Losing Communication

[Tim Summerer]

Hey,
I know this is a common problem, and I apologize for adding one more post about this, but I need a hand figuring out a lost communication issue.

I have two ShopBot machines. We're using them in a production (16/hr day) environment.

Machine 1 is a PRT Standard 144x60 with RBK box. Wood Frame. 4hp Spindle. Newish Levano PC with 8 GB RAM

Machine 2 is a PRT Standard 96x48 with original box. Steel Frame. PC Router. Old Dell PC.

Both machines have been running at this pace for well over a year. They give me trouble from time to time, but on the whole, perform OK. Lately Machine 1 has been pretty much useless because it keeps losing communication. I've talked with ShopBot and they are having me run a bunch of tests to try to narrow down the problem (they've gone home for the day, so I'll see if anyone here has some ideas).

Attached are the tests I've run and the results. To me, it looks like a grounding issue. It's cool and dry here right now, and nothing else has really changed except the weather.

I've done what I think of as a pretty good job grounding everything. I've got copper wires in my DC tubing, metal tape on the outside of the tubing, all the axis connected with grounding wire, etc. I know there are a lot of theories and opinions regarding grounding so I need some advice from ShopBot users regarding what changes/improvements I may need to make.

It's extremely confusing to me that it seems like Machine 2 is causing the problems in Machine 1. I've attempted to keep them pretty well separated electrically, but they both definitely share the dust collector.

Here is a diagram of my setup. I'll also attach the pdf. What do you think and what would you recommend?

https://www.lucidchart.com/documents/view/4589-db48-50c1000b-87aa-7b750af069f2

Red lines = 3 wire cable - black, white, ground
Green lines = 1 wire copper ground

Machine 2 has a metal frame and I haven't worked on attaching it's frame to electrical ground. Should I do this?

Is the wire in the DC tubing supposed to connect to the frame of the machine? Or does that make a (mysterious and elusive) ground loop?

Thanks for your help

[dana_swift]

Hello Tim!

In your test grid "tests.pdf" how reliable is the green Succeed case? Is it always? If so the noise in your shop is exceeding the amount USB can withstand.

First be sure the computers are set up according to the black viper minimum configuration. No unnecessary background activity starving the usb port. (a possible culprit).

Two possible electrical remedy's. First is buy a usb isolator for the machine that is hanging up. Then ground issues between the computer and the shopbot cease to be a factor. USB isolators are not common, then neither are shopbots that freeze, you may have to order one off the internet, I dont know of any place in town here that carries them. A USB isolator can break a ground loop through the USB cable also.

If I read your diagram "shopbots" correctly, you are using flex conduit for part of the ground to shopbot 1. Run a real wire. Around 16 gage or bigger. The red connections in your diagram are a possible source of trouble if there is a neutral that is connected to that green connection shown coming from the box. Ground loops are a huge noise generator. (The most likely culprit).

Ground loops can usually be found with a clamp-on ammeter. Its common to find several AMPS of current flowing in circles in a ground loop. Plenty of current to cause a voltage shift adequate to interfere with an LVDS signal (the electrical method USB uses).

The ground loop issue would be made worse with different combinations of machinery running. My nickle is betting on that issue.

Hope that gives you a couple things to check, and probably remedy the trouble.

Keep us posted.

D

[Brady Watson]

1) Machine 2 has a metal frame and I haven't worked on attaching it's frame to electrical ground. Should I do this?

2) Is the wire in the DC tubing supposed to connect to the frame of the machine?

3) Or does that make a (mysterious and elusive) ground loop?



1) No. Electricity follows the path of least resistance. You want a straight shot to electrical ground on your system. If the ground cable from the dust foot to the dust collector is 25 feet long, and there is a wire/cable from the dust foot to the frame of the machine...which has a ground cable attached to the control box and it is only say 10 feet, guess where the electricity is going to go? A 10' wire has less resistance than a 25' one. Then the electricity has to go somewhere - which could very well be your control board and processor, or the USB cable itself.

2) No. See #1.

3) Yes. You just want a straight run of light BARE copper wire inside the dust collection tubing. It should ONLY be terminated at the DC and nowhere else. Think of it as an antenna for static - only one end gets connected. Non-flux core MIG wire works well for this application.

There are 3 possible reasons for communication to **** out. The first is the computer itself and it's USB hardware. If in doubt, a $30 PCI to USB card is cheap insurance. Pop it in the computer and plug the 2.0 hub, then the Bot into it. Second, static electricity generated from cutting and dust collection - which is usually cured with a single terminated bare wire through the hose. Third, and not often considered, is environment electrical noise. Sometimes 'dirty' power, electrical and magnetic fields in the working area can cause communication problems. Remember, the tether between the Bot and the computer runs on 5v (USB is a 5v device) - so any electrical signal (including static and EMF) can 'stand on' that 5v signal and mess it up. Isolating and curing this type of situation can be tricky and complicated, depending on the source of the noise.

-B

[Tim Summerer]

Thanks for taking a look Dana,

First a few notes on the Tests. Woodcut is opposed to Aircut.
We're trying to totally cease production so we didn't run each test exhaustively. The succeed in Test 4 may be somewhat unreliable - this test was machine 1 cutting by itself with the DC on. I believe my guys tried this this am and it didn't work (but that was before we had our fancy Test Grid). I think if a failure due to Grounding is going to happen in a machine, it's likely to happen no matter which machine is cutting.

I've done everything I know to make sure the computers are set up appropriately. I'll double check that against Black Viper.

I'll look into a USB isolator - I had researched it at a previous time.

Regarding the diagram:
The flex conduit is what runs the power to the Outlet Box which provides power (and ground) to Machine 2.

Currently to ground Machine 1, I have a wire running from the frame to the grounding strip inside the RBK box. It is my understanding (possibly totally wrong) that this ground is then carried out with the red cable (which includes black, white, and green wires) to the surge protector, then breaker box, then rod.
Should I instead be running Machine frame to rod, RBK box to rod, etc?

[Tim Summerer]

Brady,
Thank you as well for your thoughts.

I've got one question right off the bat.

Here's a simple layout of our facility This is looking at the machines from eye level. (kinda). You can see that the wire to carry away Machine 2 static has to travel past/over Machine 1. I've definitely always wondered if it's quicker and easier for the static to just travel down and into Machine 1.

https://www.lucidchart.com/documents/view/416d-72cc-50c130ed-a452-3b600a7c4e7c

So... What can I do to avoid this. Obviously the first step is to not let the DustCollector grounding be connected to the bot. It's easy to keep the internal copper wire from touching the SB frame, but what about the spiral of stiff wire in the DustCollection flex tubing. Will/Can static jump from that to the machine frame?

Would there be an advantage to jumping to ground faster and at intervals along the Dust Collection path? (The orange parts in my diagram)

[Brady Watson]

Tim,
The spiral steel wire in the dust hose is there for structural support ONLY - It should not be relied upon for grounding, because it is insulated from the inside of the tube - completely encapsulated in plastic. Therefore, this is why a bare copper wire inside the tube is the preferred method. I would not worry about static jumping from this spiral wire to the machine. Remember - path of least resistance - the static will gravitate towards the bare copper wire instead of the spiral encapsulated in the hose.

-B

[Joe Porter]

Brady, thanks for the "antenna" description of the ground wire in the DC hose. This finally clears up what you all have always talked about as far as grounding the DC hose. You know, it pays to always read these technical type posts even if you are not having that particular problem and not really able to follow the conversation. What you might not understand now maybe will clear up down the road. Especially when you and Dana get to talking, waaay down the road for me....joe

[Bob Eustace]

Dana could you kindly tell me what an isolated USB is please? Fantastic inciteful information from you and Brady as usual - thanks for adding to our knowledge.

[Tim Summerer]

Here's an update for the last few days.

I had an electrician come and take a look at things, while he was clear that he was not overly familiar with static electricity as it applies to sensitive machinery, he checked all our grounds and made sure that things looked ok in the breaker box.

Next, Dana Swift came by to have a look. We ran both machines and tested the grounds with a voltmeter and found them to be good. Per Mr. Swifts instructions, I meticulously went through Black Viper's recommendations to disable any unnecessary background programs.

None of this helped.

So, since the machine seemed to prefer to lose communication in about the middle of the table, I went back to inspecting mechanical problems. I decided that my wires were showing a bit of age, and decided to replace them. I disconnected EVERYTHING and started fresh. I was super-careful and my machine looks like she ought to be happy. Unfortunately, no. Still losing communication when Machine 2 is running (and maybe when machine 1 cuts too, I haven't got that far yet [ still doing aircuts]. I don't want to shut down machine 2 so that I can test machine 1. The fact is they have run together in the past and they must go back to running together in the future).

We had been running Machine 1 with an iMac for over a year, About a month ago, I bought a new PC for the ShopBot and moved the iMac to a different department (we didn't have any problems after the transition, so I thought things were fine). I pulled it back to the shop last night and tried it with the machine. No luck there either. It still lost communication frequently while aircutting.

All of this has been with no dust collector hose attached. I had been curious about whether charge was traveling through the dust collector system from machine 2 into machine 1. To rule this out, I have been simply aircutting with machine 1 and there is no dust collector tubing (or any other physical connection (besides the concrete floor) between the two machines.

I have a USB isolator ordered. It should be here the day after tomorrow.

In the meantime, there is a green light in the middle of the communication card. It says 5v near it. This light doesn't always remain lit. I have watched it (with the box open and on) while the other machine runs. From time to time the light will go off. Sometimes for an instant, sometimes for several seconds. I'm guessing this is bad. I checked the voltage to the board (the one that the communication card, inputs/outputs/etc are attached to) while watching this light. It remained at 5 volts whether or not the light was on. I did not see any fluctuations or changes. Next, I switched my meter to AC voltage and watched the voltage into the box (measured from the assembly where the power wires go in and which contains the on/off switch). It held steady at 120 volts - again no spikes or drops before or after the light flickered. Finally, I stuck the prongs into the power strip that the control box and computer is plugged into. Still, it remained steady. Any ideas about why this light would turn on and off? Any solutions?

Bob, from my understanding, a USB isolator changes a USB cable's electrical signal into pulses of light, then back again. In this way, the computer and the equipment won't be physically connected. Further (and probably more importantly) there won't be multiple routes to ground. Right now, the control box can get to ground by going through it's standard cables OR it can be grounded through the USB cable--> to PC -->to PC's grounding cables (and vice versa). These multiple routes to ground create a loop, a loop is an antenna, an antenna picks up my fluorescent lights, second router, and the radio station down the road. All this noise picked up by the antenna screws with shopbot. So...an isolator could break this cycle. I bought mine from this company http://www.acromag.com/catalog/746
They seem to specialize in isolation. I'll report on it when it arrives.

The thing that perplexes me is why this should suddenly be an issue - after more than a year of running these machines 80 hours/week.

[dana_swift]

Tim- I am still most suspicious of the Windows 8 configuration. The measurements we made show the isolator very unlikely to help, but it doesn't cost much to try. If you have an alternate computer you could use as a controller for a while, that would be my next suggestion. There are too many services on Windows 8 that cant be turned off it seems. Thanks for the update- D

[derekgirven]

Hi,
Just a though we have had a lot of problems with our machines loosing contact to the port . try split the power lines going to your spinal and box to separate isolater on your db board. some how I was getting feed back (don't as me how). i.e plug one into another socket. may work for you too.

[dana_swift]

Bob- sorry I just noticed your question regarding "what is a USB isolator?"

I will start out with what is USB?

USB is a bi-directional serial data system with several capacities, the system automatically adapts to the slowest capacity device. It also provides some limited power to run things that dont need much- like thumb drives, small hubs, etc.

Now what is an isolator?

An isolator acts like "wire" with no physical electrical connection from one side to the other. So anyone would reasonably ask- how do you send power across such a thing? Answer: good old transformers. Well really modern high-tech transformers, RF transformers instead of 60hz transformers. The power capacity of an isolator is approximately 95% of the original capacity of the computer it is plugged into. In a nutshell - plug it in and dont worry about it.

So- how does data get across the "gap"? - optical isolation. Data going each direction drives LED's that get connected to photo-detectors on the other side. No electrical connection.

Since power is transferred from one side to the other, the isolator only works when the power source is on one side (the male usb plug) and can only provide power on the other side (the female usb plug).

And that last little thing- signaling the capability of each side to the other- that is done with optical isolation also.

What you end up with is a USB cable that can tolerate very high voltages from one side to the other. Usually over 1000 volts before the system fails catastrophically. Some isolators are over 3000 volts, then I wouldnt want to be working on a computer with 3000 volts on the other side of that little cable would you? I dont even want 50 volts..

How much differential ground voltage can USB take with standard cables? Conceptually none, but in reality about 0.75 volts. How much can old fashioned RS232 serial tolerate? About 7 volts. Thats a factor of 10 difference, where the "new and improved" serial system is not as tolerant as the old serial system. Both of which were designed based on the assumption that there was no ground differential voltage between the sender and the receiver.

When I was at Tim's shop, I measured the ground differential voltage - which was usually around 0.005 volts, with a maximum of 0.025 volts or so during air cuts. We did not cut anything so no dust was going through the ductwork which can change that 0.025 to a much higher number.

What I was checking for is ground loops, that was clearly eliminated as a problem source. That leaves two suspects- Windows 8 and dust collection static. Tim has tried another computer without any change in reliability so that leaves us with dust collection static buildup.

An isolator might help with that problem, but its a shot in the dark.

Good news is USB isolators can be purchased for under $50 on Amazon.

Now to deal with the real problem- static charge in the dust collector. For that, I am devising a meter to read how much static we have. Then I intend to try different things to lower it, and rather than just guess how effective each possible solution is, I intend to measure it and remove the guesswork.

Hopefully that is a full answer on USB isolators, and how it pertains to this installation.

I will now rotate my hat back from "electrical engineer" to "woodworker".

D

[Joe Porter]

My head hurts, I think I'll go lie down....joe

[Ken Sully]

Tim,
I have been following the forum for a while and looking forward to my first shopbot next spring. I was in the x-ray business for many years and chased grounding issues and ground loops. I have attached an article you may find useful.
Ken

[CantologyLLC]

First post - been lurking for too long. Seems a good place to pipe in. Been running my Desktop hard for over a year with intermittent comm problems. Followed all the usual advice and problems have become much less frequent. But last Saturday morning I had three nasty glitches - all the same: caused bot to lose track of X axis, shut off the router, but kept driving! Tore the material off my vac table pulling 24"hg! Not pretty. Couldn't think of anything else to do to combat this ambush of my day. So I installed the latest beta, which I had heard has more robust comm. No problems since. And I love the new interface. But I don't see the beta discussed anywhere on the forum. Am I missing something?
-Will

[Bob Eustace]

Thanks for the excellent explanation Dana. Does going optical reduce the speed at all do you know? If isolated USB only has one port what do you do with the spindle USB? Sorry for all the questions! Cant wait for you to perfect your static measuring gadget.

[dana_swift]

Bob- the speed of opto-electronices "can" be extremely fast. There is nothing inherently speed limiting about the optical isolation technique.

The person designing the isolator must choose appropriate parts to avoid speed issues, and to achieve efficient power transmission, etc. Nothing is automatic. As consumers, all we can do is buy something and hope the designer did their homework.

Fiber-optic communication is just a long distance form of optical isolation. The speeds they achieve with fiber optic data are just amazing. USB does not run anywhere near that fast, so the presence of the isolator "should" be transparent. I dont recommend blindly putting them in the system, but its worth a try if a problem shows up. They just plug in, so its real easy to unplug and remove them.

For what its worth, I am presuming the hub is next to the computer, and the isolator would be inserted in the cable from the shopbot that plugs into the hub.

If several people try isolators, it will be interesting to post some info on how it is affecting their USB speed test, and any other results they may be noticing. Any takers?

D

[adrianm]

First post - been lurking for too long. Seems a good place to pipe in. Been running my Desktop hard for over a year with intermittent comm problems. Followed all the usual advice and problems have become much less frequent. But last Saturday morning I had three nasty glitches - all the same: caused bot to lose track of X axis, shut off the router, but kept driving! Tore the material off my vac table pulling 24"hg! Not pretty. Couldn't think of anything else to do to combat this ambush of my day. So I installed the latest beta, which I had heard has more robust comm. No problems since. And I love the new interface. But I don't see the beta discussed anywhere on the forum. Am I missing something?
-Will

You have to apply to join the beta forum. Discussing the beta releases on the main forum is not encouraged.

See the beta notes on the page you downloaded the beta from.

[Brady Watson]

So I installed the latest beta, which I had heard has more robust comm. No problems since. And I love the new interface. But I don't see the beta discussed anywhere on the forum. Am I missing something?

Will - Welcome to the forum & thanks for joining in. The beta control software doesn't get as much attention and interest for the average user. The latest beta certainly brings a lot of new functionality and a revised look to the interface. There are a number of specialized enhancements that you can read about when you install it or via the SB main site beta section.

There is no secret handshake or special beta forum area for discussing the beta version of SB3. So feel free to talk about it all you want. I'm afraid the SB3 beta isn't quite as anticipated as the Vectric releases ;)



You have to apply to join the beta forum. Discussing the beta releases on the main forum is not encouraged.

See the beta notes on the page you downloaded the beta from.

You are on the ShopBot Forum. The Tardis is translating for you. Do you know many fingers am I holding up? :D

-B

[Bob Eustace]

Brady this is a fascinating thread! This problem seems to affect all model Shopbots, so to the layman, (read - dumbell) the problem would appear to be the computer driving them? Does the answer lay in sticking a USB stick directly into the bot bypassing all the unknowns? Could this be made a retrofit option? Have been comms error free until I read this topic yesterday - first time we had ever cut blackwood. Weird how it always happens on jobs where you havent used C3 and have been tooooooooo lazy to write down the start co-ordinates!

A wonderful winter pastime for Dana could be to write a little routine that plonks this info in a separate file?????

[jerry_stanek]

I run the beta and it does run better the version 3.6.44

[Bob Eustace]

OK should one give the beta a bit of a bash to get more robust communication? What precautions are needed before installing please. Currently running 3.6.36 for a year and never changed firmare from 202. Any advice greatly appreciated.

[jerry_stanek]

You should update your firmware with each new version.

[adrianm]

There is no secret handshake or special beta forum area for discussing the beta version of SB3. So feel free to talk about it all you want.

You are on the ShopBot Forum. The Tardis is translating for you. Do you know many fingers am I holding up? :D

-B

So why when we join the ShopBot beta forum are we told not to discuss the beta software on the main forum then?

I don't mind either way but it seems there are mixed messages.

And yes there IS a ShopBot beta forum (I do know the difference between Shopbot and Vectric ;)) with people on it discussing the beta release.


YOUR FEEDBACK: To report, you can just send us an email at support with "Beta Testing" in the subject line. Or, we also have a "Beta Area" on the "Talk ShopBot Forum" for reports and discussion of your experiences with beta versions of the software. This section is moderated by the ShopBot Development Team when we are actively testing a new beta version. If you would like to participate in this forum section, just send an email to support and indicate that you would like to receive a logon to the 'Beta Area'. It would be helpful to us if you let us know the type of tool and type PC and operating system you are running. We will give you a call if we need more detail. Please realize that we really appreciate your feedback. We may not be able to immediately reply to all posts on the forum or to emails you send -- but we are very attentive to them and will try and keep everyone informed about what's going on with the beta.

[jerry_stanek]

So why when we join the ShopBot beta forum are we told not to discuss the beta software on the main forum then?

I don't mind either way but it seems there are mixed messages.


That was the same thing I said to Brady and the post that I deleted.

[Brady Watson]

So why when we join the ShopBot beta forum are we told not to discuss the beta software on the main forum then?

I don't mind either way but it seems there are mixed messages.

And yes there IS a ShopBot beta forum (I do know the difference between Shopbot and Vectric ;)) with people on it discussing the beta release.

Interesting...Sorry...someone didn't send me that memo.

-B

[garyc]

Brady...
Check your inbox, you have both the memo and handshake :D

Adrian, et al....
There is no "secret" to the Beta forum. It is visible only to those that have asked to participate. This is so that the occasional visitor to the forum, especially one that has a problem, is not confused by reading posts that are specific to the Beta that may not apply to the current release version.

The verbiage that I included in "the Beta Tester" letter (which Adrian posted an excerpt from) was similar to other Beta forums that I participate in and may (especially when posted in the context Adrian did) have been stronger than needed. Sorry if this has created any confusion.

[adrianm]

Blimey, feel a bit kicked around in this thread. I'll avoid directing people to or quoting from the beta download page in future then. Not sure how that gets construed as secretive though. :confused:

This transatlantic language barrier is getting more confusing by the day. ;)

[Brady Watson]

Thanks Gary.



This transatlantic language barrier is getting more confusing by the day. ;)

I know m8...If we only spoke 'English'... :D

-B

[Tim Summerer]

Hey everyone,

Finally got our problem solved. Here's a list (in order) of all the things we tried. With each change we tested on two separate computers.

-Replaced USB cable (installed old ferrite core)
-Bought new USB hub
-Checked Grounds with Electrician
-Checked Grounds/Ground loops with Dana Swift
-Removed excess PC processes per Black Viper
-Replaced all wires on machine
-Bought USB isolator
-Rebuilt dust collection tubing with metal pipe (grounded at collector motor)
-Bought new USB PCI Express board
-Bought Battery Backup
-Tried Beta version

After all this Shopbot Support finally ran out of ideas and agreed to send us the newer version of their Communication Card

-Installed newer version Comm Card

Also, while the card was in transit, Frank from support asked me if the brushes in our Machine 2 router were sparking a lot. He wondered if this signal was being picked up and amplified by our Machine 1 VFD. I didn't see excessive sparks (we cycle through routers pretty fast, so I know when the brushes are wearing out). Anyways, I moved our machines further apart. (Our new DC piping allowed this). So while they were previously ~3ft apart, now they are ~7ft.

-Moved Shopbots away from each other

Finally. No problems.


Of course, hindsight is 20/20. Maybe some of the steps were unnecessary and others should have been done first. The important thing is that it is working now.


Our USB isolator did not slow down the comm speeds. On our original Comm board, we were getting speeds around 76% before and after the isolator.

I bought two different USB 3.0 PCI cards. I don't recommend these on a Windows 8 machine unless the manufacturer states that it's compatible. (plus there's really no reason to go with 3.0 because shopbot doesn't utilize it)(but it's all the store had) While these did function (and the sales team told me they were plug and play), Windows installed some sort of default driver (because the mfg didn't have a Win8 driver), and the speed dropped to the 60's. I've since gone back to the stock hubs.

On the whole this has been a very frustrating experience. I wish these machines were more robust in the communication department. Glad to finally get back on schedule.

[jkaras2000]

Hey Everyone: Very interesting posts. I think I would like to try a USB ISOLATOR. Can anyone suggest a brand/model that they have had good success with. Also, would I need two USB ISOLATORS, one per each usb wire coming out of control box? I may also download and try the Beta version to see if there is an improvement. Happy & Healthy New Year To All. Joe.

[dana_swift]

Joe- as near as I can tell the devices are fairly generic. Although there must be some tiny difference between units, try an inexpensive one. I have not tried this brand, but its probably as good as any:

http://www.amazon.com/Multi-purpose-USB-Isolator-Built-in-DC-DC/dp/B00899UVGW/ref=sr_1_1?ie=UTF8&qid=1356897061&sr=8-1&keywords=usb+isolator

Its under $40 plus shipping.

The primary value of an isolator is to break ground loops. If that isn't a problem you are having they don't help. There "might" be some value in dust collection static interference with USB. The isolator should not introduce any new problems if it doesn't help. There are no drivers or anything. To the system it just appears as "cable".

Which USB lines need them? The ones that are part of a ground loop. What the isolator does is break the connection and stop circulating ground currents. How do you determine which ones those are? Either a clamp on ammeter which reads currents under about 10 amps full scale. If you have ground loops it will be showing current in the ground and usb cables that conceptually has none. A second method is to check for differential ground voltages. If current is flowing in ground wires, the resistance of the wires generates a voltage which can be measured with a plain-jane ac voltmeter. If you are seeing a difference in ground voltage from one point in a ground system to another when the equipment is running over about 50 milli volts, you have clear evidence of a ground loop. By 500mv you have enough ground differential to mess up USB.

I am accused of providing too much information. I will stop there-

Let us know what your experience is!

D

[Joe Porter]

Dana, your responses provide more help than you can imagine. Please keep it up. I am working up to the day when I feel like I can ask an intelligent question. Thanks....joe

[jkaras2000]

Thanks for the thorough response Dana: I don't mind reading a lengthy response at all. I appreciate your covering all the bases. I will check out the USB Isolator Link you posted. Before I ran a copper line through my air vac hose, I used to get fouled up with Lost Comm Messages fairly often. After adding the copper wire, it was like night and day. One day not too long ago, I was running the bot, and had a few Lost Comm's within a three hour time period. (Very Frustrating) I decided to sleep on it and get a fresh start in the morning. Low and behold it cleared up, and in fact the Bot is cutting as I type. Don't know what was up. I have also wrapped a copper wire on the outside of vac hose and is grounded to vac along with inside wire. The notion of the USB Isolator just seemed like a simple thing to do to help insure less or even no Lost Comm's while running a file. Joe:cool: