I’ve looked at a bit of posts in this community and a lot of people are talking about grounding things. I’m not sure how to do it on a practical level though?
Do you have any links to posts or guides about grounding for the Shapeoko? Is it just the machine itself or is it the vacuum? Any pictures?
Edit: @gdon_2003 I have my Shapeoko in an enclosure: Designing a soundproof'ish enclosure for my new SO3. Do you think it would help to put a glass of water or something like that in there to increase the humidity? Kind of like in a humidor (cigar box)?
There is no loss in speed, but there is a limit in speed/bandwidth to which an isolator is rated. The “USB” isolators that @holgersindbaek referenced are rated for USB 2.0 so up to 12Mbps. I honestly could not tell an excellent isolator from a poor one without trying them, they all use the same basic chips (e.g. the ADUM4160), but EMI devils tend to hide in the details (of the PCB design/routing).
I am not in a position to recommend any particular one, since I never used one on my Shapeoko. I think support should be able to provide a reference though
How exactly would you ground the vacuum and the machine when you live in an apartment in Europe? I that you’d wrap a cobber wire around the vacuum, but what would you attach it to? Would you buy a Schuko plug like this - https://www.av-connection.com/?PGr=1857 - and attach it to the third leg? Maybe attach it to the radiator?
Is it necessary to plug the vacuum, router and Shapeoko into different sockets or should it be fine if I attach the vacuum and router into one socket and the Shapeoko into another?
@LiamN is the grounding GrandMaster, he will probably have good tips and know of specific plugs you can use that expose the Earth wire (I don’t have any advice to provide, since I am ashamed to say that I never bothered to ground anything on my machine, because I never had to…).
Once you have a good place to pick-up a solid ground, and since priority #1 is the dust hose, I would definitely buy some length of antistatic hose (the ones with a copper wire embedded in the hose). I bought mine off a local reseller (and then never bothered to connect the copper wire to anything…I’m that lazy)
It…depends on how the circuits are wired, everyone’s setup is different. But if you can plug just the Shapeoko in a different outlet, it won’t hurt. There is no need to try and isolate the router from the vaccum, they are not sensitive to EMI anyway (not at the levels that are a problem for high-speed/low-voltage electronics like USB…)
You can just use any plug that allows you to wire it up yourself and only use the ground pin, ignore the two power pins, this will get you the same ground that your power wiring is using, but do make sure you get the ground pin…
As Julien says, an antistatic hose is the better bet. You can’t really ground something that is not conductive, that’s how we make capacitors. The plastic in the antistatic hoses is doped with something conductive so that the charge can leak away to the reinforcing wire. This wire is then the easy place to ground the hose.
I wouldn’t do anything to the vacuum unless I had to, they’re not designed to be grounded in most cases. Ground the hose to the Shapeoko and that should ensure the CNC isn’t getting static discharge noise.
After the hose, if you still have a problem, making sure your Z axis is grounded is also a good plan, that will also ground the outer metal shell of your router without you having to mess with the router.
It is good advice is to only do enough for your specific problem to go away
What type of plug do you have that your Shapeoko is plugged into. I did some research on Danish/European electrical connections and will write up my research but I need to know what type of plug you are using:
Type C - The standard European plug. Commonly used in Europe, South-America and Asia, but also in quite a few other countries. Plugs of type E and F will also fit in a type C outlet.
Type F - Used in almost all European countries and Russia. Also known as the Schuko plug. Plugs of type C and E will also fit in a type F socket.
Type E - Mainly used in France, Belgium, Poland, Slovakia and the Czech Republic. Plug types C and F also fit in a type E outlet.
Type K - From Danish origin, mainly used in Denmark and Greenland. Plugs of type C also fit into a type K socket, and there is unsafe compatibility with plugs of type E and F.
Please reply back about which type of plug you have.
@Julien So you have a copper wire running through that hose and then the trick is to connect the copper wire (how do you do that without ruining the hose?) to another copper wire that you ground? I’ve read different things about the hoses. It seems some are with a wire and some without? Some say they work and some say they’re just junk?
@LiamN Thanks for the suggestions. I’m guessing you just connect the copper wire to the metal surface of the plug then? Problem is that I haven’t got a grounded plug near the Shapeoko (I live in an apartment). I’ve read somewhere that one can ground things to the radiator. Some say that it should be fine and some say that one absolutely shouldn’t do it. What do you think? It doesn’t seem to be that much current that’s generated, so I’m not sure what the damage could be?
From what I understand, you’d ground the vacuum hose to the Shapeoko? Which part of the Shapeoko? And then you’d ground the Shapeoko itself?
Edit 1: What do you guys say to the idea of putting a container with water in the enclosure? That should increase the humidity. Do you think that would have an effect?
Yes. You just strip the copper wire near the end of your hose (e.g. where you plug it into e.g. your cyclone dust separator), you just need a centimeter or so, so if you do that in the small length of hose that covers the cyclone intake anyway, there will be no harm to the useful part (and no air leak)
I’m sure there are fake antistatic hoses out there that won’t work, but if the description explicitly states it is antistatic, and you see the embedded copper wire, and it’s not dirt cheap, it is an indication that it’s legit. Anyway, it cannot be worse than a large length of regular non-conductive plastic hose
Does anybody have a convenient and simple way to generate static and directly it to the Shapeoko?
Reproducing things is always useful to help diagnose the issue and validate a solution. If we can generate a static discharge deliberately, we might able to find out the cause of an individual’s disconnection issues more scientifically.
I have a regular old 30’ shop vac hose attached to an Oneida Cobra Vacuum. When I first hooked it up, the hose ended up covered in fine dust, stuck on by static. I KNOW it’s not supposed to work, but I took a long piece of copper ground wire, wrapped it around the OUTSIDE of the hose (photo below), and tied it off to a gas supply line that I knew was grounded. Everyone will tell you that this won’t work…but I don’t have any more static build up on that hose. I was prepared to run the wire through the hose, and was wondering the same thing about how to get it out of the hose without damaging the hose and losing suction…but I never had to deal with it. Maybe give that a try first? It worked for me and was really easy to do.
You could certainly try just grounding the hose to a radiator yes, they are generally grounded reasonably well, although a safety inspector or a plumber might shout at you. Not much current, we’re just leaking away the static charge.
I’d just ground the hose first as it’s normally the major offender.
You could just put a humidifier in the room with it?
What’s actually going on, based on my knowledge of how humidity affects computer servers and data centers, is that when either the local relative humidity or ambient temperature is very low these conditions allow significant static charge to build up where you have moving air or dust particles.
Above is the psychrometrics page on Wikipedia.
The factor that seems to control the conductivity of the air and therefore it’s ability to leak away static charge is the absolute humidity, this is the ratio by mass of water vapor to the rest of the air.
The humidity ratio is not the ‘humidity’ they talk about on the weather forecast. The amount of water the air can hold before saturation depends on the temperature. The warmer the air the more water it can hold. At saturation rain, cloud or fog forms. Relative humidity is a measure where you are between desert dry and san-francisco summer for that air temperature.
The important bit is that the actual amount of water in the air (humidity ratio) does not change as cold outdoor air comes inside and gets warmed up. The amount of water the air can carry does increase though, so the relative humidity reduces. This is why it’s dry indoors during a cold winter, even if it’s raining outside.
Conversely, if you take air with some water vapour in it and cool it down the saturation limit reduces, the relative humidity goes up and some form of condensation forms. This is why clouds and rain work (it’s cold at altitude), why aeroplanes and other things with wings form vapour trails, why you can’t boil a kettle properly on top of a mountain etc.
So when you’re machining with your Shapeoko on a cold winter day (or on any day in Arizona) there is so little water in the air that there’s not enough conductivity in the air to bleed away the static charge so instead it builds up and zaps either you or your Shapeoko.
And which points out that you want to override that organic process with one that is purely mechanical and reliable … copper wire. Provide a low resistance path so the static electrical field won’t build up in the first place, and will be continuously discharged.
Back when I designed instruments for HP, we had a static discharge tester that was basically a capacitor tied to a metal screw on the end of a non-conducting handle. Don’t know if these are easily available; I think we made ours. You could vary the voltage, capacitance and ESR to test to different models (human body M/F, assembly machine, packaging machine, etc.). The voltage involved in these devices is not to be trifled with; occasionally the thing would discharge back through the handle and this usually resulted in it being thrown about the room.
I was more looking at why some people have an issue and others don’t, or only occasionally have an issue.
With regard to discharging the static, you can only discharge it from areas that you have conductivity to. There will still be static on the workpiece and chips and on any other parts which come into contact with these, unless they are conductive and have a path to ground. So you’re still likely to see chips clogging in the cut in plastics as there’s no discharge path once the cutter has moved on down the cut.
