pdp1@EARTHLINK.NET on sun 29 feb 04
Hi Taylor,
If you may remove the Armature from the end-bells and center
section of the Motor Body proper, you may inspect and clean
it as needed.
Sometimes in these contexts the term 'clean' is a playful
euphemism for reduceing the height of the Mica as seperates
the Copper segments (or scrapeing out
carbon-oil-sludge-whatever as may fill up in there, in the
slots) of the Commutator, which one may do useing a section
of a Hack-saw-Blade or the like as is the right width and as
is groung to a noce 90 degrees on the end.
Or, is a euphemism for having the Commutator set in the ways
of a suitable Lathe and being trued up from it's
wear...thence to need to have the Mica seperators reduced in
their promenance as mentioned above...they need to be just a
tiny smidgeon below the height of the Copper Bars of the
Commutator.
So far as 'cleaning' in it's most literal sense...if the
Commutator may be acessed to some degree without
dismantleing the Motor proper...you may buy ( at say
'pepboys' or other automobile supply stores) an Aerosol Can
of 'Electrical Contact Cleaner' as is non flamable...and,
you may either spray it as the Motor is running, or, spray,
run, spray, run etc...
I sometimes use a little brush with say Acetone, or some
Alcohol, but as they are flamable, I get a little 'flash'
and so on...so you may be happier with a suitable
non-flamable Solvent as is made for the task...
If the Motor has a Manufacturer's nomenclature Tag, you
might call the Maker and see if the can give you a part
number or code for the Brushes, then either get them from
them, or call around and see who may have them.
If not, just call around or go on the internet and
see...useing measurements of the example you have, and
seeing about those as are intended for Motors of about the
same size as yours...
I have a maybe a thousand Carbon Brushes here as I have had
since I was 12...most of which are smaller sizes as for
'Drills' or small devices, but, if I have the right size you
need, I can set you up.
I would need one of your old ones to tell...
Good Luck...
Phil
Las Vegas
----- Original Message -----
From: "Hendrix, Taylor J."
Hey David (and all):
I'm asking you directly in addition to sending this query to
the list
because I have read several posts of yours about motor
maintenance for
pottery wheels.
(snip)
Taylor, in Waco
Steve Slatin on sun 29 feb 04
Taylor --
30 years without changing the brushes makes the brushes a likely
target. My slight experience with this is that commutators stay
clean from pressure from the brushes, but the gaps between the
commutators can collect various types of dust, oil, goo, etc.
Motor design will dictate whether you can clean without disassembling;
If you can reach in safely (with motor unplugged) rubbing alcohol on
a cotton swab will sometimes pull out enough of the collected dust
to make a motor run smoothly. I have also used a toothpick to scrape
the goo from the slot between the commutators with good results=20
(providing that the problem was goo).
With a 30 year old motor, it may be that there is some scoring on the
commutators. That usually calls for replacement.
There's one last low-tech problem that could be the cause of a=20
stutter (that I can think of). If the spring tension on the brushes
is sufficiently asymmetrical, at low velocity you may be having an
intermittent failure to make contact even with otherwise good brushes
and commutators. =20
Good luck -- let us know what works.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Hendrix, =
Taylor
J.
Sent: Sunday, February 29, 2004 7:56 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Brent motor maint.
Hey David (and all):
I'm asking you directly in addition to sending this query to the list
because I have read several posts of yours about motor maintenance for
pottery wheels.
A clay bud's Brent C stutters at very low speeds. It has done this ever
since I have been in clay (~2 years). She finally called Brent and the
guy said "brushes, or commutator is dirty." He mentioned possible
winding problems, but we both know that would mean throwing out the
motor and getting a new one.
I've done the brush thing in my skill saw more than once, so I
understand them and can change brushes no problem, but I've never been
sure how to clean off the commutator. What does one use on an electric
motor for cleaning? Will it be enough to clean the commutator through
the brush ports? Also, will Grangers (or others) have the brushes used
in the Brent motor? What motor specs do I need for getting the right
brushes? We are going to save clay bud some more money here, and I am
going to get to take apart (don't tell clay bud that I don't have to
take apart her wheel to fix the motor, hehe) a Brent C. She has had it
for 30 years and has never changed the brushes. Pretty good.
Taylor, in Waco
_________________________________________________________________________=
___
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Hendrix, Taylor J. on sun 29 feb 04
Hey David (and all):
I'm asking you directly in addition to sending this query to the list
because I have read several posts of yours about motor maintenance for
pottery wheels.
A clay bud's Brent C stutters at very low speeds. It has done this ever
since I have been in clay (~2 years). She finally called Brent and the
guy said "brushes, or commutator is dirty." He mentioned possible
winding problems, but we both know that would mean throwing out the
motor and getting a new one.
I've done the brush thing in my skill saw more than once, so I
understand them and can change brushes no problem, but I've never been
sure how to clean off the commutator. What does one use on an electric
motor for cleaning? Will it be enough to clean the commutator through
the brush ports? Also, will Grangers (or others) have the brushes used
in the Brent motor? What motor specs do I need for getting the right
brushes? We are going to save clay bud some more money here, and I am
going to get to take apart (don't tell clay bud that I don't have to
take apart her wheel to fix the motor, hehe) a Brent C. She has had it
for 30 years and has never changed the brushes. Pretty good.
Taylor, in Waco
John Jensen on mon 1 mar 04
Without any specific experience with the D.C. motors on the Brent, I
would refer you to Muirs" _How to Keep your Volkswagen Alive_,
specifically the pages on generator overhaul. You might be able to
clean the commutators with a bit of 400 grit wet/dry sandpaper folder
over a stick which would be pressed against the commutators as you spin
the motor.
Just a suggestion.
John Jensen, Mudbug Pottery
mudbug@toadhouse.com , http://www.toadhouse.com
pdp1@EARTHLINK.NET on mon 1 mar 04
Good mentions Steve...
If the spring-tension is too light, or if the Brushes have a
poor contact, or a poor fit in their holders, or if the
holders are dirty or otherwise resist the free float of the
Brushes, there can be arcing as is audable, as well as
likely to erode both the Brush(es) and the Commutator, and,
the arcing will tend to become worse as the speed is
increased...
Possibly, the problem mentioned, is one of the electronics
of the rheostat or controller, and not of the Commutator or
Brushes as
such...
Too...along Commutator interests, is that the gap of the
Brush Holder should be quite small.
Sometimes Brush Holders can migrate 'out' a little (being
usually held fast with a small slot-head or Allen head set
Screw at 90 degress somewhere to it) leaving the Brush
unsupported for too much distance. Motors as I have been
into seem to like a gap as is not much more than say a match
book cover is thick.
Best wishes,
Phil
Las Vegas
----- Original Message -----
From: "Steve Slatin"
Taylor --
30 years without changing the brushes makes the brushes a
likely
target. My slight experience with this is that commutators
stay
clean from pressure from the brushes, but the gaps between
the
commutators can collect various types of dust, oil, goo,
etc.
(snipped)
David Hendley on mon 1 mar 04
The description of the problem:
>A clay bud's Brent C stutters at very low speeds
This does not lead me to suspect a communicator/brushes
problem. I would think it is more likely an electronic controller
problem. But it could be either.
The ideal test, before you start fooling with the motor, would be if you
had another Brent wheel handy and could switch out the motors.
Then you would know for sure what needs to be fixed.
If it is the electronics, you would need to send the controller to
Brent for repair. If it is the motor, you can have a go at it.
The brushes for these motors are quite large. They can easily last
for more than 30 years. Of course, it is a simple matter to just
have a look at them. If there is more than about 3/8" (between the
spring and the end of the carbon), they should still be good.
I don't know what the specifications are; if I needed new ones
I would just take the old ones to the motor shop and ask for more
of the same.
I have not seen a dirty communicator on a DC potters wheel motor,
but I have seen motors that stopped working because they were
so gunked up (my Bosch jig saw, for instance).
If it is so dirty in there that it is affecting the turning of the armature,
I think you need to take the motor apart to adequately clean the
contacts. If you just spray stuff in the brushes holes you are only
moving the dirt around, not getting rid of it.
It is not a big deal to take the end of the housing off the motor, to
get to the communicator, to clean it.
The best cleaner is "electrical contact cleaner", which is made for
the job. It comes in an aerosol can. Spray liberally and wipe with
a clean cloth. Alcohol also works as a solvent/cleaner.
David Hendley
david@farmpots.com
http://www.farmpots.com
| |
|
