts kit is the cables. They are very high quality, and have all the right shielding. You were worried about noise, and these cables will help a lot.

You do have to wire your limit/home switches, and you need to use shielded wire for that, grounded at one point, probably on the gecko side, connected to earth ground well.

Grounding is the most important thing you can do to eliminate noise. One convenient thing to do is put a 1/4-20 bolt sticking up from wherever you are mounting your gecko and power supply. Run all the grounds to ring terminals on that stud. Include the green wire ground to the power cord, the power supply, the gecko case, and the shields from the home/limit switches. If you are mounting everything in a metal case, the bolt should firmly contact the case.

[mauribastidas]

Thanks for all your answers, you help me a lot.

[mauribastidas]

Originally Posted by JD_Mortal There are many forms of noise... and sources, related to CNC... Harmonic RF noise from servo/stepper motors and driver-chips/FET's in operation. (Easily subdued with capacitors and RF ferrite coils and ferrite blocks.) EMF noise from power-supplies and driver-chips/FET's at all times. (Not so easily subdued with with shielding of aluminum/lead/iron/steel and adequate grounds.) ESD noise from motor brushes in some spindles and some servo motors. (Impossible to subdue, needs physical distance between the source of noise and the sensitive circuits.) Additionally, any length of wire, unshielded and shielded, will also pick-up RF noise from AM/FM/WiFi/UHF/VHF/CB/Cell and any other wireless device near you. (That may be easy or impossible to block, as FCC states, "This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.") Eg, All electrical devices must be susceptible to government-controlled "RF/ESD/EMF jamming devices." Yet they must not act as an RF/ESD/EMF jamming device. As is also, usually, unavoidable anyways. (You need a special license, as medical and government devices have, to be "truly shielded". Though, nothing is legally stopping you from using or creating shielding for personal use. You just won't find any devices with "stock shielding" for sale at a consumer level, which function beyond that FCC ruling. It also meens that the device should still be able to function, within a tollerable level of certain RF/ESD/EMF, without causing harm to the user. But the law is more for the prior statement. Nothing is truly "immune" to those signals, and nothing is truly "accepting" of any interference.) The result of noise, can be anything from complete failure of operation, to undesired operation, to nothing... You don't want the device to become autonomous because your neighbor decides to use his RC airplane or cordless phone. Which is also why the law states that these devices must have emergency stop buttons that disengage the device at a physical level, not at a programming level. Most common issues from noise... - Missing steps - Gaining steps - Autonomous undesired motion - Inability to move - Direction bounce (When the direction signal gets excessive noise, moving forward/backward real fast.) - False triggered stops - Communication failure or hesitation - Chip failure

JD Mortal thanks for your help, you cleared a lot of doubts I had about the issue.