Grounding flexible dust collection hose - questions

[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.