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jrw
10-13-2001, 10:26 PM
I have a new prt96 and I am getting a small electrical discharge when I touch either the machine or the z-zero plate after cutting projects, I have a ground wire from the machine and the control box, directly to the water meter ground location, so I know the machine is well grounded. I have a 650cfm dust collector connected to the dust port and I have connected a bare groung wire to the clamp that holds the dust port coiled around the outside of the hose and connected to the collector. If I am cutting a small part I will get nothing, but the larger the file, all be it quite small, the bigger the poke. I have tried to measure it but have had no luck. I know this can't be good

danhamm@abccom.bc.ca
10-13-2001, 11:01 PM
Jay,
Probably you are moving about and becoming statically charged,and when touching anything that
is grounded you discharge, other than that check
the grounding from your panel to the water meter
it may be corroded..

Wdyasq@yahoo.com
10-14-2001, 10:08 AM
Jay,

Is the dust collection system properly grounded?? Dust flowing can create static. It has actually been known to cause enough spark to start fires in dust collection systems. The static electricity has also been known to ground through the bearings of dust collector blowers and ruin the bearings in short order(I know this problem personally).

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

sea_nc@bellsouth.net
10-14-2001, 01:40 PM
Jay,
As the replies above indicate, dust colllectors do generate a lot of static, especially during high flow during heavy cutting. The ground wire I've seen on dust collection hoses of large venturi vacuums and in-house vac systems is actually a thin copper alloy strip that extends around and into couplers at either end of the hose (rather than being attached to an exterior hose clamp). It may be worth looking into them for alternative hose grounding ideas.
Is the entire building grounded to your water meter ground? I don't know what your shop wiring looks like nor am I an electrician, but I would run *separate* ground wires from control box to building ground and from ShopBot tool frame to building ground to minimize static discharge from tool frame directly to control box. In rare cases with some control boxes stray current going to the control box can be enough to make the motors move.

My two cents,
Dave

garbob
10-15-2001, 09:03 AM
I had the same problem. I also talked to someone who had a small explosion at the dust pickup end where it collects dust from the router head.

I used to get mammoth shocks from the table x or y rails if I touched them while I was holding the plastic wand of my shop vacuum.

I tried several things at once and haven't had the problem since.

I grounded all of the rails and major components that are not directly connected to the steel table, including the x rails (this was probably overkill, but all the bolts on one rail had plastic shims on them). I also ran 14 gauge antenna bare copper stranded wire through all of my vacuum pickup and wands and put automotive male/female connectors at any joint that I might want to break apart. I also ran a ground directly into the container for my Sears dust collector which just terminates at that point. My dust wand is a seperate piece of hose and it is connected to a manifold that also provides shutoff and vacuum adjustment for all of the hoses including the vacuum table (which I never use). On the manifold I just use a terminal block, which I shorted out across all terminals, and this provides connections from all of the table, machine, vacuum table and dust collector. The wires running through the hoses are brought out to the surface at the sleeve connectors (through a small drilled hole) so that they can be connected to the next segment there. I have never had problems with the 2 1/2" hoses plugging up due to the wires, only when I am dopey enough to suck up something too big to go through the hose, without the wire. It took some time but it was worth it. I have not had a problem since.

jrw
10-16-2001, 07:57 AM
Well, I have found the source or sources. I set up a series of test lights that would register between 1 to 5 volts and could not get them to trip when I got the discharge, so, I took all the ground wires off and started from scratch. I cleaned the x;y rails and applied a light conductive oil, kind of like what we used to do with the old slot car tracks we had when we were kids. then I increased the size of the ground wires where it hooks to the table and also put a larger wire both thru as well as around the dust collection hose(I had only wrapped the outside of the hose before). Then after checking continuity, which was strong. I fired it up and bingo, no more poke! Then yesterday I was cutting some parts and touched the machine and
got that same discharge, check this out Dan, I thought of everything I had done and one thing came to mind MY SHOES, I have a pair of nike running shoes that I wear, these shoes, when I go to turn the tv on and touch the antenna I get a shock. How bizare is that, I changed my shoes and ran the machine NO DISCHARGE. How do you put that in the manuel. As far as the dust collection issue, wrapping the outside of the hose is not enough, I noticed when the machine was running, and put my hand between the Z axis and the dust collection, I could feel the hair on my arm stand up. So after putting the wire thru the inside/outside that took care of that.
Thanks for all the input.

danhamm@abccom.bc.ca
10-16-2001, 06:09 PM
Yeh Jay,
I wear Nike's to, bin thar done that...especially
after moving around my little office with a little carpet on the cement..

papad
10-31-2001, 12:29 AM
jay and every one else, just my two cents on this as I didn't read this till just recently. On any vac system you have a large chance of fire or explosion potential the copper wire through the pvc pipe conected to the vac and the shop bot frame is at best the very least you should do the best is to run your duct work out of metal pipe and then any flex to have that the shortest possible and then run the copper wire inside that. Make sure that the vac and the shop bot are grounded to each other and then if possible run a secound ground wire to a grounding rod driven into the ground down at least 5' out side of the building. If this all sounds like over kill I'll tell you of my little jolt -- Working with a 1100 cfm vac 3 hp running a planer walked by touched pvc pipe duct with grounding wire inside etc. woke up about two min. later aprox. five feet away leaning against the wall that stoped my forward movement!! oh yea had to replace the fire extingusher after I put the fire out. I then did the research on what osha requires for factory setups. nuff said Dave

garbob
11-01-2001, 07:10 AM
Thanks Dave, we all need a wake up call once in a while!

Gary

Mayo
02-23-2002, 08:04 PM
Here's a grounding problem I have noticed. Perhaps someone can suggest a solution.

I realize this isn't the best way to have everything plugged in, but it's the only way I can do it for now.

My shopbot control box, computer and monitor and the dust pick-up shop vac are plugged into a surge protector strip. This surge protector strip is plugged into a 100' extension cord that is plugged into ANOTHER surge protector strip which has ANOTHER computer, monitor, printer, and network hub plugged into it, and it's plugged into the wall.

I have ANOTHER shop vac that I use for general shop clean up. It's plugged into the first surge protector mentioned above but I never use it at the same time as the other shop vac.

Believe it or not, this doesn't blow any fuses.
The router itself is plugged into a separate circuit.

The general use shop vac is creating a static charge problem. When I'm vacuuming up the floor or the ShopBot table and the hose is near the X rails, I can hear at least one stepper motor making intermittant step noises. The plug from the shop vac is not a 3-prong plug - it came with just a regular polarized two prong plug.

Is there a way to remedy this without putting additional electrical outlets in the room with the ShopBot? Can I somehow ground that shop vac or prevent the static from affecting the stepper motors?

I have the ShopBot frame grounded and the control box grounded with separate wires, to separate grounds. The control box grounds to electrical conduit in the wall and the ShopBot frame grounds to the copper water pipe that is connected to a grounding rod outdoors.

kaaboom_99
02-24-2002, 12:10 AM
The problem is typical of any vacuuming system that move a large quantity of air/material. Industrial units that vacuum with large hoses (as in our shop - 3"-5" hoses), the hoses themselves have a groundwire incorporated within the corrigation of the hose, due to the static charge that can build is enough to knock you to the floor. I suggest: Run a STRANDED(for flexability) bare copper wire along the outside of the vacuum hose, tape this wire at several locations along the hose, directly to the hose so that there is good contact and ground it either to a waterpipe or to the center screw on the plug plate nearest you.
Hope this helps.

gerald_d
02-24-2002, 02:18 AM
Hi Mayo, I agree with Perry. In our case we ran a bare copper wire inside the vacuum pipe, only because we thought that it would look better than a taped wire to the outside.

steve
02-24-2002, 12:25 PM
Hi Mayo, I machine a lot of mdf and the dust pickup is (was) made of plexiglass with a pvc tube attached that goes to a strong vacuum,I had noticed small amounts of static but one day heard a loud crack and saw a spark jump back to the router and it blew up my control board! despite the steel table being grounded to the mains.
Thankfully shopbot being the great company that they are I had a new board delivered here in the UK five days later, not wanting a reocurence I bought a grounding rod (10mm solid copper bar 1 meter long and sunk it into the ground about 3 meters from the shopbot and connected it with 10mm stranded copper earth cable direct to the steel table. I then made an attachment to fit to one of the crossrails of the y gantry and replaced the plastic tube with an inch and a half copper tube onto which I fitted a plexiglass bottom made in three pieces so that it only vacuums around the router cutter (unlike the sb one that vacuums the complete area below it).
I then made a round ring of the soft copper wire and soldered it so it sits inside the dust collection entry point around the cutter, with its tail going up inside the copper tube soldered to the wall internally, then soldered a copper tag on the outside of the tube and took a 10mm earth lead back to the connection point on the steel table. With an earth lead inside the vacuum connection tubes problem solved no more static buildup.
ps if you want pictures I can photograph and post here or email to you.

Mayo
02-28-2002, 02:28 AM
I'm wondering if I remove the electrical cord from the shopvac and replace it with a 3-prong grounded cord if this would solve the problem?


I haven't looked at the connections yet to see if there is a place to attach a ground wire to the motor.

Thank you all for the suggestions!

gerald_d
02-28-2002, 01:59 PM
There is a very good chance that it would solve the problem - certainly shouldn't make anything worse. But you really want to lengthen that wire along the suction hose as well (after trying to find some metal at the motor).

Going along the inside of the hose is quite easy and is directly where the source of the problem is located (friction on the inner surface). In our case it is a single bare copper strand about 1.5mm thick.

A thicker wire (lightning conductor size) is not necessary. The thin wire will continuously drain the static electricity and it is actually quite a low current. If you allow the charge to build up and then want to drain it away very suddenly, then you need the thick wires and rods.

jay.mack@chiefind.com
07-30-2003, 04:42 PM
Grounding...

Would this be a good way?

Drill a 9/16" hole through the floor in my garage, drive a 6'-0" grounding rod down through the floor and attach my wire to that?

StickMan

gerald_d
07-30-2003, 04:48 PM
No. Don't take the word "grounding" so literally. Connect to existing "ground" connections in the electrical circuits. You don't want "ground loops" - i.e. alternative paths to ground.

kerrazy
07-30-2003, 08:06 PM
Ensure your dust collector is grounded as well, as the tubing running to your bot. Your Control box will thank you.

gerald_d
07-31-2003, 03:00 AM
Here (http://www.siber-sonic.com/broadcast/GLoopFix.html) is an article that will keep some of you guys awake.






(For the guys who wonder how to make these hyperlinks - I actually typed in the following:

\link{http://www.siber-sonic.com/broadcast/GLoopFix.html,Here} is an article . . . . .

Notice the comma - left of the comma is the URL, right of the comma is the word that appears on the screen. No spaces anywhere before the comma. And it must be a backslash.)

jay_mack1@hotmail.com
11-06-2003, 12:54 PM
Gerald_D and Brady,

Here is a question I've got:

1. Grounding the frame, drill a small hole in the x-rail, drive a steel screw with a wire coupler on the end, connected to another that goes to the control box and then to a ground.

Can I run that ground wire to an outlet, use a plug and connect only the ground post to that wire and plug it into an outlet or should I run it to the panel box and attach to the ground bar there?

gerald_d
11-06-2003, 01:39 PM
Stickman, I think that you should not run any wire from the stud on the back of the control box to another ground point. The mains lead that feeds the control box contains a ground wire that will connect the whole control box case to ground as soon as you plug in that lead.

I think that you must concentrate more on the SB table end - grounding only one x-rail is far too little. Recommend that you put ground leads between each of the following items:

- router to vertically moving z-slide
- vertically moving z-slide to y-car
- y-car to gantry
- gantry to back x-rail
- front x-rail to back x-rail (because you have a wooden table)
- back x-rail to stud on back of control box.
Stop there - that is enough.

jay_mack1@hotmail.com
11-06-2003, 02:12 PM
Gerald,

Thanks for your help? What does a ticket to South Africa run? I might want to visit one day?

Jay

gerald_d
11-06-2003, 02:42 PM
Anybody else for a ShopBot "Safari"?

jkforney
11-07-2003, 09:42 AM
Gerald
Remember the airfare was too much for you to come to Camp Shopbots. Is it cheaper going the other way? Or is this something my wife will say "not no but hell no".

John Forney

gerald_d
11-07-2003, 12:13 PM
Hi John


We have to talk in relation to our income. You guys earn the mighty dollar, we earn the humble Rand. It takes seven of our rands to buy only one of your dollars. Which means that you will find a ShopBot Safari to be be cheap in terms of food, accommodation, etc. Look at these menus (http://www.spur.co.za/menu/adults.aspx) and divide by 7 to get the dollar prices.

noah@noahsart.co.nz
11-18-2003, 04:21 PM
Hi Everyone
I have noticed that a small spark jumps from the router body (porter Cable) to the pvc tube of my dust extraction system every few seconds when cutting. i THINK i have grounded everything properly, the Zzero routine works fine. I have a four-inch dust removal pipe, and I took the precaution of running a bare copper wire down the inside of the pipes all the way back to the cyclone,then on to the fan, grounded to the shopbot.
My final ground goes into the earth socket of the mains.
So why the spark? Am I missing some basic connection? Otherwise it wouldnt jump the half-inch to the PVC tube. Would it?
Simon

kerrazy
11-18-2003, 04:27 PM
The problem is the PCV pipe, replace it with corugated pipe. It really conducts electricity

jay_mack1@hotmail.com
11-18-2003, 04:40 PM
Dale,

Corrugated dust collecting pipe, Vinyl Covered?

What about a shopvac tube?

Jay

kerrazy
11-18-2003, 04:47 PM
NO it is galvanized metal, not plastic at all. The PVC actually accelerates a charge when wood dust passes by it. It can be very volatile and I would recomend removing it any wood working operation.

So long as your hose from your Dust skirt is hooked up to a metal pipe it will act as a spark arrest and prevent any hiccups.

SO they say adn my system seems fine.. no sparks seen yet
Dale

coastal
11-18-2003, 08:23 PM
I had a problem with stactic from my dust colletor. I solved the problem by grounding the pipe and dust hose. Rap bare copper wire around the hose and the pipe connect the other end to gound. Rockler sells a dust collection grounding kit for $11.99. It is just 50’ of bare copper wire with some clamps

jay_mack1@hotmail.com
11-19-2003, 08:14 AM
I'm working on creating my dust collecting system. I was going to use a tube for a shopvac, the one of the extentions to run from the dust collecting shoe to where the 2 1/2" line would run over the cable run. That would connect to a 4" line that will run to my dust collector. I was planning on running a bare copper wire throughout the whole line, back to the dust collecter and ground it out.

For the dust collecter skirt, I found a material at a hobby store. Its a foam material, about an 1/8" thick. I plan on cutting it about 1 1/2 to 2" in width and then cutting slits every 3/4" of an inch, applying two layers, overlapping the slits. (modeling it off our MasterWood head)

Any comments on my plans. I am still looking to see if I can find a 2 1/2" metal tube, to run from the dust collecting boot to the flexible tubing.

coastal
11-19-2003, 01:05 PM
The copper wire will need to rap around the hose. I tried to run the wire stright in some sections but the static would build up any where the wire did not go around the hose.

noah@noahsart.co.nz
11-19-2003, 03:38 PM
A couple of people have emailed me for a pic of a four inch dust collector so here it is. Hope it loads properly.
The dust collector has no skirt, but this does not seem to be a problem because of the powerful suction of the 4 inch pipe. It leads through a cyclone to a dust extractor.
The base of the foot has a circular inlet around the business end of the router, it is not open for the complete oval.

noah@noahsart.co.nz
11-19-2003, 05:44 PM
Apologies for that. Didnt work. The program said the file was too large, ie over 28kb, so I have to take it back into Photoshop and save it as a smaller file. I will do that later on.

Simon

noah@noahsart.co.nz
11-19-2003, 08:33 PM
Here is another try:

noah@noahsart.co.nz
11-19-2003, 08:49 PM
final try...

3762

noah@noahsart.co.nz
11-19-2003, 08:50 PM
Hurrah! There must be an easier way....

Simon

wayneo
01-12-2004, 06:14 PM
Has anyone tried using "conductive" flexible vacuum hose rather than a wire?

Seems like a good thing to do.....

jamesgilliam
01-13-2004, 10:55 AM
Funny I have not had the problem of static building up. I have 2" pvc pipe for the tube connected to 2" hot tub flex hose going to my dust collecter. After seeing the post about the sparks from the tube to the router I started watching for the discharge. Even turned off the lights for a couple of minutes and nothing. Only thing I can think of is I may be grounded through the bracket that supports the collection tube to the Y carriage.

K Simmerer (Unregistered Guest)
01-13-2004, 11:19 PM
All this talk of driving a seperate ground rod into the ground for your shopbot reminds me of a funny story about SINGLE POINT BONDING of utilities which is code in most areas. The story starts out with a lightning strike to one utility, lets say your phone line, then produces a powerful surge that jumps to a different utility that was bonded (grounded) at a seperate point (lets say that shopbot ground wire) by a phenomenon called differential looping. Now we've not only fried our shopbot (hmmmm.... wonder why the surge protector didn't even flip??) but charged up your AC lines to wreak havoc on your computers, tv's, video games.... you name it. Kind of sneaks in the back door. But we don't have building codes because they give a hoot about your TV. Safety issues like fire and electrocution are more pressing reasons for these laws. I'm not an expert on electricity or lightning strikes, but maybe consulting with an expert that is, (that would NOT be the guy who installed your cable or telephone lines) before you drive that shiney new ground rod into the ground and wire it up to something would be a good thing to consider. I spent a few days researching this subject and found it VERY enLIGHTNING.

Sorry for the bad pun. How about it, any electrical engineers out there have an opinion?

What is the proper or safest grounding point for your shopbot?

How about it Shopbot? Do you guys have an opinion on this?

Keith Simmerer

kivimagi
05-26-2004, 09:21 PM
I'm approaching this decision of how to ground things now. Some people say to put a rod in the ground some don't. I'm not sure how you can take the static out without it??

Would it be reasonable to bring my ground into the junction box, and then ground each outlet? Therefore everything should be on the same ground path?


It also seems very un-realistic to expect lighting to go back up your grounding rod.(Not that it couldn't happen, but there must be easier paths for it to dissipate.

Any thoughts?

weslambe
05-26-2004, 11:46 PM
I grounded mine directly to my ground on my breaker box which, in turn, I had to have grounded with a 6ft copper rod by the electric company's rules. So, in effect, I am running a ground straight to a rod 6ft in the ground.

I used to have static issues especially in dust collection. Not anymore.

Wes

gerald_d
05-27-2004, 01:31 AM
Maybe it will be clearer if you start from the "other" end, and work back to the SB......

What I mean is, start from where the power from your utility company enters your property, and look there for a ground connection. There should be a wire/strap running to/from a metal rod/pipe in the ground at that point. In our language, there should be 3 clear "circuits" at this connection point: Live, Neutral and Ground. The first two, Live and Neutral, arrive at your property inside insulation. But the Ground from the utility company is normally connected to a buried rod/pipe at your property as well. (If you have 3phase power, you will have 3xLives, 1xNeutral, 1xGround)

Then see how the 3 "circuits" (L,N,G) are distributed to to the power outlets near your SB. For this thread, check particularly if you have a clear Ground circuit running from your utilities connection point.

In my limited (one SB only) experience, connecting all the SB grounds to the "utility provider" ground has been sufficient. In some of my other experiences on ships/subs, the emphasis was on single grounding points to prevent ground loops, and this tells me to use a single rod at your property that has probably been installed by the utility company already.

kivimagi
05-27-2004, 02:25 PM
Thanks!

dbrown@mtn-state.com
05-27-2004, 10:41 PM
Ryan/Gerald

Here in the states the electric companies bring Three Leads to your house (single phase) 2 Hots and a Neutral lead (or center tap). The ground is attached too the neutral lead at the house and ran to the Ground rod or rods (I believe most power companies require two rods 6 feet apart and wired together).

Trying to run a seperate rod for the bot could produce a ground loop (Gerald is right) you must use the same ground rod as does the incoming service.

The other part of the equation is static, as stated above the vacume hose is a big contribitor to this problem. First off I would not run the hose on the wire hoop, this would help to keep static away from stepper wiring. Also as stated above I would run grounding through the hose to drain the static charge that builds up on the hose.

Be careful if you grease your rails, this grease should be conductive or you may break continuity between the X and Y bridges.

Don't forget to ground the control box case as well.

Dan Brown

ps I wear new balance

gerald_d
05-28-2004, 02:11 AM
Dan, interesting that the "states" is wired differently to Europe and most other places that I know. The 2x Hot was new to me, so you guys actually do have 240V available like the rest of us. This (http://hyperphysics.phy-astr.gsu.edu/hbase/electric/hsehld.html) was the source of my lesson that you triggered. How we have it (http://www.epanorama.net/documents/groundloop/feed_1phase.gif) - we get 230V and nothing else. At the bottom of this article (http://www.epanorama.net/documents/groundloop/electrical_wiring.html) is a conclusion on ground(earth) loops. A huge heap of info on ground loops. (http://www.epanorama.net/documents/groundloop/)

What about the grease inside the roller bearing, where there is more rolling contact? We physically put copper wiring across each of the v-rollers - drilled and tapped studs into each of the separate steel parts (z-slide, y-car, y-gantry, table) and connected a wire from one to the other.

dvanr
06-23-2005, 10:13 PM
Another interesting article on grounding and ground loops pertaining to computers communicating with CNC equipment. (nothing mentioned about static dissipation)

http://www.copper.org/applications/electrical/pq/casestudy/grounding.html

richards
06-23-2005, 10:34 PM
Dick,
That is a very interesting article, showing just how complicated connecting machines together can be. After I finished reading the article, I wondered why they decided to connect the machines together with any physical connection. That may seem to be a stupid question, but, to me, the obvious solution would have been to use either wireless connections or fiber-optic cable to connect the machines to the data source. Both of those methods should have eliminated the ground loop problem.

dvanr
06-23-2005, 11:31 PM
Hi Mike,

What works great in the R&D lab may be a challenge in the real world.


I have lost hair proving that too!!

richards
06-24-2005, 12:49 AM
Dick,
The reason that I asked the question is because sometimes thinking outside the box leads to a simpler solution. Amost forty years ago, when I spent two years in France, I could pick up the telephone and call my home in Utah. It was a simple matter of communications, similar to the RS-232 interface described in the article. If the telephone companies in France and the U.S. depended on having a common ground to solve differences in electrical potential, telephone communications would have been limited to a very small area. In the same manner, having all the machines in a factory connected to a common ground puts severe limits on the ability to add new machines to the factory. On the other hand, if the machines are distributed in independent cells with total electrical isolation between the cells, there can be no ground loop problem.

In my shop, I use that exact philosophy. The Alpha and the computer that controls it are in a cell separate from all other computers in the shop. The Alpha and its controlling computer are fed from a common electrical panel; but, communications between that cell and the rest of the shop are handled by a wireless connection. If the distance between the Alpha and the other fourteen computers in my little network was too great for wireless, I'd simply use a fiber-optic cable to connect the network together. It is basically the same system used by all of the telephone companies in the world that allows reliable communication between dissimilar equipment powered by a variety of different electrical systems to occur. In fact, since that time in France, I've talked to a son in Switzerland, another in Bulgaria, and another in Argentina as each spent two years working in Foreign countries. In every case, telephone communication was available.

Data communications in a computer network, whether it is in a factory or a telephone company, is still just basic transmitting and receiving of electrical pulses, with the spacing between pulses and the electrical potential of those pulses dependent on the protocol used by the various pieces of equipment. The telephone company uses as many different types of equipment and as many different protocols as is required to connect two telephones together; direct wire, fiber, microwave, etc. The basic action seems to be to first define the problem and then to solve it, preferably using the least complicated method.