Too much exhaust?

[James Jaragosky]

Today I connected a 5hp dust collection motor to my Rabbit laser to be used for smoke extraction.
First I had to enlarge the factory exhaust hole in the laser cabinet from 6in to 8in. Four foot of 8inch pipe and 4 elbows later and I am ready to test the new exhaust system out.
I tossed a 12 x 18 inch piece of warped 3mill Baltic birch on the 23 x 33 cutting bed and flip on the blower motor, Wow the birch straightened right out. I have so much suction now that I can hardly open the lid with the blower motor on.
Now I am a little worried that I may have too much suction.
Jim J.

[Rodne Gold]

You only have too much suction when the laser engraver casing implodes

[Dan Hintz]

FIVE HP?!!! Sheesh, I'm doing fine with the 1HP red unit from HF, and I'll be upgrading to a 2HP unit soon enough, but FIVE?!!! :P

[Mike Null]

There goes the air conditioning in the summer and heat in the winter.

[Randy Digby]

Afterburner...ON!

[Dan Hintz]

Not for me... I exhaust back into the room (after scrubbing, of course). No loss of heat/cold.

[Scott Challoner]

Be careful if you have an aluminum honeycomb table. I made some mods on mine for more suction underneath and now my grid is bowed. I have to put scraps of 1/2" Corian underneath to support it.

[Richard Rumancik]

Just a small point with this - people should not confuse high suction with high flow. James, you may have high suction, which is demonstrated by the fact that there is enough differential pressure to straighten the warped material. But suction does not mean flow. In fact, a traditional vacuum hold-down uses a lot of horsepower but the actual flow rate is not that large.

As an analogy, I can use a vacuum cleaner to lift of a heavy rubber ball. The vacuum cleaner is generating a lot of suction (differential pressure on the ball) but the actual flow is zero (as the hole is plugged). If there are leaks around the ball, I can generate both flow and suction.

If the 5 hp was used entirely to generate flow, then you might be able generate a flow approaching 1000+ cfm. But if that same flow is throttled (by enclosure impedance) and used to generate vacuum instead, the actual flow could be considerable smaller.

You might be in a situation that you can generate a lot of flow as well as create a pseudo-vacuum table. But it is normally a trade-off.

On some lasers the manufacturers have tried to accomplish what you are doing (creating a vacuum table as well as an exhaust system with the same blower.) But in my opinion it does not work very well for traditional exhaust systems (often less than 1 hp). You seem to have shown that at 5 hp the concept might work - but to be honest, not very many people would go to such a larger blower.

[Dan Hintz]

If the 5 hp was used entirely to generate flow, then you might be able generate a flow approaching 1000+ cfm. But if that same flow is throttled (by enclosure impedance) and used to generate vacuum instead, the actual flow could be considerable smaller.

As a point of reference... the DC2000B from PSI generates 1,000 CFM at 6" H20. And it's only a 2HP unit... strong little sucker (no pun intended).

[Anthony Scira]

Can not believe it has not been said yet !


YOU SUCK !


Just kidding, man that is a big fat pipe ! With that kind of airflow I would think you would be almost ok to cut some PVC materials.....but I know its still not recommended.

[James Jaragosky]

As a point of reference... the DC2000B from PSI generates 1,000 CFM at 6" H20. And it's only a 2HP unit... strong little sucker (no pun intended).

Here are the specs on the motor I used.

Specifications:
Motor: 5 HP, 220V, single-phase
Air suction capacity: 3961 CFM
Static pressure: 14.6"
Intake port with manifold: 4" x 4 Holes( I have 1 8" pipe)
Intake port without manifold: 10"
Impeller size: 15" balanced steel, curved fin
Collection bag capacity: 24 cubic feet( not in use)
Bottom bag material: plastic ( not in use)
Upper bag filtration: 2.5 micron ( not in use)
Machine collection capacity: minimum 4 machines
Detachable base
Overall dimensions: 74" W x 29" D x 134" H
Approximate shipping weight: 326 lbs.


I used the new extraction system this morning and it not only holds down material it removes all trace smells as well. That's with the lid open.

So far I am pleased with the new set up.
I can see a need to add an outside air intake to the cabinet.
And it is much nosier than my OEM blower.

[Chuck Stone]

I wonder if this is related to the article I just read..

[Dee Gallo]

CHUCK, YOU ARE HYSTERICAL!

dee

[Chuck Stone]

I'm early for an appointment ..I have too much free time!

[James Jaragosky]

I'm early for an appointment ..I have too much free time!

Thanks for the laugh
I may have moved into the Tim The Tool Time Taylor zone on this one.