Got a CV500 Dillon tumbler which I've had for 15 years or so, and bought used. About 2 years into ownership the motor quit. When I called Dillon so see if it was covered under warranty it wasn't, but they suggested they could re-motor it for a small fee and I sent it back.
They installed the CV750 motor, which was an upgrade. But lately I noticed it was going "wonky" again, so I wanted to share my experience, what I did for a fix, and why these units experience issues.
MY ISSUE
Last weekend when running my tumbler I noticed it would run fast, then slow down to a crawl, then speed back up. Like it was on some kind of motor controller. I thought it strange becasue there's no circuit board under there, just a simple fractional HP electric motor.
When I grabbed the fan/flywheel I noticed it had a definite free play in the motor bearings. Not a clunk-clunk like bad bearings, but a distinctive back and forth of about 3/16" at the fan. I Googled the issue and it seems like everyone has had this issue without any resolution.
My particular issue was that these motors were designed for use on small fans. As such there was no unbalanced load, and quiet running was a priority. So they had mounted both ball bearings in rubber cups. However a vibratory cleaner has an offset weight that makes the unit shake violently. The addition of this offset weight had simply worn out the rubber cup on the flywheel end. In fact, it was in shreds! This is why the shaft was able to move back and forth.
An aluminum cup was made up to take the place of the rubber bush on the flywheel end only. OD of 0.850", ID of 0.750", and length of 0.25". (Epoxy could also be used to fill this void, but I concluded that a metal ring was better for me.) The bearings were still good, it was the slop in the rubber cup that allowed the armature to rub the body, which then caused the slowing. There was much evidence of rubbing on both parts, but no real damage.
I'm glad to report that it's back together and running at full speed today. Without the full rubber dampening, the motor IS slightly louder, maybe 3 or 4 dB, but since I usually tumble outdoors this is a non-issue.
REPLACEMENT
Part of the problem for Dillon is that these small motors keep going out of production. AO Smith, who made my motor, was sold to Century Motor, who promptly stopped making that motor. The closest replacement I could find is: Dayton 4M080, which has a 2" long, 1/4" shaft fitted with ball bearings. This is a 120VAC, 3000 RPM, 1/40 HP shaded pole motor, and is available from Grainger or on Ebay for about $50. You will, however, need to remove the motor screws and insert them from the opposite side to use it.
DIS-ASSEMBLY
Getting the motor out is quick and easy, but you can break the special motor screws (don't ask me how I know this) if you aren't careful. Turn the unit over and remove the 3 Torx head screws. Lift off the gray bottom. Turn the 3 spring units CCW and unscrew them completely. (You may find it necessary to hold the 3 screws inside the bowl.) Lift off the black metal motor mounting plate. On the underside of the motor plate you'll see 4 nuts that retain the motor. Remove the 4 nuts to remove the motor. The fan/flywheel is held on by a single hex socket set screw; just look for the hole. Use a marker to denote which gray bearing housing goes on which side of the motor body before disassembly. When the 4 black screws are removed the motor will fall apart.
Hope this helps.
