Massive Static sparks in dust shoe

[mturneruk]

Hey chaps.




Yesterday i got a fairly big shock while adjusting my 3d printed dust shoe during a cut.

Since then i notice that every few minutes of cutting a fairly large spark seems to be jumping from the white shoe up the black collection pipe with an audible spark noise.

From what i have read this is static caused by the dust travelling up the pipe.

Question is what can i do to stop it, as i don't fancy getting another jolt like I did yesterday. Any way to earth this plastic pipe ?

Cheers
Martin

[Clive S]

Martin I have seen this before somewhere! I think the answer is to tape an un-insulated wire spiralled around the tube along its entire length and then earth that.

[cropwell]

Hi Martin,

Static is generated when the cutter pulls the material (like a Wimshurst machine). The charged particles travel up the tube and at some point have enough voltage to generate a spark. I would tackle this issue with some urgency as the spark could ignite the dust and cause an explosion in the dust collector. As Clive says, the best way is to provide a path to earth as soon as possible to get rid of any static build up. I would suggest that the collector pipe from the shoe to the flexible hose be replaced with an earthed metal tube, Aluminium would look good. Running an earthed bare wire up inside the flexible as well would help.

Looking at the rest of the machine, I would guess that you are justifiably proud of the aesthics of the design and build.

Cheers,

Rob

[mturneruk]

So I ran a bare wire from inside my dust shoe up to the top of the black tube in the picture and earthed it to the machine body which in turn is earthed. That seems to of solved my big spark problem. However I am thinking I need to run it all the way through my PVC ducting which is about 2 meters long. What do you reckon?

[cropwell]

You need to discharge the static, and what you have done is OK, but I would make that discharge wire longer to be sure. It is just a matter of surface area to make ground contact with the charged particles, that is why I suggested a piece of metal tubing.

Cheers,

Rob