Dust collection wizards...

[Jay Caughron]

we will find out,, right now its temporary and can be changed if needed.. well we gave it a good test last night and it works great.. tom even was impressed by how much better it was..

Glad to hear Larry I knew it would work.......

[larry merlau]

Glad to hear Larry I knew it would work.......

yeah jay when i got it hooked up you could hear the differnce.. tom commented that it was louder as well.. thanks for the help

[Jay Caughron]

Glad to be able to do it Larry

[Chuck Ellis]

When I took mine apart to measure it from morbid curiosity there was a fairly good sized gap between the impeller and the housing (I didn't measure it but it was decent sized) so I wouldn't take the impeller housing as any guidance on the size of the impeller itself (I've heard rumors that the Rikon 2HP with is supposed to actually be a 12" wheel actually fits - I had a hard time figuring the $$ value vs another used impeller assembly as far as doing a replacement).



Turning and sanding are both a PAIN even more on the collection side than the DC side so I feel your pain there.

I'll second Vaughn's question on the filter.. Moving to a Wynn 35a filter helped a LOT with the airflow (more sq feet, less restriction) and residual dust. I used the stock filter bags for about an hour of testing so I don't have a good feel for the long term dustiness....

Sorry, haven't been back here for a couple of days, so missed your questions...

I used the original bags for a while, but a couple of winters back, varmints got into my DC shed and decided even with the dust, the bags would make good nesting material or I had chips that flew into the sides and made holes... but I replaced them with a felt type bag I got off line... that must have made even better nesting material... I opened the shed to check on why I wasn't getting much draw and discovered I had huge holes in my bags and dust an inch thick in the shed... I replaced them with better bags I got on line and don't have quite as much dust in the shed.... I have my DC installed in a shed outside the shop and plumbed through the wall, so I could cut down on the noise and any dust coming through the bags, but I'm still not drawing all the dust off the lathe when I sand...

[Bill Nicklaus]

DC is more than just CFMs, clearly the volume of air your unit can move will dictate how large a "system" of pipes you can use/run and still COLLECT DUST. And Dust Collection (the real goal) is more important than chips. To collect dust - it MUST remain suspended so it can be moved through your pipes into a collection bag. This little bit of magic requires VELOCITY. In order to keep dust suspended it must travel at or near 4000 feet per minute, or it will not make the run. Each foot of pipe regardless of size (don't get me wrong size affects velocity) creates resistance that slows the rate of air flow. This seems to be a nagging problem for fellow woodworkers so I will try to find my notes and see if I might be able to help. It means calculating the volume of air in the active (the ones connected to the tool(s) in use) pipes and the effect of every bend as well. Maybe I am making this too involved - does anyone really care about the physics of all this - - - IF so I will work on it. BILL

[larry merlau]

well bill, i think i got my problem fixed, but i do have a question for you.. the speed at which air is leaving my outlet pipe, does that represent the inlet speed or could inlet be less ? i dont use a bag it goes directly out side.

[Ryan Mooney]

well bill, i think i got my problem fixed, but i do have a question for you.. the speed at which air is leaving my outlet pipe, does that represent the inlet speed or could inlet be less ? i dont use a bag it goes directly out side.

Physics claims that if the pipes are the same size and there are no leaks in the inlet system they should be darn close (ignoring turbulence, etc.. which would probably have marginal impact, although fluid dynamics is complicated so I reserve the right to be wrong). Practically speaking the two caveats I added could affect the real world results, as could the other factors that I'm thinking probably don't matter (but could).

If your outlet is a reasonable length of pipe (say 2'+ or so) it removes ~most of the chances of getting false readings due to turbulence or dead spots from weird exit airflow patterns (or simply move your measurement device around the opening and if it reads the same at multiple spots its probably ok )

[Bill Nicklaus]

Physics claims that if the pipes are the same size and there are no leaks in the inlet system they should be darn close (ignoring turbulence, etc.. which would probably have marginal impact, although fluid dynamics is complicated so I reserve the right to be wrong). Practically speaking the two caveats I added could affect the real world results, as could the other factors that I'm thinking probably don't matter (but could).

If your outlet is a reasonable length of pipe (say 2'+ or so) it removes ~most of the chances of getting false readings due to turbulence or dead spots from weird exit airflow patterns (or simply move your measurement device around the opening and if it reads the same at multiple spots its probably ok )

Larry, you brought up two new issues. First: discharging directly outside is usually a benefit since you have removed the pressure needed to push air through the micron filter bag. But - you now need to be careful about how long the discharge pipe run is as your impeller fan must now suck air and push air in the pipes. Second: As Ryan noted, if we ignore turbulence the air speeds would be close - however as he also points out real world results are never ideal. Your inlet air speed (the speed of the air after it reaches the fan) is dependent upon the vacuum power of your unit which will be restricted by length of travel, bends, joints, pipe interior friction (pvc will tend to accumulate a dust film and inc frictional resistance to air flow) and how closely matched available air volume movement is to your DC specs. You may have read other posts stating that opening another gate in their system actually increased the effectiveness of their DC - this is because the system was essentially choked with low air volume available to the unit. Outlet air speed is usually slower but should not be a problem unless the outside run is long. Fortunately we are only concerned with collecting some dust and not building a spaceship - so we really don't need to be so specific or worry too much about it. Collect some dust, but enjoy the woodworking!