Grounding flexible dust collection hose - questions

[aschutsky]

Hi guys,

I had my first lost communications yesterday (multiple times) after cutting 10+ projects, so now is time to address the DC grounding issue. I've ordered 50' of stranded copper to run inside of the hose. My com tests are scored in the low 80s so I'm assuming this has got to be my issue. Since I haven't seen any pictures of this implemented, I have a few questions:

1) Should the wire run entire length of the hose? If so, how are securing the end at the dust foot since it is not connected at that end?

2) Is it OK to tie into electrical ground (connects to grounding rod outside shop) at the end of the hose opposite of the machine? I have another 20' of PVC piping where the flexible hose connects, otherwise I would connect directly to the blower motor like normal.

3) Should I just drill a hole in the end of the flexible pipe at the end closest to the PVC piping for the copper wire to poke through and seal up with glue?

4) For those using blast gates and multiple connections - How are you running wire through these? Are you simply grounding each portion on it's own and hooking to a common ground?

My setup:
http://cdn.avsforum.com/c/cc/900x900px-LL-cc27417e_EA5FBF38-4838-4080-B7E2-79A1D5A0AD75_zpscg1l7azd.jpeg
http://www.avsforum.com/t/1428456/lightbox/post/24761626/id/438558

Thanks in advance guys.

[coryatjohn]

I would be checking your other possible reasons for static. Are all moving metal components wired to ground? That means anything that moves has to have its own connection. Connect all ground wires to a common point. Be sure that the ground to earth is solid.

The hose may be an issue but as far as I can tell, the hose grounding is more of a last chance thing than the first thing you should do.

[aschutsky]

I have seen this article:

http://shopbottools.com/ShopBotDocs/files/Grounding%20your%20tool%202012%2008%2007.pdf

Not ALL of my rails are grounded, but then again I have a PRT Alpha with steel rails if that makes any difference. The previous owner had no other ground connections other than the DC hose and had no issues for years. There is a fair amount of static in the DC hose as of now. The only other change I had made yesterday was changing the port my USB hub is plugged into.

From what I've read from Gary and Brady on here the hose is a very likely suspect and very common.

http://www.talkshopbot.com/forum/showpost.php?p=139197&postcount=3

[scottp55]

Andrew, I don't know if it's connected to your problem, but on both our Desktops we have problems unless we have USB connected to the same slot as SB3 was installed on. We've moved both machines a couple of times and problems go away when we use the original slot. Maybe just us.

[tri4sale]

I had comm issues as soon as I hooked up my DC. Ran copper wire thru the flex hose, at the ShopBot end I pulled out the hose and wrapped around the hose clamp to secure it, at the dust collector end I put small hole thru the plastic adapter and sealed the hole, and then connected wire to dust collector.

Not sure if this is the "correct" way to do it, but as soon as I did that I've had no further comm issues (knock on wood it stays that way)

And correct is in " " because what I've learned about grounding is that everyone has an opinion, and what works for one person does not work for another.

[coryatjohn]

>> Not ALL of my rails are grounded, but then again I have a PRT Alpha with steel rails if that makes any difference.

If it's not welded together it needs to be grounded with a copper wire.

That's my opinion anyway.

[jTr]

Andrew:

I fought this for the first two years of ownership of my machine. That experience has revealed it may be a number of issues combined. Since you're on the topic of grounding, follow it to the end, thus eliminating it from your checklist of what to do.

Copper ground wire almost eliminated the issue for me. In my case, I drilled a few small holes in the Kent dust shoe, and made a simple cross pattern of the bare copper wire, which acts as a stop for the larger particles as well as an anchor point for the spiral to travel inside the flex hose. Remainder of my DC system is 100% metal, so I simply terminated the copper wire at same point as the flex hose, and grounded to the metal duct by fastening the wire with a sheet metal screw. Per SB assembly guide, I've got a substantial grounding point on one leg of the Shopbot, where paint was scuffed off and a grounding terminal was fastened by the electrician.

Since you have lengths of PVC, you do need to make a grounding path to the dust collector housing, which in turn should have a grounding wire tracing directly back to your breaker box. Doing so through all of the duct is wise, as it will:
1> Establish a fully grounded system that not only will assure you that you've done all you can for the SB issue, but,
2> May also reduce static ignition fire hazard that many argue is present when utilizing PVC in this manner.

What was the single most effective thing I did to really, really eliminate the dreaded lost comm's issue?
Upgrade to latest version of control software. In my case, it exposed a few problems with my control computer trying to update unbeknownst to me (and contrary to the fact that all the proper update reminders were turned off in the user accounts settings of Win7 - keep an eye on that little flag indicating PC issues that need to be addressed on the right hand side of the start bar - you would not believe the rash of issues it caused!).
I really do like the updated features, such as the memory keys now available on the keypad.

Why would that help with communications? If you read up on the details:
Enables 2X+ faster communications and 7X more information buffered on Control Card:
Speed and buffering creates more robust communication between PC and Control Card.... This is specifically meant to target the problems you and I have experienced with lost comm's.

I have not lost communication since updating last month, and sincerely hope my experience helps you eliminate this issue - I feel your pain - (and hopefully no more!)

Best of luck,

Jeff

[tri4sale]

In my case, I drilled a few small holes in the Kent dust shoe, and made a simple cross pattern of the bare copper wire, which acts as a stop for the larger particles as well as an anchor point for the spiral to travel inside the flex hose.

Now thats a great idea, never would have thought of that, and thanks for the picture, I've printed it and will be doing something similar with my Kent dust shoe. Just hope I left enough slack down there to do this, else I'll be stranding some wire together.

[myxpykalix]

I just skimmed each article but you are supposed to ground both ends of your wire. One end to your carriage/dustshoe, wire goes thru pipe then other end gets attached to your dust collector. I've been doing it this way for 8 years now with no issues.

[coryatjohn]

Andrew:

I fought this for the first two years of ownership of my machine. That experience has revealed it may be a number of issues combined. Since you're on the topic of grounding, follow it to the end, thus eliminating it from your checklist of what to do.

Copper ground wire almost eliminated the issue for me. In my case, I drilled a few small holes in the Kent dust shoe, and made a simple cross pattern of the bare copper wire, which acts as a stop for the larger particles as well as an anchor point for the spiral to travel inside the flex hose. Remainder of my DC system is 100% metal, so I simply terminated the copper wire at same point as the flex hose, and grounded to the metal duct by fastening the wire with a sheet metal screw. Per SB assembly guide, I've got a substantial grounding point on one leg of the Shopbot, where paint was scuffed off and a grounding terminal was fastened by the electrician.

Since you have lengths of PVC, you do need to make a grounding path to the dust collector housing, which in turn should have a grounding wire tracing directly back to your breaker box. Doing so through all of the duct is wise, as it will:
1> Establish a fully grounded system that not only will assure you that you've done all you can for the SB issue, but,
2> May also reduce static ignition fire hazard that many argue is present when utilizing PVC in this manner.

What was the single most effective thing I did to really, really eliminate the dreaded lost comm's issue?
Upgrade to latest version of control software. In my case, it exposed a few problems with my control computer trying to update unbeknownst to me (and contrary to the fact that all the proper update reminders were turned off in the user accounts settings of Win7 - keep an eye on that little flag indicating PC issues that need to be addressed on the right hand side of the start bar - you would not believe the rash of issues it caused!).
I really do like the updated features, such as the memory keys now available on the keypad.

Why would that help with communications? If you read up on the details: This is specifically meant to target the problems you and I have experienced with lost comm's.

I have not lost communication since updating last month, and sincerely hope my experience helps you eliminate this issue - I feel your pain - (and hopefully no more!)

Best of luck,

Jeff

That's a great idea! I can't tell you how many items (like gloves!) have gone down that damn tube and into the barrel. I'm going to add that to my Kent shoe too.

[aschutsky]

All - Thanks for all the insight and ideas. The grounding should be very straightforward and I'll do that sometime later in the week. I'll at least do that as a starting point as well as add another solid ground to one of the table legs. It's interesting to see that some ground at the 'bot end and others strongly recommend against it.

Jeff - That's a neat idea with your grounding 'web.' :)

[jTr]

Since some of you are interested in trying this, I thought some additional views may be handy. If you have ideas to improve or enhance, please share.

Of note:
- 18 gauge copper wire was used- I'd discourage stranded cable, as debris hangs up in it.
- This woven wire will make the pickup hose a bit more snug when fitting back on the collar, so more effort and a variety of pliers should be close at hand.
- Tip I used from Brady for threading your wire through the flex hose - grab a cotton rag and attach to one end of the wire. With dust collector running, carefully feed the rag in, controlling the amount of wire length you need to reach the next joint in the duct. (It's really quite fun)

jeff

[aschutsky]

Jeff - Very nice tips and pictures, thanks much for posting. I'll be setting this up this coming weekend but not after I bust out a quick last minute fathers day gift. Hopefully I can hold off the gremlins until then. :)

[feinddj]

Dump the pvc immediately. chips pulled over pvc equals static. There is a reason that dust collection duct is made of metal. Not only does static charge spell trouble for your comm but it also can generate sparks. It is an extreme fire hazard. Small particulates can can fire with exceptional vigor. Just shake a cup with some non dairy creamer and then release over an open flame. In my locality, all dust collectors are to be inspected by the fire marshal, and pvc would fail immediately.

D

[POPS 64]

Andrew , David has the right idea . Pvc is bad news fires , static shock , and comm issues. I started with pvc and it didnt take long to make the dicision to switch and metal was actually cheaper to run . and haven't had any issues since.

[bcondon]

I have used PVC in my dust collection system and NEVER had a problem.

Let me explain

I have the exterior on the PVC wrapped with a stranded copper wire.
Additionally, I have an internal copper write running the length of my pipes.
Each end of the internal/external wires are connected by drilling a small hole through the pipe. Next the wires are connected directly to the dust collector.
The dust collector is grounded to the power panel.
My shopbot is grounded to the power panel
My metal controller box is bolted to the leg/end of the shopbot. Where the leg of the metal controller box attaches to the frame, I used a grinder to remove one square inch of paint (to shiny metal for my ground)
The ONLY time I have comm problems is when I use my finer stick in one of the USB ports and I click to remove it from the machine,,, sometimes I will get a comm error so I shut down the control software and restart it after removing the finger stick.


An important note is that I have NEVER had the machine on the internet and never had virus software. I simply design on a machine with virus protection and then transfer my cut files with a finger stick

For this model I am very deliberate at completing a design and know it is ready to cut

Had the same machine for 6 years with no upgrade and minimal troubles
IT JUST WORkS and no drama about upgrades.
I work 35 years in the computer industry and the major failure across EVERY company was the upgrade process....so I don't and there has not been a single thing that I needed that the good folk at Shopbot did not think of before 2008!

Bob condon

[feinddj]

Bob,

That seems like an awful lot of work to ground out something which will inherently build static. I do ground my flex hose inside and out for that reason. I use as little of it as possible due to the loss of air movement with it. PVC does not move air like steel. I went for the nordfab stuff so that I would not have any issues and get the most out of my dust collection with the least issues. Given the cost difference of ordinary metal duct vrs pvc that you will have to modify extensively, metal is a much better choice.

David

[knight_toolworks]

it is easier to use flex hose with wire. I just strip the ends and solder w wire to it for ground. having wire in the hose caused wood splinters to jam up.

[cr2]

No doubt the Nordfab is nice stuff. Let's say you have 100 feet of pipe to run. The cheap Nordfab (galvanized instead of stainless) is $25 per 5 feet so the cost for 100 ft. is $500. Thin wall pvc sewer pipe is $8 per 10 foot stick...so that's $80 for the same 100 ft. Then you've got to buy a bunch of fittings at either $5 ea. for pvc or $30 each for Nordfab. Let's be conservative and say 10 fittings. That brings the total price to $800/Nordfab or $130/PVC. It's easy to see why people choose to do a little static management on PVC. Of course these numbers are an approximation for demonstration. If you have links for better prices for Nordfab, please post them.

I've been using pvc for over 30 years without any static problems. It's not glued together so I can rearrange it at any time.

[gundog]

Oneida sells metal duct work and has all the fittings you need and 4" x 60" duct runs $15 not as cheap as PVC but it is designed for this application.

[bcondon]

So my situation was that I was pouring a foundation for the shopbot room (18 x 24) and a adjoining foundation for the refurb in the house which was
24x50 to contain the shop. The challenge was that I had to run a couple pipes under the corner of the existing garage to get them connected.

The DC is located in a fireproof closet in the shopbot room.

It took me under a day to put in 3 drops around the shopbot room (flexibility because we did not know where the machines would go) and I put in 7 drips in the basement shop. All tools have a dedicated drop with gates and flexible connection.

My cost for gates, pipe, fittings and copper wire were under $200. The S10 control to wirelessly turn on the DC from an location (remember we are physically separated between the basement and the DC) was $50 which includes 2 control locations, FOB key, and the "appliance device - 240 VAC" which actually turns on the DC.

The cost of metal would have been probably $1000 + plus the challenges of getting the angles correct. The fittings in metal are brutally expensive and you need a ton of them.

Brady - if you do a neat job, the wood does not get caught up...

I would also refute the comment that the metal has a better flow over b over PVC. PVC is smooth and you can get street sweeps for elbows giving you better flow there (which is where the losses are)

I could also add separators at the DC and at the Shopbot to get the shavings before they hit the DC.

I will say there are two camps for Metal and PVC. I see a lot of people in the metal side wave their arms and yell fire when actually result, if you take a small amount of care to put in the ground wire and make dedicated connection, are inexpensive and from my mind, I KNOW that I have a good connection.

I have worked as an electrician so I understand grounding and power panels (I have 4 power panels in the house/shop/garage to distribute power).

Funny story with our last house, we had a separated garage with full woodworking shop in the gambrel second floor. I wanted to put a separate 200A panel in the garage (separate service) and I had a 200 A panel in the house. The town said ONLY ONE SERVICE PER PROPERTY so I said ok... we will pull 400 amps through the house... no problem.
The town electrical inspector has a fit and I told him I wanted it to be safe which is why I asked for 2 services... I got two services...

Oh well.

In the end I am very pleased with my setup. It works well, it is safe and I don't communication failures on the shopbot...

My DC is a Reliant 3HP system so it is a bit light for CFM (1250) but takes care of my needs...

Thanks
Bob Condon

[POPS 64]

Hi guys were I live pvc is high in price . When I decided to switch to metal I decided to try something different , I went to the home center bought heating ducts with adjustable elbows and used y's so everything was sweeping. And during and after assembly I double coated every seam and joint with the best seam sealer they had and it works great . The big test was with corian doing lithophanes when I finished the table and floor are as clean as when I started I was shocked . I run the main 3 branches with 4 drops all with blast gates. But for being on a budget I wouldnt replace with the good stuff . All in the sealing . Just do what makes you comfortable with and your budget long as it works and is safe. Good luck Jeff:)

[Kyle Stapleton]

PVC works fine, but you do have a problem with your setup. It looks like you have just 4" runs from the DC to all your tools which is very bad when it comes to getting the most out of your DC.
What size DC do you have and how large is the intake on it? If the intake is large then 4" you really should rethink you ducting, it may cost more money but it will be worth it. We fitted ours ( home shop) last year from all 4" to 8",7,6,5 and finally 4" at the tools and wow:)

[aschutsky]

Before designing and running all my DC piping, I did about 2 months of research. As a weekend hobbyist, I was concerned mainly about the most efficient setup (while remaining safe of course) I could build for the dollar. My budget was 500-600 including the dust foot. I went slightly over but not much.

My cheapo setup includes:

-About 30 feet of 4" PVC plumbing along with 7 blast gates
-Harbor freight "2HP" blower motor
-DIY Phil Thien baffle in metal trash can
-Filter delete and venting excess dust into woods through window
-Connection to CNC, floor sweep, 2 roaming 4" pickup tools, connection to radial arm saw
-2 x 10' flex hose for roaming pickup tools, 1 x 20' flex hose for CNC

My setup works quite well for my little part time shop. If I were running a full time shop, I'd for sure invest in 6" + metal piping and a much larger blower. I spent a TON of time reading about 'grounding' of the PVC setup. I could not find any instance where a dust collection system using PVC piping was definitively tied to a fire or explosion. I came across this interesting article through a recommendation which applies some physics to the subject:

https://home.comcast.net/~rodec/woodworking/articles/DC_myths.html

With that said, it's SO easy and inexpensive to run a grounding wire either through or around the piping (or both) to eliminate any threat of shock or issues with coms on the bot. I'm more concerned with the com issues than anything else at this point.

Back to the original topic - I had been playing around with my PC and I'm fairly confident this is more PC related than anything. My previous laptop had no issues with com loss, so I'll try another PC this weekend to see what's up before running all the grounding wire - which I'll do anyway but I want to find the root cause here.

[aschutsky]

Update: I've grounded everything now but also trying a new PC for the bot (laptop). Com efficiency has moved to 88% or so and NO issues running a few projects through it. :)