[Alectro]

Hello everyone,

over the last two month i built a DIY cnc with alu profiles, Nema 17 step motors, 12 volt(20A) power supply and a cnc shield attached to an arduino. I use a desktop pc. As software I use estlcam and everything works fine so far. Now I've bought a 500 watt Dc spindle from china as depicted on the fotos. I use a different power supply for the spindle as well as another power socket for the spindle.

Now my problem: When i start the spindle the arduino feezes or resets, however the software estlcam shows different alarm messages sometimes "no connection" or "com3 usb failed" or just "cnc controll stopped".

I read multiple posts according to interference but most of them points at the big AC spindle with VFDs.I also know that USB 2.0 is vulnerable to EM fields but when i used a dremel as spindle there were interferences.

Therefore my question is, if anyone had the same problems and if there is a simple solution due to the fact that this spindle is sold 1000times and there must be others with this problem.

Thanks in advance,

Alectro

[grg12]

First photo suggest that power cables of spindle are far away from any other cables - thats good. What i don't like - spindle uses single lead cables and they are far from each other creating large "loop" - bind both cables together or - even better - twist together (create "twisted pair" ). Check if spindle has EMI suppression capacitor - without it DC motor will generate a lot of noise. Check if there is electrical connection between spindle power and machine chassis (baaad thing).
No guarantee it will help - these problems can be tricky to solve.

[Alectro]

Hey thanks for the reply, the twisting of the cable between power and spindle did help actually!Sometimes it still happens but now the arduino doesnt freeze for minutes!!The spindle doesnt have any capacitor!There is no connection between cnc chassis and spindle, though i saw a lot of functioning cncs where there is metal contact between both. What capacitor should I use?i mean Ican google that but if you have the same spindle I would try the work fine one

[grg12]

I don't have this type of spindle - i don't know what supply voltage it uses or how to calculate correct condensator value. If there is no recommended condensator type for this spindle - i would just look for foil cpacitors rated for 3 (or more) times supply voltage in 0.1-1uF capacity range and try. If you find spare emi suppression ferrit cores ("bulges" on computer power cables) - these are also worth trying.

[hfjbuis]

Make sure all earth wires are thick and connected to a single point (star connection). To connect on a metal frame, use toothed washers.
I see all cables including the logic signals from limit switches are bundled together. Absolutely separate the low voltage arduino signal cables from the stepper and supply cables.
Use a single wall outlet connected to a single junction box to power your devices.

[Alectro]

Hey hfjbuis i did the star grounding but i didnt earth the metal frame just the spindle chassis. The end stops are all NO( normally open). I put a ferrit bead around the USB cable and now everything WORKS FINE!Before that i tried a capacitor at the spindle between the terminals but due to a PWM control it just flipped on and off^^ what makes sense in the end. probably there are special capacitors or circuits for that but i dont want to play with over 100 volt that come out of the PSU. It is still amazing how other solved this because there is not very much information in various forums about this specific problem!Most of them deals with VFDs ergo AC motors not with 500 watt dc motors with PWM control. Besides i measured up to 20 volt in the metal frame before twisting the cable and grounding the spindle. You would not be allowed to sell such devices in EU or just with big signs of EM Noise
However thanks all for the support!

[hfjbuis]

i did the star grounding but i didn't earth the metal frame

An earth on the metal frame is not just a EMI protector, but also a safety for those high voltages you are working with. But watch out, if you use the metal base as GND, to save a wire, you could blowup the electronic's attached to that wire due to ground loops. Especially those devices that serve as a reference point for the mill in the spindle, often have no separate GND wire.

Anyway have fun and be safe!