Got some nice coverage on Woodgears.ca

[phil (admin)]

Got some nice coverage on the woodgears.ca site (IMO).

It may have been more helpful had he not been testing the unit with his own shop vac, or at least made some comparisons between his shop vac and commercial shop vac first.  I don't know how his home-made vac compares to a large unit from Ridgid, Sears, or real Shop-Vac.  There is one point where he covers the inlet of his separator with his hand and has little problem removing his hand.  This is in stark contrast to me sticking my hand over the inlet of my unit.

I know I use my unit for my planer and wide boards and it works pretty well.  And I have my 2.5" pipe network and a bunch of blast gates in the mix, too.  Not perfect, but perfectly usable.

And I'm a bit surprised he didn't extend his outlet tube further, seeing as he extended the depth of his separator.

But still I think the video showing that the separator was able to remove more flour from the airstream than the 3M filter he was using was pretty impressive.

And I was overall very happy with his impartial testing.

I think it would be interesting for him to compare an off the shelf plastic cyclone with one of my units.  But I'd prefer that he use a shop vac like most everyone else would.

I'm not saying my unit is going to beat a conventional cyclone.  I just think it would be interesting to see some impartial testing.

Oh, here is the site, for anyone interested:

http://www.woodgears.ca

[aqengineer]

It seems to me that he designed his own blower that isn't a good match for a separator.  A typical shopvac moves few CFM but at high pressure.  A DC blower moves a lot of CFM but at low pressure.  His blower seems to move few CFM but at low pressure.  He would probably have been better off using larger fittings and not restricting the inlet of his separator, because I think that is all his blower can handle.  A quiet blower that uses little power and couples to a separator while still having enough suction to help with shop tasks is a pretty tall order.

Phil, did you ever do any testing on your units to determine what kind of effect they had on CFM?

[phil (admin)]

It seems to me that he designed his own blower that isn't a good match for a separator.  A typical shopvac moves few CFM but at high pressure.  A DC blower moves a lot of CFM but at low pressure.  His blower seems to move few CFM but at low pressure.  He would probably have been better off using larger fittings and not restricting the inlet of his separator, because I think that is all his blower can handle.  A quiet blower that uses little power and couples to a separator while still having enough suction to help with shop tasks is a pretty tall order.

Phil, did you ever do any testing on your units to determine what kind of effect they had on CFM?

Yes.  Although I didn't use a shop-made manometer because I was concerned that with the power of the shop vac, I'd have to either make an awfully large instrument, or risk getting colored water all over the place.  I don't know if the specs are baloney or what, but some of these vacs claim well over six feet of lift!

Instead I used a weather-vane type anemometer.  A good one, made by Kestrel.  They claim you can trace their calibrations back to NIST.  For relative measurements, they should be good enough.

When I first started using the anemometer, I discovered that it couldn't really handle the speed in a 2.5" hose.  So for my readings, I used a 2.5" to 4" adapter, and a 12" (approx.) section of 4" pipe.  This allowed me to get pretty accurate readings of airspeed, and I was able to compute CFM.  It was a pretty decent way to get some relative measurements (that is, without separator, and with separator).

I have a spreadsheet that I hosed at some point.  I'll duplicate the tests in the next few days.  Not a bad idea anyhow, as I'm now using a larger separator (based on a 30-gallon drum) than before.

[phil (admin)]

First, a pic of the two separators I tested.  The rear (larger) one is the unit I currently use.  It is using a 30-gallon plastic drum which doesn't seem to have too many problems w/ static.  I don't know if it is the type of plastic, or what.  The smaller one in the foreground is a 10-gallon steel trash can I no longer use.  Both of these separators use top inlet (with elbow), and the #'s I got from my tests (below) were almost identical.  The shop vac is a larger Ridgid unit (one of the magical 6-HP types).

The 2nd pic shows the weather-vane type anemometer from Kestrel.  It is a good unit, they claim they can trace their calibration back to NIST.  But it can't handle the air speeds from a shop vac, so I use a piece of 4" PVC and a 2.5" adapter (below) to essentially make an adapter that reduces the air speed.  Not a perfect solution, but I'm making relative comparisons mostly.

The 3rd pic demonstrates how I take a reading of air speed of air going INTO the smaller separator.  I basically take a center reading, and then try to find an average reading around the edges of the pipe.

The 4th picture sort of gives you an idea of how the separator is connected to the shop.  The separator, along with the vac, are in the back corner, and controlled with a remote I keep with me.  There is a network of clear 2.5" pipe, and blast gates, that brings the collection to each of my tools.  For example, the two bandsaws (one configured for resaw, one of curves) each have their own blast gate.

In the next two pics, you can see one of the compromises I had to make in order to get the DC piping up and over and around a beam.  Having extra ribbed hose isn't the greatest solution.  Maybe someday I'll figure out another way.  In the 2nd pic you can also see the mounting bracket I made that holds two Dylos meters, basically accomplishing a four channel particle counter.

The final pic shows the DC piping following the steel beam down the rest of the shop.  This connects to the table saw, the router table, an oscillating sander, the planer, and provides a connection for portable tools.



So anyway, how about those #'s I mentioned.

First, I tested the shop vac with the hose that connects it to the separator.  So just the shop vac in this test, no separator.  I got 27/24 (so 27-MPH at the center of the pipe, 24 at the edge).

Next, I connected that hose to the separator, and used a short (about 1') hose to connect to my test pipe.  I got 20/18.5 (again, 20-MPH at the center, 18.5 at the edge).  So the separator reduced my airflow approx. 24%.

Next, I connected the separator to my DC piping and closed all the blast gates but the one at my table saw, and took a reading there.  With the separator connected, I got 17.8/16.0 (I think below 20-MPH I start getting tenths of a MPH on the Kestrel, which is why I sometimes provide them).

Finally, I removed the separator by using a coupler between the shop vac and the DC piping, and took another reading at the table saw, and got 21/18.5.

It is interesting to note that, with the DC piping in place, the separator only reduced airflow by approx. 14%.  The faster the air spins, the greater the resistance.  So the losses from the DC piping actually work in my favor (sort of).