Replies

1. 
   scooter1 | Jan 15, 2003 04:35am | #1

   Shorted Armature? Pull the Motor and have it bench tested by someone competent?

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927

1. 
   wcperry4 | Jan 16, 2003 03:30am | #19

   Thanks for the response.  Yea, that's what everyone seems to think.  I'm hoping I can get it fixed cause this saw's not that old.  Thanks again.

2. 
   nigelUsa | Jan 15, 2003 05:50am | #2

   The old brushes got so low you ended up spark erodeing the comutater (where the brushes ride) its now rough and beat. Pull the motor and take to a repair shop (business yellow pages) might be able to fix it, get a price first.

1. 
   wcperry4 | Jan 16, 2003 03:31am | #20

   Thanks for the response.

3. 
   bill_1010 | Jan 15, 2003 07:46am | #3

   once you get the motor fixed, realize that you might be overworking your saw.

   Dadoes are tough on CS, take light passes.   For ripping try a SHARP thin kerf saw.  overtaxing the motor is rough on saws and will burn them up like you describe, or add to the negative effect and lower the end life span of your motor.

1. 
   cheakamus | Jan 15, 2003 09:17am | #4

   Now you've got me worried!

   I've got a 1950 Unisaw with the original 1 HP motor (about twice the size of the new 3 HP motors nowadays). I can rip 8/4 oak in small quantities (say, 4 legs for a case piece) with no problem. But I've never even thought of checking the brushes. I don't know if they've ever been replaced or even if they're accessible without taking the motor out and disassembling it. Should I be checking them? Is there anything else I should be doing vis-à-vis keeping the motor healthy? (I don't think I can afford to replace it, unless my wife says I can sell one of the kids <G>!)

1. 
   riverr1 | Jan 15, 2003 10:07am | #5

   More then likely your motor does not use brushes.

2. 
   TKanzler | Jan 15, 2003 04:26pm | #6

   That's a Repulsion-Start, Induction-Run (RI) motor, which does have brushes, and they run smooooth.  I believe you can inspect the brushes through elliptical access panels on the dumb end.  But if you have the cast iron "goose egg" motor cover, access is a pain.  It's been 25 years since I've used a Unisaw with that motor, so I don't recall much more than that.  But if you need to service that motor, make sure you take it to a motor shop that's worked on those Unisaw motors.  The folks at http://www.oldwwmachines.com may be able to guide you there.Be seeing you...

1. 
   DJK | Jan 15, 2003 05:22pm | #7

   That RI motor is a keeper and can be repaired. I've repaired four in the last three years. If you have replaced the factory brushes, great. The commutator should be cleaned and "graded" with a commutator stone. Start with a fine stone and check your progress. The best method is to remove that end bell of the motor and clean it up; blow out the dust, check the copper weights and retainer spring also the brush pressure springs. If you have access to a lathe, mount the armeture and clean up the commutator while spining it. If the motor ran fine before this problem, DON'T change the brush timing during disassembly. Often the weight retainer spring becomes "work hardend" and should be replaced. Ried Tool has them for about $1. While it's apart, change the shaft bearings. I contacted Marathon Electric about info on the RI motors, they did not have anyone employed who knew anything about them. The microfich for that motor is #4 and so faded they could not read it or make a copy. I will gladly give you $100 for the motor or contact me and we can discuss the repair on the phone.

1. 
   TKanzler | Jan 15, 2003 06:11pm | #8

   I think you meant to direct your reply to CHEAKAMUS, but I certainly agree that it's a keeper.  The Unisaws I used long ago that used those motors and some very well worn belts running loose, were the smoothest cabinet saws I've ever used, bar none.  Those saws also run at about 3200 rpm arbor speed (rather than the current 4000), and between the extra blade torque due to the lower speed, and the motor's torque characteristics, they never seem to feel underpowered, even though they're only 1 hp.  I seem to recall that there was also a 1.5 hp bullet motor, but it was 3-phase only.  The fellow at angelfire in Vermont (don't remember the company name at the moment) had a few he was selling at $25 per, but they may be 3-phase. 

   By the way, I've seen posts where people have said that the aluminum motor sheaves are no longer available (5.5" diameter, or thereabouts), but last time I checked with Delta (just out of curiosity), they said they stock plenty.  Be seeing you...

2. 
   DJK | Jan 15, 2003 07:23pm | #9

   Sorry for the confusion. Wish some of the youngsters on this sitecould use a vintage Unisaw and see what they are missing. Grizzley, Grizzley, Grizzley, if they only knew, but if they don't it's more vintage equipment for us. I have four of the 1725 rpm motors all three phase. They run sooo smooooth. The slower arbor speed requires a slower feed rate, ok for solid lumber but blades for sheet goods like a faster arbor speed. On a couple of my vintage Unisaws I've installed Baldor three phase 3450rpm motors from the '70s. They fit the oval hole saws ( even with the cast iron cover installed ) and run as smooth. The 5.5" pully is about $96 from Delta but the same if purchased in Canada. Factor in the exchange and save 40%. The newer pully is redesigned with a flat hub , the way it should have been, not the dished hub. I always check the price in Canada before ordering.

   Dave Koury

3. 
   TKanzler | Jan 15, 2003 07:55pm | #10

   Well, since you brought it up, where are you getting parts in Canada, if you don't mind my asking?  The reason I ask is that I need a new motor for my Delta 12" RAS, and it's $600+ from Delta and their authorized distributors in the US.  Since I can't find a used one anywhere, and the newest style will fit (it's a +10, but it was upgraded once already with the rectangular-ish aluminum motor and new style yoke and guard), my only course of action is to buy new.  40% savings is a lot of money on $600.  Be seeing you...

4. 
   cheakamus | Jan 15, 2003 09:10pm | #13

   Yes, my 1950 saw runs incredibly smoothly, and I'd always wondered why it was powerful enough to cut whatever I ran through it, given that it's only 1 HP—seems torque's the answer.

   I bought my saw thru a newspaper ad—$900, including original manual, dado blades, and moulding head and cutters. I was the first person to call, beetled over to the seller's house, and negotiated as the phone kept ringing in the background!

   It belonged originally to the lead carpenter for the Seattle School District, and is the same model I learned on in shop class. I believe they were sold to schools in large numbers at that time.

   Anyway, it's the one tool I'll never part with. The only modification I've made is to replace the original Jet-Lock fence with a Biesemeyer—a well worthwhile investment!

5. 
   cheakamus | Jan 15, 2003 08:54pm | #12

   Thank-you, DJK, for your detailed reply. I'm printing it out to keep with the other documentation for my saw. There's actually nothing wrong with my saw (touch wood!) at the moment—it was another, earlier post about a motor problem that made me start thinking I ought to at least maintain the brushes on my motor. I'm afraid commutators are a bit beyond me at the moment, athough I do have a lathe. Do you know of any books that might be useful to learn about this stuff? Until I know more, I don't feel confident enough to do all you recommend, but I think I can handle checking the brushes and replacing them if necessary. What constitutes needing replacement? Is it simply that they're worn down signifcantly?

2. 
   cheakamus | Jan 15, 2003 08:47pm | #11

   You're right! When I posted my message last night, I didn't bother to go all the way to the basement to look at the motor, but today I see it has two elliptical cover plates, which must be for the brushes, and an end-cap for access to the motor's guts. It seems pretty easily accessible (unfortunately, I don't have the original cast-iron cover).

   Can you (or anyone) recommend a good book on motors for someone without much experience who's willing to learn? I understand house wiring pretty well, but I remember looking for information on motors when I was installing a 220 circuit for this saw and coming up with precious little (that I could understand) at the library—it was all either too simple or too complicated.

   Many thanks. I appreciate your response!

1. 
   dmt | Jan 15, 2003 09:28pm | #14

   You might want to visit the NEMA (National Electrical Manufacturers Association) website and download a publication called NEMA Standards Publication Condensed MG 1-2002 Information Guide for General Purpose Industrial AC Small and Medium Squirrel-Cage Induction Motors (http://www.nema.org). It is located under "Standards." This is a condensed version of NEMA Standards Publication MG1 Motors and Generators used by the motor industry.

   The Electrical Apparatus Service Association (EASA) represents motor repair shops. They have some good literature (a lot of based on NEMA) that might be useful.Regards,

   Dan T.

2. 
   TKanzler | Jan 15, 2003 09:52pm | #15

   Maybe Electric Motor Repair, by Robert Rosenburg (sp?).  If covers RI motors, such as yours, along with more typical types of AC and DC, whereas NEMA MG-1 is limited to AC induction motors.  And you are right, the simple books are useless, and unless you're in the business, the good ones can be too difficult to follow.  But do check out the MG-1 standard.  You could gain some understanding of basic parameters like operating characteristics and nameplating requirements.Be seeing you...

3. 
   dmt | Jan 15, 2003 11:35pm | #16

   "... whereas NEMA MG-1 is limited to AC induction motors."

   You are incorrect. NEMA MG1 is about 565 pages in length and covers manufacturing and performance requirements for AC and DC motors and generators of all types ($175.00). The Condensed MG1 is about 60 pages (and is free) but is limited to AC induction motors because those are the most popular.

   Regards,

   Dan T.

   Edited 1/15/2003 3:36:43 PM ET by DanT

4. 
   TKanzler | Jan 15, 2003 11:49pm | #17

   I last saw my only copy about 10 years ago.  But I only work with AC induction motors, and never paid any attention beyond that type when I did have it.  I stand corrected.Be seeing you...

5. 
   DJK | Jan 16, 2003 01:29am | #18

   Not all parts are cheaper, but some are , you need to check. Go to http://www.acetoolrepair.com and you should be able to check the Delta Canada prices. I order from the Delta factory center in Guilph, ON and have them shipped to my father-in-laws. Pick them up when we go for the weekend. Needed an arbor pulley for my "42 Unisaw, $92 here and $79 Cdn. plus the exchange. I do the same purchasing FS Tool saw blades. With my discount and the exchange I end up paying U.S. dealer prices.

   About the RAS motor, email me directly and I will give you the number of a friend who has an extra motor. He has a RAS and extra motor sitting in the barn waiting for a buyer.

   Dave Koury

   Warren, MI

6. 
   cheakamus | Jan 17, 2003 02:55am | #22

   Thanks, TDKPE, that sounds just like what I'm looking for.

   Thanks to you too, Don. I'll definitely check out the nema site and try to get hold of the condensed handbook.

2. 
   wcperry4 | Jan 16, 2003 03:32am | #21

   Point taken.  Thanks for your response.

4. 
   booch | Jan 17, 2003 03:36am | #23

   Find a Motor repair shop. They'll make the diagnosis and repair for a reasonable amount of money. I had a Craftsman 1.5 Hp 220 / 120 v that crepped out and I took it in for a quick diagnosis 20 bucks and an air hose to the thermal OL and all has been well for a decade.

   As for yours. Probably some alignment or broken brush mounting. Sparking is normal for the first few hours of new brush installation but yours sound s more severe. Don't screw it up further by whacking it with a hammer or some other witch doctor repair method. The motor repair centers (should be 20 in your phone book) will sniff it out quickly. Beyond that if it is toast they will be able to rewind (not needed here) replace bearings? or even pull an orphan off of the shelf and sell it to you cheaper than the one with the grey paint.

   Best of luck. You could crack it open and look for yourself. I would, but then again I wouldn't jeopardize my life by doing anything dumb. It could be full of maple dust or june bugs for all you know.

   Jack of all trades and master of none - you got a problem with that?
1. 
   wcperry4 | Jan 18, 2003 05:13am | #24

   Thanks for the response and the tip.  Your's is the best idea I've heard.  Maybe some hope for it yet.  Thanks again.

1. 
   Sancho | Jan 18, 2003 07:23am | #25

   Bill you can get a 2hp baldor for about 240 bucks through tool crib of the north..just a idea 

   At Darkworks  Customer satisfaction Job One..Yea yea were all over it , I got my best guys on it.........

1. 
   wcperry4 | Jan 19, 2003 01:31am | #26

   Ron,

   That brings up a question I've been pondering.  I haven't removed the original motor yet so I'm not real sure how it's mounted but a friend of a friend works for a company that sells motors.  He said he could probably get me one at cost.  I wonder how the mounting hardware would match up?  Any ideas?

1. 
   booch | Jan 20, 2003 05:28pm | #27

   Sorry to interlope again but industrial motors are generally "NEMA" sized. The info may be on the nameplate. POS "Motorized 10" non belt driven saws may be an exception. Appliance motors are generally exempt from the standards. (clothes driers, Kitchen fans, etc) To get a UL rating on them you have to get the entire assembly approved. NEMA & UL ratings are not related directly but they are parallel approval systems.

   In short you are looking for a frame size. There are standards for mounting.Jack of all trades and master of none - you got a problem with that?

2. 
   wcperry4 | Jan 21, 2003 01:47am | #28

   Sounds good.  Thanks for the info.

3. 
   Sancho | Jan 21, 2003 06:50am | #29

   Cant say for sure but I do know a guy who has one mounted on his crapsman and works great 

   At Darkworks  Customer satisfaction Job One..Yea yea were all over it , I ll have it done by next Tuesday Oh yea I need another draw.........