And still another silly question about vacuum

[jbworden]

Not to imply that all the other questions about vacumm were silly but this one may very well be.

I have this nice big cyclone dust collector (okay it's only 1 1/2 hp but it looks big) whose only purpose in life is to collect the dust from my Shopbot's router. According to Grizzly's specs it pulls 1025 CFM @ 2.5" SP (I have no idea what 2.5" SP means) and max static pressure is 10.3" if water. SInce I have no plans to use this for anything other than it's current purpose would it be reasonable to try using this thing instead of the Fein's to supply the vacumm for hold down.

Am I so far out in left field I'll never find my way back on this one?

[searayx350]

Depending on what you are holding…

I have an industrial vac pump but I also have a dust collector with a modified rotor that works well. An entire 4x8 table as a matter of fact.

The biggest issue with a dust collector is to keep the movement of air from collapsing on itself. I will post later today with photos and full details so please stand by.


Thanks,
Josh

[searayx350]

Ok, to better answer your question,

I use a setup of dual dust collectors to keep the air from collapsing. I also modified the rotor to help the situation.
If your dc has curved fins you WILL HAVE TO MODIFY it. If the fins are straight you are ok.

you will need run the intake of dc 1 to the plumbing for the hold down and you will need to put another dc or shop vac’ s intake on the exhaust of dc #1. This will keep the air from collapsing on itself.

True vac pumps have segmented chambers the intake and exhaust and this avoids compression or collapse.

I am also designing a mod plan to allow similar results with a dc without having to run a dual system.

You can go to http://www.jscustomwood.com/jim/vac.asp to see the photos.

[andre]

Ok you mean to tell me you are using a dustcollecter as you vac hold down? How is the motor not burning out or tripping the circuit?
I just ordered two feins for my new prs. How long have you been using this setup?

[searayx350]

For 6 months or so. This was a band aid but worked so well I kept it. I have the commercial pump on my Accu-router.
Avoiding compression or air collapse is the key. That’s why I add suction to the exhaust. This thing doesn’t sound strained or run hot. According to the amp meter the current draw is as specified on the nameplate.
I am an engineer by trade and I assure you this setup is ok.

It holds a 4x8 sheet of MDF like a charm. I use a roller hold down that is attached to my modified gantry for ply’s.


JM

[searayx350]

I wanted to let everyone know that I am only illustrating that it is possible. A major factor is your plenum.

I use a 1” thick HDPE plenum (cutting board material) that does NOT leak. I also route a grove in the plenum around the zones and perimeter and put a rubber gasket that protrudes about 1/32nd and I PVC edge band the spoil board so I have a pretty efficient setup to begin with and can get by with less vac…

Josh