Tuesday, November 4, 2014

Down a Dusty Road

A bit over two years ago I acquired a 7.5hp dust collection system from a High School in the midwest. They needed a bigger weight training room apparently so the wood shop program had to go. I wrote about the initial set-up of that system in a post entitled Shop Vac Review.

The system, originally manufactured by Air Sentry, has been working decently, but I came to see that it had a number of shortcomings. One of those was the box upon which the cyclone was mounted, a box containing a pull out bin on wheels for the chips:


It worked okay, though removing the bin always entailed dealing with a bunch of shavings that had made their way down the sides of the box and not into the hopper. So, it was a case of pulling the bin out and then doing a bunch more shoveling.

A bigger issue though was that of the way the bin was enclosed in the box/stand- you couldn't readily ascertain where things were at fill-wise. To check the level, one had to undo four locking latches on the front and remove a hatch door, then wrestle out the bin and have a look. It wasn't especially convenient or pleasant to do that task, so I would tend to make a guess more often than not as to where things were at rather than investigate the actual situation. Most of the time that worked well enough, however....

One time I let things go too long and when I pulled out the bin I discovered that the entire cyclone was utterly full. I was swimming in chips. I emptied it out and did a bunch of shoveling with the cascading pile of shavings which poured down seemingly endlessly. I reached up into the cyclone with my arm until I couldn't feel any more shavings. Once done, I put the bin back in, latched the hatch, and got back to the task at hand.

Trouble was, there were chips still packed in at the top of the cyclone. They had packed in there pretty good and had not fallen to the bottom. I guess I assumed with the funnel shape and all that chips would always find their way down. Not always.

So, I got back to planing, assuming the system was clear, when in fact it wasn't. The chips could not go down the jammed-up cyclone, so they headed to the next available depot - the bag house:


The bag house contains 40 cylindrical cloth sleeves of about 5" diameter which serve as the air filter, and there are two small pullout drawers at the bottom where the dust is meant to end up. The way the system is supposed to work is that the cyclone separates the dust from the chips, with the heavier chips dropping down to the bin below and the dust carried into the bag house and deposited in the aforementioned pair of drawers.

I kept planing that day, and after a while, well before I would have expected the bin to have gotten full, chips started coming out the planer. Uh-oh. Something new and exciting awaited....

It turned out that I had completely filled the bag house with chips, up every single one of those cloth filter sleeves. Two days of dirty dusty work ensued, massaging chips out of sleeves, etc., to get the whole works clean again, an experience I would prefer to avoid repeating.

When the system was working as it should I found that the bag house dust drawers accumulated next to no dust. this is hardly surprising since I lack sanding equipment and do not generate dust very much. 99% of what I make in particulate waste is chips. So the rather large bulky bag house was probably better suited to a situation in which a lot more dust was being produced. It took up a lot of room and didn't really earn its keep, so to speak.

Further, I was never sure just how well the cloth filter tubes were working in terms of permitting good air flow for the system. I considered washing the tubes to clean them, but was concerned that water might cause them to shrink and then be difficult to refit into the metal plenum, so I didn't explore that avenue. They certainly seemed dust caked, but the system did its job reasonably well so I just kept going, but a plan for improving the system was in full swing.

I just got around to revamping my dust collection system in the last couple of days. I pulled the motor off of the top of the cyclone using a pulley affixed to the ceiling and a 1-ton come-along. That motor is quite heavy and by holding it suspended in place I could avoid having to disconnect the wiring.

Then, with the help of my shop neighbor Joe, separated the cyclone from the dust collection box/stand and dragged it off to a nearby metal fabrication shop. There they cut the bottom few inches off the cyclone, cut off the old mounting flange and welded on a new flange at the bottom.

I picked up the cyclone canister and dragged it back to the shop this morning:


I sprayed some primer on and took lunch so as to remove any temptation to handle the piece with the primer not dry.

After I returned I was faced with the task of getting the cyclone back into a vertical position by myself. The canister weighs more than I do I'm sure, and is quite awkward to handle due to its shape.  So, I improvised, rigging another pulley and rope system from the floor to the ceiling:


I couldn't readily use the come-along, to the left side in the above photo, as it was supporting the weight of the motor and impeller. It was unfortunately a little bit in the way too, but I managed to work around it.

My first step was to get the canister up onto a pair of sawhorses:


To the left of the above picture you can see the black metal stand which I had fabricated at the same local shop to carry the cyclone assembly.

A while later I had the canister up on to that metal stand:


And a while after that I had it in a vertical orientation and bolted onto the stand, and had started re-connecting the 10" and 12" duct work:


After the canister was in place my shop neighbor appeared and was able to give me a hand remounting the motor and impeller to the top of the canister, and then placing the replacement for the bag house, a pair of mesh-wrapped pleated filter cartridges attached to a plenum, all from Oneida Air Systems:


The black plastic buckets on the bottom of the filters are where the fine dust will end up. I don't expect to have to empty these very often, and I don't think the filters will tend to get plugged too quickly. The two filters take up 1/4 of the space of the old bag house.

Under the stand I have now positioned a pair of 55 gallon drums for the chips, also from Oneida, which will connect to the cyclone canister end with a flex hose and a pants wye duct fitting:


The pants wye got left behind at the metal fabricators by mistake so I'll have to wait until tomorrow to finish connecting it up.

Another view of the revamped system:


The new stand has raised the cyclone up nearly 24", which has also had the benefit of removing two elbows from the large duct portions, and that should further improve airflow in the entire system. With the bag house gone, I have gained additional light from a large window previously obscured. Seems like a win-win, but it was a day of slogging and heavy lifting to get there.

I look forward to seeing how it works tomorrow.

All for now - thanks for dropping by.

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