Cyclone impeller misalignment

[Dale Critchlow]

I am building the Bill Pentz "Budget Blower" using the 14" impeller from Sheldon Engineering. I torqued the three screws sequentially until I reached 6foot-pound which is recommended.

When I started the motor I could see that the impeller was wobbling. It is out of parallel with the motor plate by almost 1/8". I took it off and carefully torqued the screws again with the same result.

Does anyone know if this is normal? Does it cause a problem?

I will contact Sheldon on Monday, but thought someone here might have the answer.

Thanks,

Dale Critchlow

[Jim O'Dell]

While I can't comment as an authority, I would think that this is NOT normal. That heavy of an impeller spinning at that speed would do some serious damage. Have you tried to spin the motor without the impeller on it to look for a bent shaft? Could possibly happen in shipping, especially as heavy as that motor is. Maybe Bill P. will see your post and make a comment. Jim.

[Dale Critchlow]

Jim: Thanks for the reply. I checked the motor shaft for wobble and it is ok.

The impeller doesn't wobble in the radial direction. Rather, the problem is that impeller is not parallel to the face of the motor so you see a wobble as you look at it from the side.

Dale

[Ken Garlock]

Dale, as I recall, my impeller had what I would call a sizable balancing weight welded to the backside of it. I attached the impeller to the motor, clamped the whole thing to the bench without the blower cage, and wired it up. At the other end of the shop, at the breaker panel, I put the power to it. It ran just fine. After a couple test runs, I got brave enough to sneak up on it while it was running, and feel the motor for vibration. There was just a little, but IMO it was not enough to be concerned about.

You may want to measure the run-out(wobble) near the edge of the impeller, and sent a note to Mr. Paton(sp?)

[Jim O'Dell]

Jim: Thanks for the reply. I checked the motor shaft for wobble and it is ok.

The impeller doesn't wobble in the radial direction. Rather, the problem is that impeller is not parallel to the face of the motor so you see a wobble as you look at it from the side.

Dale

I'd ask Sheldon what the chances are that the mounting hole is a little off center, if I understand you correctly, although I would think that this is a slim possibility. I'm envisioning a ceiling fan wobble where one blade is closer to the ceiling than the others. Have you tried moving the mounting collar around where the bolts line up to the different mounting holes? I'd number them with a pencil and try all the combinations. (my Pentz/Morgano impeller has 3 bolts, so only 3 possible combinations) At least it's something to try in the mornig after a good nights sleep :rolleyes:
Oh, and is your motor face parallel to the mounting board that the impeller sits next to? If it is off, it may give the impeller the illusion that it is wobbling. Jim.

[Ken Fitzgerald]

Dale, if I read your post correctly it sounds like the hole in the impeller is not perpendicular to the face or surface of the impeller. If there is no runout on the motor shaft try using a single point on the motor housing for a reference and measure from that point to the face of the impeller ...then rotate the impeller 90 degrees and measure again.....repeat this at 4 points 90 degrees apart on the impellar...do you get the same measurement?

[Dale Critchlow]

Ken, Jim: Thanks for the responses.

Ken: Your interpretation of the wobble is correct. The measurements you suggest are the ones I made. I measured the distance from the edge of the impeller to a point on the motor plate. Then I rotated the impeller and measured again to the same point on the motor plate. This is the way I determined that the wobble was almost 1/8".

Jim: Your analogy to the ceiling fan with one blade closer to the ceiling is correct. The suggestion of remounting the impeller with a 120 degree rotation is a good one. I will try that. I shouldn't see a difference unless the motor shaft is bent or the press fit mounting is defective. Neither of these seem likely, but it is worth checking.

As far as I can tell the impeller is balanced ok radially. I haven't done Jim's hands on test yet but I will.

Dale

[Frank Guerin]

I don't even own a cyclone so I'm just guessing here. If your impellor has a tapered hub that your impellor bolts on to you may have it slightly off set.

[Jim O'Dell]

Dale, since it is the same side of the impeller that is closer to the motor all the way around, then it won't be the mount being off parrallel with the motor face. It would have to be the impeller's hole for the motor shaft slightly out of perpendicular since you find no run out on the motor shaft. I'd mark the low spot on the impeller and the motor face, then change the mounting holes. If the low spot stays in the same place on the impeller, it has to be the impeller. If it changes then there may be something wrong with the taper hub and or the impeller. Definately get Sheldon to make the determination. Jim

[Dale Critchlow]

I contacted Sheldon Engineering concerning the wobble on Monday by email. The response was as follows:

Dale,
Those wheels are hand-made and are not made perfectly true. We do balance all of them, though. If you can tell that the wheel is out of balance (i.e. shakes, wobbles, etc.) than, let me know and we'll send you another one. If it's just not true, but does not make vibrations, leave it and run it. That is normal.
Please let me know.
Regards,
Vladislav Petkovic

I then called Vlad and told him that I could feel vibration which I put my hand on the motor. He offered to send me a new wheel which I received on Thursday. It has a wobble of only 1/32" and had very little vibration.

I am impressed with the response from Sheldon. Bill Pentz talked them into bulding this wheel for woodworkers. They are standing behind their work.

Dale