Delta Table Saw problem

Got a bit of a problem here with my Delta 10″ Table Saw. Recently I was doing a dado cut in some oak and the motor just died in the middle of a cut. This happened once before (the drive belt had broken) but I could hear the motor. This time, nothing. A quick inspection of the brushes confirmed that they had worn out big time. I happened to have a spare set of brushes so I set about installing them. That took the rest of a Sunday afternoon. I didn’t have a chance to get back to my shop til this past Saturday. When I started the saw, I saw the motor sparking. At first I didn’t really pay it any mind and I performed a rip cut in another piece of oak. Funny thing was I noticed the saw stopped at the end of the cut. Funny because I hadn’t turned off the switch. A quick trip to the electric panel confirmed I had tripped the breaker. After resetting it I powered up the saw and it immediately tripped the breaker again. At this point I decided to pull the brushes again and discovered they are over half gone and really scarred. Any ideas about what my problem is? Am I going to be replacing a motor? Delta has changed the motor since my saw was purchased and they want $195.00 for the new one.

Replies

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

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.

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.

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.

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 !)

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.

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.

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.

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

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.

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!

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?

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!

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.

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.

". 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

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.

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

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.

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.

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

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.

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?

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?

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.

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