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Re: (ET) Ryobi 2400

Rebuilding a motor is not a big deal.....here's an old article that was 
sent a while ago......

Disassemble the starter\Alternator & remove the brushes.  Look at the 
commutator bars (segmented piece where brush rides with "mica insulation 
strips" separating each bar).  Check the stator & armature windings for 
broken windings and flaking\nicked varnish coatings. Polish commutator 
bars with emory cloth (don't use sand paper or steel wool!!)  Wash stator 
& commutator in hot soapy water.  Blow off as much water as possible.  
Obviously, compressed air works the best.  Using a cookie sheet or pie 
tin, place each of these in your oven (wife really appreciates this part) 
set to 220 degrees MAX!!!  This will bake the moisture out of the 
windings.  Leave in for 2 to 3 hours, remove and allow to cool to ambient 
temperature (this is important!!).  
Test with armature\commutator with Ohm meter from bar to bar.  Meter 
should read max resistance or very close to max indicating that there are 
no bar to bar shorts.  Check from each bar to armature shaft, again max 
resistance, indicating no bar to ground shorts.  Check the stator winding 
by testing the leads to stator frame for ground, again maximum ohms 
resistance should be present  If the resistance is very high, this is an 
indication that no "mechanical" shorts exist.  

As the brushes ride on the commutator bars, the commutator bars begin to 
wear along with the brushes.  Once the commutators bars wear to the point 
that the Mica insulation strips are even with the top of the bars, this 
causes intermittent contact between the brush and the commutator.  If this 
is a starter, this will cause a "flat" spot if the brushes land on the 
mica insulation strip and not on the commutator bar.  Sometimes you can 
tap the starter and it will turn.  On an A\C alternator or DC Generator 
this will cause the unit to reduce output or stop charging completely.  
This next step will describe how to undercut the mica insulation strips so 
that they are below the commutator bars.  Wrap the end winding with 
several rounds of tape to protect from damage to the insulation which is a 
varnish coating.  On a small commutator, use a utility knife and scrape 
the top of each of the mica insulation strips until they are about 1/32 to 
1/16 inch BELOW the commutator bars (with the knife blade parallel to the 
mica insulation, pull the knife toward you away from the winding and 
patience is the key).  Blow off any insulation and brass\bronze metal 
filings and recheck bar to bar & bar to armature shaft resistance (Should 
be Max resistance).  On a larger commutator, a hack saw blade works great 
to undercut the mica insulation.   If you have an industrial supply house 
in your locale, you can purchase winding insulating paint.  If not, I have 
used High Heat Engine paint as a substitute. Remove the masking tape from 
the commutator windings.  Next tape the commutator bars and brush holders 
with masking tape.  Apply a couple of coats of paint to the armature & 
stator windings.  This will cover any insulation (varnish is used on most 
windings as insulation) that may have been nicked or flaked off from heat. 
 Install new brushes & bushings as required and it should work like new. 

Erie PA

-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Joel Parks
Sent: Thursday, May 10, 2007 6:29 PM
To: Ron Blair; Elec-Trak email list
Subject: Re: (ET) Ryobi 2400

Hi Ron,

I'm copying this to the elec-trak list because I don't know who else would 

I imagine it would be cheaper to have a motor shop put new bearings and 
otherwise rebuild your motor than to buy a new one.  Unless Ryobi would 
you the part

Can anyone help with Ron's question?

My Ryobi BMM 2400 seems to have been appropriated by a friend.  Anyway I'd 
keep it.


----- Original Message ----- 
From: "Ron Blair" <rbi lisco com>
To: <et jpjt net>
Sent: Thursday, May 10, 2007 12:24 PM
Subject: Ryobi 2400

Hi Joel,

Found you on internet. I have a beloved BMM 2400 and I just lost the
motor. Do you know of any place to purchase parts? Would you sell
your 2400?



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