Buffer Spinning Backwards

Tuesday I was sanding blades with greasless on the buffers for about 4 or 5 hours. Doesn't seem long but Arizona summer heat is hard on you and equipment. When turning the buffer off, it would slowly labor at restart.

Filthy and tired, showered up, went out to get something to eat, and walked into the start of our big dust storm. Wound up as dirty as when I was working. If you didn't see the videos, a clip is below.

To the point. Today, got back into it on compounds. Buffer started slowly, touched black compound to wheel, and the buffer wanted to kick it out of my hand. It was spinning backwards. May have been Doomsday for a blade if I had jumped right in.

Stopped it, hand spun it the right way. When I started while it was coasting, all fine and normal now at start/stop.

I blame it on the Doomsday storm

http://www.youtube.com/watch?v=8W4Cx44XKZ4

That is interesting! The last cheep grinder I used for buffing had the same malady! I LOVED it! I could spin it backward and hit the switch. Made cleaning the pad easy!

My folks live in Sun City, just outside Phoenix. They are OLD, and mom has breathing problems. They never called or anything. First I heard of it.

Is everything ok in Phoenix now??

Wow, amazing footage..

M

Quote:

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Originally Posted by mjhammer

My folks live in Sun City, just outside Phoenix. They are OLD, and mom has breathing problems. They never called or anything. First I heard of it.

Is everything ok in Phoenix now??

Wow, amazing footage..

M

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The storm happened about 8:30m

My inlaws used to live just west of your parents, in Sun City West. After 7pm, that whole area is very quite. If your parents are anything like my inlaws, they were probably in bed by the time the storm hit.

If they got any damage it would have been from whatever the wind could tear up. They'll need to hose the patio off, and get the window washers to clean the glass. Maybe check the ac and swamp cooler to make sure they didn't get struck by debris.

It only lasted an hour or so. Very hard winds, and very dirty. Was odd when bursts of showers came down. Seemed like raining mud.

Sounds like a hairy ordeal! Glad all are alright! Back to the buffer. I am no electrician, but there is something in the phasing of an AC motor like that to make it rotate a certain way. I know some can be rewired to spin opposite. The lo/high voltage/spikes probably caused an internal short. In my case it made a motor which would run either direction. All I had to do is spin the wheel in the desired direction and hit the switch! Lasted for many, many years like that!

Most of my experience in motors for 30 years of being an electrician are for 3 phase jobs... if it spins backwards, swap any two of the 3 supply leads.

Single phase AC motors have a capacitor circuit that dampens the appropriate cycle at startup causing the motor to spin in the desired direction. Failure of this component is the likely culprit.

http://www.howeverythingworks.org/su...ric_motors.pdf

I don't suppose it's actually necessary to replace this capacitor, as long as the guy using it knows how to get it going in the right direction.... but there you are.

:D

That's where I was headed as well. If the heat cooked the cap, or enough dust got in there to stop the start switch from working (some have one and some don't) then it might cause something like this. Just don't let the motor labour when it starts of you'll burn it out.

10-4.

"Locked rotor' currents in aging motors are the main causes of catastrophic failures.

In my town there are still several businesses that rebuild electric motors of all types. From 12 volts up to 400+ trip phase... for well under the cost of new gear.

An overhaul with new brushes, stators, starting circuits, ect... before the ending explosive result... could be very cost effective in the long run.