How to work out losses in reducing HVLP extractors?

[wcndave]

Thanks, I tried a few readings yesterday on grounding. I found that with the multimeter set to "beep connection" mode, I had a connection between the motor on my drill press and the motor on my bandsaw.

I had none on the tables of those tools, and thought I had none on my planer and TS too, until I realised they were not plugged in. Doh. So once I did that I could see I have ground on the cast iron table of my TS, so I will attach my wire to that.

Hard to find twisted copper wire these days, I will get some speaker cable and take off the plastic.

Cheers!

 

[jimmy_s]

Might be difficult getting rid of static in the ducting if its all plastic (unless its a conductive plastic made for the job). The charge created by the wood chips and dust is not being dissipated. Spiral wound duct would be the obvious answer, you can then also get better formed branches (45 degree) and long radius bends etc. The Lindab safe system is good, and easy to work with if you ever decided to change your system.

Low Relative Humidity (40% and below) tends to cause more static problems with plastic ducts etc. RH levels up around 50% tends to dissipate static better presumably because the water vapour in the air improves the conductivity to a level where the static dissipates naturally.

 

[wcndave]

I have 10 degrees and 28% humidity in workshop, so definitely adds to it.

My 2.5" system is great with the vac, and with the same airflow from a "near stall" chip collector, I won't need to faff about with hooking the vac up all the time.

I have always noticed that it attracted dust, and there was clearly static, however it never bothered me, I never got shocked.

Getting shocked every 3 seconds is something else though.

I use mostly spiral wound, as the long straight run is under the concrete. I think wound wire will dissipate it fine. Right now it's building up charge, looking for a path, and going through me (seems to build up to a high enough charge to do that in just 3 seconds). I am sure if I offer it up a nice copper wire going straight to ground, it will love that, and leave me alone.

I will try first with the wire that's in the spiral, see if I can expose it and connect it to the underside of the TS somehow.

 

[jimmy_s]

Sorry - I thought it must be plastic duct - if you cross bond the galvanized spiral wound to a the table saw or similar then that should sort it out.

 

[wcndave]

Oh I do have a lot of plastic duct, the 2.5" system is all plastic, and the 4m underground pipe for the 4" is plastic, plus lots of plastic connectors... Ah wait, you mean spiral wound like the metal ducting... no I mean the flexible plastic pipe that has a spiral of wire in it... I got my terminology confused...