My DSP 1060 machine calls for a proper ground connection direct to a ground rod, not a water pipe or conduit. I’ve got a ground rod in the corner for my CNC milling machine and it’s hooked up to that for now.
How important is the grounding wire length and gauge? I’ve just run 14 gauge MTW for now since that’s what I had a lot of on hand. Should I be using a heavier braided grounding wire?
Thanks,
Scott
Why wouldn’t you use the ground wire on the AC power plug for the laser?
Mine said the same thing… I just rely on the AC ground. It’s common to the chassis / grounding lug of the machine.
I think it is best practice not to have a secondary ground rod for a branch circuit from your already well grounded panel.
I’m not worried about what my Chinese machine specified. Similarly, i sure as hell didn’t trust, use, or maintain any of the wiring to those universal outlet fire traps on the machine. Lol.
The grounding post is for two-wire AC installations common in Asia.
You should have all your machines at the same ground potential - pump, air, extractor and laser. Check your chassis and all components against the centre-pin of your power plug.
You can use the ground post for ensuring your water reservoir is at the same potential.
The manual for my US-made CNC milling machine has a page and a half devoted to proper grounding, with ground rod specs and wire gauges listed, and dire warnings about voiding the warranty if it’s not independently grounded close to the machine.
TREE MACHINE TOOL CO., INC. requires a separate “ground electrode” for grounding its machine tools. Maximum Permissible ground resistance is 5 ohms. Ground rod placement should be at a point as close to the machine as possible.The machine tool should not be grounded through its own conduit.
From a quick look around online it sounds like this is pretty common, and a source of contention since you’d normally have a single ground point. If the laser doesn’t really need an independent ground, then I won’t worry about it.
And no, I don’t use any of the universal outlets on the machine. Wiring issues aside, the machine is running off a 240v transformer and the chiller wants 120v. If I could change the voltage for the chiller, I’d just run the whole setup off of 208v (still in spec for the laser) and skip the transformer, but I’ve got the cabling all run overhead and running a separate AC line for the chiller would require another hour on the ladder.
“Tree” were an industrial clearing house - their CNCs were made by Kao Ming
Not my Journeyman 325, as far as I can tell. Nameplate says it was made in Racine, Wisconsin. From what I’m seeing online maybe the later machines under the Tree name were imported, but I don’t see any sign that this was made overseas.
If your journeyman is CNC, that’s a retro-fit, isn’t it? How old is that machine - certainly older than the last two or three decades.
I guess I should have qualified that - Tree as a manufacturer is now a clearinghouse. Their current machines are made by Kao Ming.
The requirements for grounding a machine that draws quarter of an amp, are much different to those requirements for a machine drawing 10A.
Not a retrofit. It was built in 1989 with a Dynapath Delta 20 CNC. Sounds like maybe they sold off the name at some point, like Westinghouse?
as a Master electrician…
using the grounding system on house wiring is a safer way to go instead of a separate rod altogether.
you can use house ground and rod but redundant.
if there were a lighting storm and it struck ground by rod, it would energize metal frame and could cause damage.
connected to house wiring it would have much less chance of energizing frame…but still small chance
if the house wiring has a ground rod at service and the water pipes are grounded from that, you can use a pipe clamp from attic water line, hose bib or any other means to get a ground from.
there is specific size per amperage on the grounding wire. insulation does not matter
15A - 14 awg
20 - 12 awg
30A - 10 awg
electrical shorts take path of least resistance but if cannot have that path, it does and will make it’s own path being a back-feed to electronic devices or something else it can “escape” to.
electronic devices controlling machine should also utilize same grounding so there is not a ground loop causing interference in system.
also, make sure the connections have some type of anti-corrosion agent at point of contact. most likely different type of metals at terminal connections, aluminum frame and copper lug with steel bolt, has a good chance of oxidation and rust forming that would cause loss of connection eventually.
there is constant changes in our NEC code for grounding because it is always being studied and the new technology changes how thing react with grounding.
90% of intermittent problems I see are due to poor grounding of the internal components, chassis, water receptacle, through to the earth pin.
The ground pin on a laser is for countries with primitive electrics, often only two-wire, in Asian and eastern-europan open-air workshops.
Educating people that having two earths is a bad idea, is also worthwhile.
Anyone can check and remedy earthing problems with a gas-station multimeter, or even a flashlight and a couple of bits of wire.
The easiest way is to unplug your mains lead from the wall, leaving it plugged in the back.
If you’ve just been using the machine, turn it off and give it a minute to discharge itself before fiddling around. There’s very little chance of any problems, but a capacitor in a psu can give you a shock if you’re not careful, so best to wait a minute and be safe.
First check the centre pin of your power cable with the chassis. A screw or bolt is a good place to check. If you’ve got a good connection (less than 0.001 ohm/ bright flashlight bulb) then go on to check every ground on the psu’s, controllers, etc. against the chassis.
If you find a device or connector has a poor connection, undo it, clean around it and, if necessary, scrape a bit of paint away - a Dremel or similar battery tool is very handy - clean it and redo and retest.
I’ve found some machines to have many, many bad grounds. Don’t assume if you find one it’s fixed. I view it as ‘where there’s one…’
The cause of poor earths can be: the connector; the wire to connector interface; poor mechanical connection to a chassis skin; poor mechanical crimping of the connector; incorrect termination (yes, 5V - 24V through the chassis. Doesn’t really break anything, but it causes havoc, especially when intermittent.)
You need to pay particular attention to your high tension lines from the LPSU to the tube. You definitely don’t want any chance of an earth on the pre-ionisation side. Plenty of silicone and shrink-wrap. fire it up in the dark - any leakage of current will show as sparkly mini lightning. That’s bad. You can hurt yourself or your machine if HT goes to ground.