Miser
Member
Registered: 12/02/06
Posts: 291
Loc: Gurnee, IL
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I'd like to get the RI motor from a Uni inspected...it runs well but I know it's had limited use in the last 20 years and questionable storage (though it's very clean.) I've got a couple of questions and looking for advice.
1. What should I expect to pay to have it inspected? There are a few motor shops in my area. They appear to service the usual brands and are capable doing thermal inspections, rewinds, rotor/shaft tuning etc, etc.
2. Does anyone have any recommendations for a rebuilder in Chicago or Milwaukee they've used and trust? (I'm halfway between the two.)
Any other considerations wrt the RI motor?
thanks!
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Jonny Rocket
Member
Registered: 09/01/06
Posts: 718
Loc: Indianapolis, IN
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If its an old unisaw, and with a RI motor I assume it is, ask on owwm.org. There are some guys there from the area and they might be able to give you a good answer. Mostly, they just need bearings and maybe brushes.
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Unisaw A100
Member
Registered: 03/05/04
Posts: 4113
Loc: South End of The Tamarack Swam...
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Quality Electric on 35th. and Hopkins in Milwaukee. I walked in with mine and the counter man ID'd it from across the room. I've heard stories where some motor repair shops don't know what a replulsion/induction motor is.
I feel sorry for people like that.
Unisaw A-100
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TDKPE
Member
Registered: 10/15/02
Posts: 5318
Loc: Rochester, NY, USA
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Unisaw A100 said:
Quality Electric on 35th. and Hopkins in Milwaukee. I walked in with mine and the counter man ID'd it from across the room. I've heard stories where some motor repair shops don't know what a replulsion/induction motor is.
I feel sorry for people like that.
Unisaw A-100
I started to post that he should find an old motor shop with an old guy working there who actually knows what an R-I motor is, but decided not to for some reason. 
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Tom
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Ingjr
Member
Registered: 06/29/07
Posts: 1089
Loc: Spring Hill, FL.
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I'll bite just cause I don't know. What's the difference between a RI and a plain old I motor? Can't hurt to know in case I run up against the question. 
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The older I get the faster I was.
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TDKPE
Member
Registered: 10/15/02
Posts: 5318
Loc: Rochester, NY, USA
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For starters, they're mostly old. Crispy insulation, weak bakelite, etc.
But more importantly, they have systems and parts inside that aren't found in three-phase and split-phase (which includes capacitor-start) motors, like armatures, brushes, wire-wound rotors (though some specialty 3-phase motors also have wound rotors), usually some sort of shorting ring on the armature (shorts all the rotor's windings together when up to speed), and even a brush lifter mechanism (on most, but not all). Many of those parts are hard to find, and impossible to find new.
If you walk into a motor shop with an old R-I motor, and the kid behind the counter with the peach fuzz on his chin gets big eyes and says "Wow - what's that?"  , do a U-turn and try the next one.
Here's an old 1 hp Century R-I motor I haven't decided what to do with yet. It's a monster compared to the typical modern motor. The little black one in the background is a single-phase induction brush motor from the early part of the last century, with the primary windings on the rotor instead of the stator. It uses slip rings instead of the typical commutator bars. Someone posted a similar one here, made by GE, a while back.
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Tom
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Miser
Member
Registered: 12/02/06
Posts: 291
Loc: Gurnee, IL
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Thanks all...appreciate it.
I THOUGHT about tackling this myself but I've never opened up an RI motor before...I've got a buyer for my old saw and told her I'd deliver it Thanksgiving weekend.
I'm anxious to get this saw setup and put to work versus spending a month or two on a major reconditioning (the patina and stain splashes from a dropped can look old-timey and I like it.) I'm going to rewire it with a safety switch, clean the top and cut wood.
Since the motor sings today, I'm assuming (maybe a mistake) it needs minimal/typical re-work. What are the minimum must-do's? (bearings? bearings and brushes? other?)
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*Chris*
Un-Zipped
Registered: 12/31/04
Posts: 9380
Loc: Westford, MA
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You have two options, take it apart and post some pictures here, with a running motor a lot can be diagnosed through a visual inspection of the brushes and commutator. We can give step by step instructions if you want. The only think you can't check visually is the condition of the insulation on the windings, for that you need a tool called a "megger."
Second, as others said, keep calling around motor shops and small tool repair shops until the guy on the other line says yes, "I know what a Repulsion/Induction motor is", or even better "man, don't those old Unisaws run sweet."
I had to go through a dozen motor shops in the greater Boston area before I found one. I have sent dozens of people to this guy with great results.
The diagnostic fee seems to be $50-100 and is usually applicable to any repairs that are necessary.
Chris
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"GGaippe, Lemmeesee, You joined 04/24/00 and have 50 posts, Joe joined 07/11/03 and has 5058, quite a bit of which has been useful information. Sounds like you are a lurker without too much USEFUL to say, so GO AWAY. " T-Man
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Pirate
Member
Registered: 08/12/06
Posts: 1325
Loc: SW FL
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I would do what I did when I got my 1946 Unisaur. Take the inspection plates off the bell end and check to see how the brushes are. They are only for starting and last a long time. Be sure the brush springs are intact. Feel how the bearings feel when you turn the motor, without the belts on.
If all seems OK, put the covers back on and use the saw.
Mine has been fine for 4 years or so that i've had it.
Save the money you would spend on an inspection, and spend it on repair in the future if needed.
I would hate to have someone start poking around inside and break some insulation on a winding or something and having it turn into a nightmare.
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I long for the days when Coke was a soft drink, and Black and Decker was a quality tool.
Happiness is a snipe free planer
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TDKPE
Member
Registered: 10/15/02
Posts: 5318
Loc: Rochester, NY, USA
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*Chris* said:
. . . the guy on the other line says yes, "I know what a Repulsion/Induction motor is", or even better "man, don't those old Unisaws run sweet."
Or if the guy on the other end uses the word "bullet", without you saying if first, it's a good sign.
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Tom
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