Dust Collection Causing Comm Errors

[DanThomson]

Let me start with a little of the back story leading up to this...
I purchased my machine last summer and battled comm errors until, with the help of people on this board and especially Gary Campbell I traced the comm errors to improper grounding.
I have since grounded the machine as per Gary's shopbotwiki article as well as running a 12 gauge bare copper wire from the dust shoe through the DC hose and up and out to a ground wire running back to the electrical panel.

I have been comm error free since about August when just recently I got a 12hr job 3D machining parts out of laminated 3/4" MDF. When starting the job I was running into various comm errors, I decided I would eliminate the possibility of static buildup from the DC by removing it from the equation. After doing so I did not have a single comm error in the remaining 11 hrs of machining. However I was also left with a disastrous mess of MDF dust coating everything in the shop!

I would like to solve this issue so that I can prevent this type of mess in the future. I have attached a few photos of my setup in hopes that someone can shed some light on where my grounding problem may lie.

As always any help/info is greatly appreciated.
-Dan

[srwtlc]

How about the internal/integral wire in the hose itself. Is it tied to the 12 gauge wire also? MDF dust in large quantities can build up a lot of static.

[feinddj]

I got the Kent dust shoe and had problems with static. I grounded the duct and later added a wire right to the plex of the shoe. If problems develop after that, check your computer. Mine, apparently, did not like the static either and said good bye cruel world. Got a new laptop for 350 bucks and no problems.

David

[garyc]

Don...
A few things to check, verify or try:

Continuity on the ground that goes thru the DC hose and connected to the dustfoot.
Make sure that the Z extrusion is grounded.
Watch the location of the ZZero plate and its ground clip. When the gantry moves back and forth, static built up in/on the DC hose can discharge direct to them.
Clean the inside of the dustfoot and install a layer of tin tape. Try to get continuity to the ground wire.

An old wives tale: Dish soap & water (50/50) in a spray bottle sprayed up the dust hose will make the inside surfaces a conductor temporarily. Also allows MDF dust to REALLY stick!

Good job on removing the DC from the equation to isolate it as the cause of the problem.

[gc3]

i would wrap that wire around the outside of the hose rather than the inside and attach the internal wire to the same

[DanThomson]

Thanks for all the responses, to answer some questions:
-I do not have the internal wire of the DC hose grounded because I was under the impression that running the bare ground through the hose bypassed the need for the internal hose ground, are both necessary?.

-Gary, I do not have the Z extrusion directly grounded but I do have a ground running from the spindle mounting plate, would you still recommend grounding the Z extrusion as well?

I am considering zip tying a bare ground wire to the top of the inside of the dust shoe and connecting that to the bare wire inside the DC hose, any thoughts?

[garyc]

Dan...
I was speaking of your bare internal, not the integral (encapsulated) wire. Having them both connected can do no harm, and may help, so test both ways.

If the spindle mounting plate is grounded AND you are sure of low impedance contiuity, then that should work. Is the Y car grounded? Have you verified that all connections are good and there is actual continuity to the panel ground lug?

Any plastic part that has air movement over it can generate static. Some more than others. Adding dust to the air increases the static potential. Some materials, especially MDF fibers or plastic are worse than others.

Adhering tin tape to the inside of the dust foot will make it a conductor. (inside) Static will not build on a conductor.

Static discharge is a problem in most low humidity seasons or areas. Conductive hose is available : http://www.flexaust.com/static-conductive-hose

[dana_swift]

One idea I have had (but not needed (yet)) is to put something in the dust collection system to make very turbulent flow for a short section which would be made of metal.. so the particles inside would be very likely to come in contact with the metal and discharge the static held by the inner particles. These could be placed periodically in a long hose to reduce the static charge.

If a particle in the dust air does not contact a conductor it cannot discharge because air is a good insulator.

I really like the conductive hose, that may be a huge improvement where hose is needed. I have used non-conductive/non-grounded hoses for hand cleaning and have had the **** shocked out of me when the static decides I am the best path to ground.

Gary- thanks for the link.

D

[signsbyjay]

Dan,

It is hard to tell from the pictures, but does your ground wire extend all the way into your dust foot, or stop where the hose attaches to the top of the dust foot? I ran my ground wire ALL the way to the bottom of my dust foot and around the bottom of the foot and terminated it to the outside of the foot. That stopped my static problems.

Jay

[mike_greschuk]

Out of curiosity where do you ground your internal wire to when you have a kent dust shoe installed???:confused:

[gc3]

http://www.staticelimination.com/index.html