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Author Topic: PM Research generator issue - new build  (Read 530 times)

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PM Research generator issue - new build
« on: July 24, 2021, 09:12:46 am »

  I finished my PM generator last night, and hooked it up
as a motor to test  - the easiest test to make.  It runs,
but with a light vibration, like the armature shaft is
precessing in the bushing rather than spinning.  Not
smooth, silky, or sewing-machine like.   Properly oiled,
it even makes a squeal from time to time.  I checked
for slop at the shaft end,  and there was enough to give pause.
I would try 'running' the problem away, but that only works if
it is tight.  What do you do if it is, out of the box, loose?
It should be smooth.   Any ideas or similar stories?  I'm
a bit disappointed. 

Wayne
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Re: PM Research generator issue - new build
« Reply #1 on: July 24, 2021, 03:00:43 pm »
Was this an un-machined kit, or one you assembled only? I machined one of these a number of years ago, and swore i would buy the next one fully assembled! As i recall, the bolts holding the 2 ends on had to have the bolts torqued all the same- it was THAT critical. It would not run properly till i did some tweaking with those bolts. I do recall the parts being very tiny!
crazydoug
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Re: PM Research generator issue - new build
« Reply #2 on: July 24, 2021, 05:48:10 pm »
It was a machined kit.  I'll try adjusting anything that can be adjusted.
There is no denying the play in the bearing.  I'll run it at a low speed
and readjust the screws holding the end-caps on.

Well, no joy.  Everything is correct.  I'll have to reach out to PM on Monday.

Wayne

 
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Re: PM Research generator issue - new build
« Reply #3 on: July 25, 2021, 10:44:02 am »
I fussed with the endcaps, shifting and tightening them down
in different ways.  I even ran it while tightening to see if
that slows it down but that is not the problem.

So, I let it run at the fastest 'smooth' speed for several hours
(well lubed) and this is the result.  The chattering rolling-in-
the-bushing sound always starts at the same speed (slower is
acceptably smooth) then smooths some when I increase it.  Therefore,
I'm guessing this is a harmonic problem that is only bad at
certain speeds.  Of course, if there was no bushing play it would
not happen at all.  To that end, I'm going to inquire about
the price to buy another set of machined end castings.  There may be
a way to use ball bearings as there is extra metal in the bearing
area.

Wayne
 
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