Blower Head's Up - Caution

[Bill Pentz]

I'm sharing a serious caution from a fellow engineer who is building a cyclone using my Cyclone Plan (http://cnets.net/~eclectic/woodworking/cyclone/CyclonePlan.html) and Budget Blower (http://cnets.net/~eclectic/woodworking/cyclone/BudBlower.html) plans. In looking at historical posts on this forum made from my design directly or from the Dust Eliminator cyclone kits from my design, he sees quite a few that appear to be turning their impellers backward.

Running an impeller backward in my "budget blower" plan will actually make for a little more airflow and better static pressure, but sets up nasty vibrations. These vibrations can ruin a motor and make the light weight aluminum impellers fail, meaning fly apart. All impellers should be regularly inspected and cleaned when needed to ensure they do not get out of balance. Having had one of my test impellers fly apart during testing, I can assure you that this is not something to mess with!

Coupled to this caution is a further concern about the use of the large aluminum Cincinnati Fan backward curved impellers. This particular impeller was designed for clean air, and needs to be further protected from material hits. When a cyclone plugs or the bin gets full, the impeller takes material hits (about once or twice a month for most of us). Finally, any time you remove one of these Cincinnati impellers, you must replace the special star type Allen screws and dress the motor shaft or your impeller can slip off during operation (learned that one the hard way myself). I much prefer the far stronger compression arbors.

I personally started two years ago with one of the Cincinnati Fan aluminum impellers and still have it, but upgraded my own system to use a heavy steel impeller. I recommend the less costly Jet impeller or safer Sheldon's Engineering steel impellers that use compression arbors.

My plans are correct. They carefully specify the direction of rotation for the blower and recommend use of good heavy steel impellers. Please note the proper orientation of the blower outlet compared to the way the curved parts of the blades face.

bill

http://cnets.net/~eclectic/woodworking/cyclone/construction/ImpellerRotation.GIF

[John Miliunas]

Once again, you've proved your dedication to the field you've given so much to! Yeah, it sure would be tragic if someone trying to spare their health by eliminating dust would somehow be hurt by flying metallic debris! Thanks for the warning, Bill! Oh, and hope your own health is holding up ok! :cool:

[Dr. Zack Jennings]

Thanks for the information Bill. It's good to see you on the Forum.
Please keep us informed.

[Terry Hatfield]

These are good suggestions for ANY cyclone. You should never operate any cyclone with the chip bin overflowing or when the cyclone itself is plugged. Cyclone impellers are designed to be on the "clean" side of the cyclone. Regular bag type DC impellers are designed to be on the "dirty" side of the blower where they must take a massive amount of material hits every time the DC is being used.

While no blower is truly totally "clean", the cyclone itself is seperating most of the dust and leaving it in the collection bin. Only a small amount of remaining dust is passed through the blower and into the filter as long as the collection bin is not overflowing. If this is the case, the chips will bypass the bin, go through the blower and end up in the filter. This is also possible if you have a leak in the cyclone or collection bin. A past customer recently emailed me that he was getting a bunch of debris in his filter. I told him to check for leaks and sure enough, he found a small leak in the hose connecting the drum to the cyclone. It only takes a tiny leak to make this happen, so be sure your system is totally sealed.

You should monitor the level of chips in the bin before each day of shop time, and during the day when there are a bunch of chips being collected to make sure that the bin is not too full. You will know very quickly if you run any cyclone when the bin is overfull because the filter will be almost immediately plugged and it will be a major ordeal to get it cleaned out completely. It is a bunch easier to deal with the chips BEFORE the bin is overfull and the filter is plugged.

I have never personally been able to plug the DE cyclone. I conducted a test recently so I could respond to an email question. I conducted the test using a yellow pine 2 X 12. I ran a 4 ft. piece of the 2 X 12 through my planer removing 1/8" at a time until it was 1/4" thick without being able to create a plug in the cyclone, but this should be monitored just in case.

If you need to inspect the impeller, it can be removed from the blower housing without removing it from the motor shaft by seperating the blower halves. There is no need to remove the impeller from the shaft. If you do remove it, Bill is totally correct, you MUST replace the allen screws and check the motor shaft being sure to remove any burrs left from the original installation. This is clearly covered in the instructions that come with every CF impeller.

I personally tested the CF 14" aluminum and the Jet 14" steel impellers turning in reverse and in the correct rotation. They do move more air and make more sp turning in reverse than when they are turning in the correct direction. They both are super loud running in reverse and the CF actually pulled more amps running backwards that the Leeson motor is rated for. Both also make plenty of cfm and sp turning in the correct direction and sure are easier on the ears. I totally agree that everyone should be running the impellers the direction they were designed to run.

Terry

[Bill Pentz]

Thanks for the ongoing support!

My health is still less than steller. Getting through congestive heart failure and double pneumonia is not all that easy or quick. I'm up, doing a little work, but run out of energy quickly.

Getting back to the messages:


1. In spite of having owned and used one on my own cyclone for over two years, the Cincinnati Fan backward curved impeller is not one I recommend highly for my budget blower to power a cyclone. I'm not pleased with its high cost, poor inconsistent dealer support, poor arbor mounting, and it being light aluminum that will not take material hits.

2. Although my site is and has always been correct in terms of how to build the blower and turn that impeller correctly, many built their blowers and turn their impellers backward. I posted wanting each to carefully check their impellers because I would be most disappointed if someone got hurt.

bill

PS: Here is a peek at how I monitor the condition of my own impeller. Half of the blower sidewall is made with polycarbonate (near bullet proof) clear plastic letting me just see inside. When I need to clean, I simply take off the blower outlet and spray down with compressed air. If there is a build up of resins, then have to take the blower housing off and clean with solvent.