static causing communication problems...again

[bking1836]

Hi everyone,

Last winter, my first with the ShopBot, I went ten rounds with static electricity from my dust collector and eventually won. I followed all of Brady and Gary's advice about running bare copper wire through the hose and attaching it to metal ductwork with a sheet metal screw. The DC itself is ground to a ground rod driven 6ft into the concrete, and I soak the ground rod hole/opening with water to improve conductivity (per electrician's advice) before running the ShopBot. My DC hose is attached to the Z car by a standoff made of plywood, rigid foam and zip ties so that the hose doesn't contact the spindle or the YZ car or gantry at all. All of this worked well last winter even on crazy cold days with extremely low humidity. The only time the problem resurfaced was the day I didn't realize my bare copper wire had come loose and wandered way up the hose, such that the static had nowhere to travel. Fixed that, and back to no problems.

Until this week. Ahhhhhhh! Nothing has changed in my setup. Today I even dumped 2+ gallons of water down the ground rod hole. I ran tests air cutting with and without the DC on, and cutting wood with and without the DC on. I can confirm with 99% confidence that the stuttering/loss of position happens only when the DC is running. Sometimes the loss of position is so obvious that I hit the emergency stop before ruining something. Sometimes the machine stutters, but the loss of position was actually imperceptible until you, for example, get to the cutout toolpath and find out that you lost EXACTLY -.125" in X at some point during the cut, which you can see clearly here:

32136

Here's video of the subtle stuttering (versus obvious catastrophic position loss):


https://youtu.be/b0GH2_MJR-s

I am at a loss. In case it matters, here are some additional thoughts/data points:

- This is happening MUCH earlier than last year, when the problem surfaced in January.

- The only new things in my shop are some LED lights and a newer version of an Apple Watch.

- I wondered if a neighboring shop was emitting something that was causing the problem, but that doesn't make sense if it happens only when running the DC

Of course this is happening right when I am ramping up again with many projects and deadlines (I am not a hobbyist).

Any help would be much appreciated!! Thanks.
Brian

[srwtlc]

It's gotta be the Apple watch, as that one has never been blamed before! Check your neighbors wrist, I bet he has one too.

Obviously I'm being facetious, but the sad sad year after year saga continues.....

Sounds like the conductor in the hose is grounded well, but how about the carriages?

[bking1836]

It's gotta be the Apple watch, as that one has never been blamed before! Check your neighbors wrist, I bet he has one too.

Obviously I'm being facetious, but the sad sad year after year saga continues.....

Sounds like the conductor in the hose is grounded well, but how about the carriages?

It's always good to blame Apple :D

What do you mean by carriages?

[srwtlc]

Well, it sounded like your hose and it's ground connection are insulated from the machine with the plywood standoff and while I don't, some people need to have each carriage (Z car, gantry, and then frame) grounded to the same common ground as well.

[coryatjohn]

I agree. Ground EVERYTHING that moves to the same grounding rod. That includes the X axis, Y and Z cars individually. Ground the DC to the machine. Ground the electrical outlets to the rod. Everything should be grounded to a common point. Be sure to use at least 10 gauge wire and bolts (I soldered lugs to the grounding wires and bolted them to the machine) to secure the grounding wires. You cannot be too anal about grounding.

[JimmyD]

You've checked all the obvious, not it's time to check the unobvious. I've worked for 35+ years in the aerospace industry, much of it designing/manufacturing missiles and bombs. We take static electricity and grounding very seriously, it's not just comm problems or missed steps, it's someones life when it static happens where it shouldn't. That being said, I recommend three things.

First is, I think you and your electrician are very mis-informed about grounding rods. It sounds like you have more than one rod in your overall system. Is your machine electrical grounded via your building electrical system? Do you have a completely separate grounding rod just for your dust collection? If yes, that's a big problem. You have created electrical potential between the two grounds which can can all kinds of issues. Just use your the ground that your machine is electrically connected to. That way the operating computer, the control box, the machine structure, the router or spindle and the dust collector are all connected to same ground with the same potential.

Second, pouring water on the ground rod is ill-informed. The soil has minerals in it, the water that you're adding either has minerals and chlorine or salt and chlorine in it. You are causing the soil to leach minerals towards and onto the grounding rod. Think how electrical plating or chroming works. Once enough minerals have attached themselves to the rod conductivity to the soil is significantly reduced. Depending on your soil this can happen quickly or slowly over time. Copper does not rust but I'm sure you have seen it "patina", that is simply chemicals and minerals changing the surface structure of the copper and making it less conductive.

Third, you may think that everything is connected and grounded, but you need to actually test it for conductivity. Use a DVM (digital volt meter) and check for continuity between all the components of your system (building electrical ground, computer, control box, machine frame, machine gantry, dust collection hose or piping, and dust collector).

Hope some of this helps.

Jim

[carlcnc]

Brian
I do not run shopbot control,but,
with what I do use when I had comm errors I found grounding the frame of the machine to the building ground fixed it.
Theory is noise [" dirtypower"] introduced by the incoming ac.
In one case it was single 18ga wire to the conduit,
in another we used same 18 ga wire to the ground pin of a 120v plug and plugged that into a wall outlet. both solved the problem
one machine was in an industrial area with a foundry across the street.
every time they fired up those big induction furnaces ,we would have issues .
Carl

[Burkhardt]

If you have a control PC with a grounded power supply (i.e. all desktops and some laptops), disconnect the power ground from the plug and connect it to the machine controller board ground as close/parallel to the USB cable as possible. Otherwise you will have a ground loop that goes through the USB cable which is obviously not good. Many newer laptops have only 2-prong plugs without ground and do not have this problem.

[dlcw]

I agree. Ground EVERYTHING that moves to the same grounding rod. That includes the X axis, Y and Z cars individually. Ground the DC to the machine. Ground the electrical outlets to the rod. Everything should be grounded to a common point. Be sure to use at least 10 gauge wire and bolts (I soldered lugs to the grounding wires and bolted them to the machine) to secure the grounding wires. You cannot be too anal about grounding.

Make sure when you bolt ground wires to the machine, you scrape any paint under the wire lug to make sure you get a GOOD metal to metal contact.

[Ken Sully]

I agree with Jim.
I you have two different grounds you will end up with dissimelar grounds and current can flow between them. Make suer your system is tied to the same ground. Not one from the house and one from your ground rod.

[bking1836]

I agree with Jim.
I you have two different grounds you will end up with dissimelar grounds and current can flow between them. Make suer your system is tied to the same ground. Not one from the house and one from your ground rod.

Well this is all pretty overwhelming, particularly for someone who knows diddly about electricity.

The only ground rod I am aware of in my shop is the one the electrician drove into the ground through the concrete. Isn't everything else grounded via the third prong of a plug right into the electrical system of the building?

Isn't the ShopBot grounded simply by being plugged into its 220 outlet? I don't have any additional copper wires going from the machine to a ground. Never have.

If I disconnect the copper ground wire that currently runs from the DC frame to the ground rod, how do I ground the DC? (It's an Oneida Gorilla Pro, and it came with a ground wire that runs from the top of the motor and clips to the metal mesh frame around the filter, which has always been attached). Run a copper wire from the metal ductwork to electrical conduit on the ceiling?

The DC is literally a few feet from the ShopBot. Does that make the problem worse?

[coryatjohn]

The problem with grounding and static is that static is extremely high voltage with very little amperage. It's very easy for electrons to leak all over the place and when they leak into the electronics of the controller, it gets messed up. The controller voltages are very low and that contributes to the problem. If you've ever worked on an old car with electrical problems, you have an idea of the importance of proper grounding.

It may not be directly intuitive but having grounds in different places can actually cause problems. That's why you need to ground EVERYTHING to that rod the electrician installed. Otherwise, electrons can flow in unusual paths and end up in your Shopbot controller electronics. Electricity always seeks the easiest path to ground and if that's through your controller, then you get problems. Provide easy paths for those stray electrons. Ground everything carefully to that rod. Take the time to run individual lines to every moving part. You should be able to zap your machine anywhere with 40,000 volts and not have anything unusual happen. The only way to do that is to be positive about your grounding.

I also agree with the others who have discussed ONE GROUNDING POINT.

[bobmoore]

now I am confused. If he has his normal electrical ground for everything plugged in and a ground rod isn't that multiple grounds for him?

[bking1836]

I wonder if the desire to help is causing people to solve problems that I am not having. The machine stuttering/loss of positioning problem happens ONLY when the DC is running -- and particularly with larger diameter bits making more chips. This leads to me to conclude that the DC is creating enough static to interfere with normal CNC operation. Which means that somehow I need to change/improve the grounding for the DC, right? Why would I need to ground, for example, the YZ car if it's the DC that's causing me problems? Admittedly I know little about this topic....just trying to be as analytical as possible.

[Burkhardt]

now I am confused. If he has his normal electrical ground for everything plugged in and a ground rod isn't that multiple grounds for him?

That was my point....If you have the control PC grounded through the 120V plug and the machine power grounded through the 240V plug (or fixed wiring) and additionally the machine frame itself through a ground rod that sounds like trouble.

[jTr]

The only ground rod I am aware of in my shop is the one the electrician drove into the ground through the concrete.
Good. This is THE sole ground for your building. It should be connected directly to your breaker box, which in turn is the ground reaching to your outlets and any metal conduit running from the breaker box.
(In other words, there is no ground coming to your building via the power lines) All things grounded eventually lead back to this single grounding point.



Isn't everything else grounded via the third prong of a plug right into the electrical system of the building?
The third prong of that outlet is grounded, but only because it's path eventually leads back to that grounding rod. Again, there is no ground fed to your building through the power lines.


Isn't the ShopBot grounded simply by being plugged into its 220 outlet?
Not entirely. The shopBot control box is grounded by doing so, but not it's metal frame.




I don't have any additional copper wires going from the machine to a ground. Never have.
I'd call this a bingo.
It is imperative that a ground wire be run from the metal frame. Typically done near one of the feet, an un-insulated cable clamp is fastened to your machine, being careful to scrape away paint to establish a metal to metal contact. Better yet, drill a hole in the frame and use a self-tapping screw to attach. Clamp a relatively heavy gauge ground wire to it, and connect to ground. In my case, it is attached to metal conduit, which is attached to main breaker box housing, which as you may recall from above, goes to the main building ground, in your case, the grounding rod.


If I disconnect the copper ground wire that currently runs from the DC frame to the ground rod, how do I ground the DC? (It's an Oneida Gorilla Pro, and it came with a ground wire that runs from the top of the motor and clips to the metal mesh frame around the filter, which has always been attached). Run a copper wire from the metal ductwork to electrical conduit on the ceiling?


Not sure why a line goes straight to the rod - if it's plugged into a grounded outlet like any other machines in your shop, should be good.
Either way,you don't want to disconnect it.

HOWEVER: you must not let that DC hose ground make contact with any metal on the cnc framework (which by now should be grounded) or you'll make a ground loop, which would generate it's own set of problems.



I sympathize, as I've been there with the comm's issue. Keep us posted, as we want to see you running smoothly.

Jeff

[bking1836]

Good. This is THE sole ground for your building. It should be connected directly to your breaker box, which in turn is the ground reaching to your outlets and any metal conduit running from the breaker box.
(In other words, there is no ground coming to your building via the power lines) All things grounded eventually lead back to this single grounding point.


Thanks, Jeff, for your support!

Actually I suspect this driven rod is not the sole ground, as it was added after the fact. But I have no idea where the ground in the shop is. I rent the space....So maybe I should disconnect the copper wire from the DC to the new ground rod?

The DC hose does not touch any metal on the machine. I was careful to figure that out last winter.

Replaying everything tonight, I realize that the inner support wire for my DC flex hose (not the bare copper wire inside the hose) doesn't connect to the metal duct work at the top. So that's the first thing I will do tomorrow and then retest. Maybe that wire, although somewhat insulated in the plastic hose, was collecting static that had nowhere to go.

If that doesn't solve things, I guess I need to take a fresh, comprehensive look at my grounding setup.

I certainly wasn't prepared for this a year ago. I expected to deal with the learning curve, break bits, etc. But static interfering with operation? Wasn't on my radar, and frankly ShopBot isn't particularly helpful on this either....

[Chuck Keysor]

Concerning the general nature of static and electrostatic discharges (ESD), this is a hugely complicated field. I am a degreed electrical engineer, (retired) and where I worked, we had two high-tech men who's job it was to test and harden complex microprocessor controlled products against the effects of ESD. These guys used Key Tech and Schafner ESD simulator guns to hit products under test with ESD events. They could spend a month to harden a system, AFTER they had become very experienced. While the work they did, and what they showed me, was above my pay grade, they made very clear that when dealing with ESD, just connecting a few wires and thinking you'd solve your ESD problems is as unlikely as winning the current $900 million lottery.

The very nature of ESD events involves super fast rise-times, of just a few nano-seconds. When dealing with such huge bandwidth signals, the stray inductances of ordinary wires reduces them effectively to nothing more than open circuits (yielding them totally ineffective, even though an old DVM will show that at DC they are solidly to ground. Instead, effective low-inductance ground planes need to be established,,,, (very hard to do, even with multi-layer PCBS), with all possible discharge paths needing to be by-passed for the very highest rise-time discharges.

Where I worked, our company could not tell our distributors/installers, "Oh, you are having ESD problems? Figure out how to ground our products properly...…. good luck..." No, to be able to sell our products, we had to sell products which our staff had hardened against ESD. And it was the work of these two brainy guys, working with the development engineers (of which I was but one), who had to harden our products so ESD would not affect them. (These staffers would go through many iterations of revised ground-planes, adding micro spark gaps, voltage clamps, small capacitors, and other such hardware to re-direct ESD discharges into non-damaging and non-disruptive paths. And their work also involved lots of software self-checking to make our products self-correct if fault modes were triggered. (Top level efforts as I recall, were to eliminate device destruction, and then eliminate/mitigate device operation disruption. Hugely time consuming to verify and validate all of the corrective measures...……..)

From the little I remember, our ESD guys subscribed to ESD journals and went to conferences on the subject, and met with people from all manner of industries, that starting in the 1990s, were hit with the cursed interaction of ESD with the then new fangled microprocessor based systems just then coming to market. And our guys made clear that all manner of responsible companies had come to the realization that to remain viable, that they had to come to terms with ESD and be able to bring ESD hardened products to market. The lesson here, is that if an analogous set of market forces had come to bear on Shopbot, they would have had to hire to big brains like we had, and they would have had to harden the Shopbot product line against ESD.

But perhaps the consumers of Shopbots are simply too disorganized, and willing to accept their ESD problems as being their own fault. Based upon what I saw in my work, the matter of ending the Shopbot ESD induced communication instabilities may well be corrected by ESD experts, hardening what Shopbot offers, instead of waiting for Shopbot to come out with some entirely new platform...… (But again, such an effort would not be a trivial undertaking...)

(And that raises the corollary concern...…. What IF Shopbot comes out with a new platform, and then we find out that it too has not been ESD hardened? Just being new, and being free from USB doesn't mean the ESD susceptibility will magically disappear..... We had our ESD issues, without having any USB ports!)

I didn't mean to ramble, and I am no expert in this. But I know enough to say ESD can't be fixed by just tossing a few ground wires here and there, and crossing your fingers...…….. Better luck with a rabbit's foot...… I would rather hope that Shopbot would hire a big-brained ESD expert to harden what they have...… Then that guy can work to make the new system be hardened against ESD..... Chuck

[Brady Watson]

Brian,
Do a continuity test using a multimeter on your bare copper ground wire inside the DC hose. You'll need a long insulated wire hooked to the spindle end of the ground wire to allow you to get your test leads on the other end. Test between the insulated 'helper' wire at the DC end and the DC chassis ground where your bare wire is terminated. It's really the only reliable way to test if your ground wire is doing its job & isn't broken. Then test your DC chassis ground (where the bare wire is terminated) and touch the ground lug in the electric panel or your driven ground rod. You should have continuity on both. Even a cheap HF meter will beep on continuity/a closed circuit path. This is the number 1 test method when troubleshooting anything electrical. Just because you don't know much about electricity now doesn't mean you're stuck that way - right?

To reiterate - you want a bare copper wire (.023/030 Cu coated MIG wire is fine) that is tied to the DC chassis (which is tied to electrical sys gnd) on one end & running through the hose and only folded over the end of the hose @ the DC foot end. It needs to function as an antenna with nothing metal touching the tip or the rest of the bare wire until it gets to the DC termination point.

-B

[bking1836]

I didn't mean to ramble, and I am no expert in this. But I know enough to say ESD can't be fixed by just tossing a few ground wires here and there, and crossing your fingers...…….. Better luck with a rabbit's foot...… I would rather hope that Shopbot would hire a big-brained ESD expert to harden what they have...… Then that guy can work to make the new system be hardened against ESD..... Chuck [/LEFT]

Looks like I picked the wrong week to stop sniffing glue.

[mclimie]

I wonder if an optically isolated USB connection would help.

Marc

[bking1836]

Brian,
Do a continuity test using a multimeter on your bare copper ground wire inside the DC hose. You'll need a long insulated wire hooked to the spindle end of the ground wire to allow you to get your test leads on the other end. Test between the insulated 'helper' wire at the DC end and the DC chassis ground where your bare wire is terminated. It's really the only reliable way to test if your ground wire is doing its job & isn't broken. Then test your DC chassis ground (where the bare wire is terminated) and touch the ground lug in the electric panel or your driven ground rod. You should have continuity on both. Even a cheap HF meter will beep on continuity/a closed circuit path. This is the number 1 test method when troubleshooting anything electrical. Just because you don't know much about electricity now doesn't mean you're stuck that way - right?

To reiterate - you want a bare copper wire (.023/030 Cu coated MIG wire is fine) that is tied to the DC chassis (which is tied to electrical sys gnd) on one end & running through the hose and only folded over the end of the hose @ the DC foot end. It needs to function as an antenna with nothing metal touching the tip or the rest of the bare wire until it gets to the DC termination point.

-B

Thanks Brady. I can definitely learn :)

Regarding the bare copper wire in the DC flex hose, right now it exits the hose and attaches to metal ductwork with a sheet metal screw. You are saying that, instead, I should run that bare copper wire from the dust foot, where it exits the flex hose and is clamped to the dust shoe, through the inside of the flex hose, out the top of the flex hose, and then directly to the electrical system ground?

Also, I am not sure what/where my electrical system ground is. That driven rod is new -- added by an electrician I hired. And it doesn't connect to the electrical panel in any way.

[Brady Watson]

Brian,
One long wire is best - you can use the duct as an electrical conductor between flex hoses - but to keep it simple, just wrap a MIG wire around a rag and let the DC pull it through the hole deal. Throttle it by hand obviously & don't let it get sucked into the DC.

Then....

Attach the wire to the chassis of the DC - which *should* be connected to the electrical system ground. Unless you get zapped or your hair stands on end every time you go near/touch the DC while it is running in dry conditions - then it's probably grounded to the electrical system just fine. Just make sure your bare wire is screwed to the chassis properly.

[Gary Campbell]

32139

32140


https://youtu.be/zKzjhp-yDkE

[bking1836]

Well, I think I fixed it, although I've learned not to celebrate too early. I will give it a week or so before I claim victory.

Today I systematically made a series of small changes to how the DC is grounded, each of which did not stop the stuttering/loss of position, until I removed the ground wire that runs from the DC to the driven rod and wrapped it around nearby electrical conduit instead. Now I am cutting without problems.

If that's the solution, it certainly tracks with anyone who said, "Don't have two competing grounds in your system!!!" It does not, however, explain why everything worked fine last winter once I added the driven rod and connected the DC directly to it. Oh well.

To summarize for the sake of anyone in the future who searches this thread:

In my particular case, I was able to consistently isolate the stuttering/loss of position to only when the dust collector was running, and even then only when I was actually making chips versus air cutting. So the hypothesis was that something was wrong with my DC grounding. I already had a bare copper wire clamped to the outside of dust shoe, running inside the flex hose until it exited at the gimbal joint where the flex hose connects to the metal ductwork. The inner wire of my flex hose connects to the bare copper wire where it exits the flex hose, and that bare copper wire is then attached to the ductwork with a sheet metal screw. My flex hose is also attached to a standoff of plywood and rigid foam that keeps the hose from contacting any part of the machine.

The change I made that works (at least for now): at the dust collector, there's a thick, bare stranded copper wire bolted to the frame that is attached to nearby electrical conduit that runs directly to the electrical panel (instead of being attached to a driven ground rod, which was likely creating a situation where I had two competing grounds).

Notably, the frame of my ShopBot has no ground wires at all.

I will report back if anything changes. Thank you all for the help!!!!

Back to work....

Brian

[coryatjohn]

You should read Gary's PDF on grounding and follow those instructions. Not having the frame of your machine grounded is just asking for problems.

[bking1836]

You should read Gary's PDF on grounding and follow those instructions. Not having the frame of your machine grounded is just asking for problems.

I agree. For the sake of clarity, I wanted to state that the problem seems to be fixed and explain how it was fixed -- with a note that my frame isn't grounded, so that's likely NOT the cause of this particular problem. That doesn't mean it shouldn't be grounded. That is next....

[bobmoore]

thanks for the report back even though I am sure you are very busy now.

[bking1836]

Well, good thing I didn't celebrate yet. I have had some jobs cut without incident, but at this point I am back to a 100% failure rate if the DC is running, and a 100% success rate if it is not. If necessary I will run certain jobs with no DC. But I make a lot of trays, and a 1.25" diameter bowl bit taking 1/4" passes at 16000 rpm requires dust collection given the massive amount of chips.

I've done everything in Gary's PDF about static reduction in dust collection systems. So even though the problem only happens with the DC running, I guess either my DC grounding is incorrect or it's something else, like the CNC itself not being grounded directly to the panel. So I will hire an electrician to ground the ShopBot; and while he is at it, he can take a fresh look at my DC ground.

I am not at a full panic yet, but close....the work is mounting, and I can't get any of it done right now.

[Ken Sully]

Just a final thought. How old is your DC? Could you have a motor failing causing electrical noise in the ground leg? Seems odd the only time you have trouble is when its turned on.

[bking1836]

Just a final thought. How old is your DC? Could you have a motor failing causing electrical noise in the ground leg? Seems odd the only time you have trouble is when its turned on.

The DC is an Oneida Gorilla Pro that’s less than one year old. Seems to work perfectly.

[Burkhardt]

Get somebody with a battery operated (to avoid just another ground issue) oscilloscope to probe the various sections of your wiring in a systematic fashion. Once you "see" the noise (including frequencies and amplitudes) you have a handle to test changes immediately. Otherwise you may just continue the hit-and-miss experimentation. There must be something unique about your setup so that the standard recipes don't work. Right now you don't even know if this is high frequency noise (like from VFDs), if it is radiated or conducted, or if this is just AC leakage.

[bking1836]

I rigged up a long wire lead to one of the probes of the multimeter and checked continuity, which exists from the bare copper wire at the dust show all the way to the ground bus on the electrical panel. I don’t know enough to determine whether the continuity is “good” or however you’d measure it, but the multimeter beeps. Sometimes it’s a bit of a staccato beep. But it beeps.

Also grounded the frame.

Any ideas?

[EricSchimel]

Try it with the grounded frame and report back!

[bking1836]

Try it with the grounded frame and report back!

Grounding the frame didn’t stop the problem.

[Brady Watson]

Grounding the frame didn’t stop the problem.

How exactly did you ground the frame? Did you put the wire on an exposed bolt or did you drill into the steel & attach a lug/ring terminal etc?

[bking1836]

How exactly did you ground the frame? Did you put the wire on an exposed bolt or did you drill into the steel & attach a lug/ring terminal etc?

I sanded off paint to bare metal and attached a heavy duty alligator clip to the frame with a bare copper wire running to another heavy duty alligator clip, which is attached to the conduit (also sanded away paint) that runs to the electrical panel.

[Brady Watson]

It seems the DC is the culprit. As some have mentioned, it is completely possible for the motor to have a goofy winding in it that causes electrical noise. Static is generally a problem in the dead of winter when the air is really dry. It's probably plenty humid where you are being so close to the lake and with the number of storms that have passed your way recently. Did you have this same issue during mid summer?

As a means to an end, I think only a professional motor repair guy would have the know how and equipment to find out if the DC motor is wonky or not. The manufacturer probably doesn't have a clue about static other than making sure their electrical and chassis grounds are terminated at a common point.

The other thing that *may* cure the problem is some kind of line conditioner that will clean up the electrical signal. Electrical noise & conditioners are very common in manufacturing...there can be noise issues with spindles, DCs, pumps, hi-freq welders and plasma cutters...and not to mention your electric service itself can be noisy as well. Without an O'scope you have to play the guessing game.

[bking1836]

It seems the DC is the culprit. As some have mentioned, it is completely possible for the motor to have a goofy winding in it that causes electrical noise. Static is generally a problem in the dead of winter when the air is really dry. It's probably plenty humid where you are being so close to the lake and with the number of storms that have passed your way recently. Did you have this same issue during mid summer?

As a means to an end, I think only a professional motor repair guy would have the know how and equipment to find out if the DC motor is wonky or not. The manufacturer probably doesn't have a clue about static other than making sure their electrical and chassis grounds are terminated at a common point.

The other thing that *may* cure the problem is some kind of line conditioner that will clean up the electrical signal. Electrical noise & conditioners are very common in manufacturing...there can be noise issues with spindles, DCs, pumps, hi-freq welders and plasma cutters...and not to mention your electric service itself can be noisy as well. Without an O'scope you have to play the guessing game.

It's much dryer in Milwaukee than people think. My shop is in the low 30% humidity these days. This only started happening once the humidity dropped.

An electrician with experience with dust collection in industrial conditions is coming tomorrow.

[chiloquinruss]

"It's much dryer" how about a hot plate and a pot of water to raise the moisture/humidity inside the shop? Where my shop is located is high mountain desert and when its dry its dry! I wish you well on your quest! Russ

[bking1836]

Update...ShopBot tech support had the clever idea to run a job with the DC running but with the flex hose removed from the dust shoe (I simply draped it over the ductwork near the ceiling). Two jobs cut without incident like that. So the issue appears to be static in the flex hose itself, which obviously isn't draining sufficiently despite the bare copper wire running through the hose and attaching to the metal ductwork at the top.

Then an experienced electrician came to the shop and looked at my setup. He immediately said that it's not sufficient to run a bare copper wire through the hose and then attach it to the ductwork, and then let the ductwork be the "raceway" for the static until it reaches the DC. Instead, he said the bare copper wire and the flex hose wire, which are bonded at the top of the flex hose, should connect at the top of the flex hose to regular #10 insulated wire, which is then tacked to the ductwork with circle terminals at the beginning and end of each section of ductwork. That way, the ductwork and the ground wire become one and run all the way to the DC itself without any opportunity for interference. And finally the #10 wire continues directly from the DC to an open terminal on the ground bus of the electrical panel. All together, he said that will create a tighter pathway to drain static without relying on metal ductwork and electrical conduit.

So that's tomorrow's plan...

[bking1836]

Well I am at a loss. I beefed up the grounding per the electrician's recommendations, and the continuity readings actually improved significantly -- reading continuity and essentially no resistance in the line almost immediately, whereas before it sometimes took a few seconds for the beep and the resistance reading often jumped around a lot. The ground also terminates in the ground bus directly on the panel. But I am still experiencing the same stuttering and then position loss/failure of the job. I even opened all 3 blast gates to reduce the flow/static production a bit, and it didn't matter.

So I removed the flex hose again and rigged up my Fein Turbo vac to a different 4" flex hose and attached it to the dust shoe. Then I ran a job without problems. (The Fein actually did a decent job except for through cutting, where it left most of the chips in the channel).

Could the problem be the flex hose itself? I will switch it out with a different brand and see if anything changes. Any experience with the Rockler antistatic 4" flex hose?

If changing the hose doesn't solve the problem, unfortunately I will have to transition to a shop vac workaround rather than keep trying to solve the problem. I have to get back to my jobs for paying customers...

[kartracer63]

Call Dick Wynn. He's very knowledgeable when it comes to dust collection hose.
https://wynnenv.com/static-control-hose/

[jerry_stanek]

I use this from home depot and have not had any problems since. It has been going on 6 years now. I cut mostly PVC so there is a lot of static

https://www.homedepot.com/p/Everbilt-4-in-x-20-ft-Dryer-Vent-Duct-BTD420HD/203626495n

[bking1836]

Update: I added an additional flex hose standoff and rigged up a bungee cord to even further separate the flex hose from the machine (the taller standoff is the addition). Even though the hose NEVER touched the machine before, now there's even more distance between the hose and gantry.

32222

So far, no problems! But it has also been a bit warmer with more humidity, so I am not declaring victory...yet.