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Friend gave me a dewalt dw746 tablesaw with blown motor

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Forum topic by gardentiger posted 04-11-2011 09:56 PM 6954 views 0 times favorited 14 replies Add to Favorites Watch
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gardentiger

58 posts in 2433 days


04-11-2011 09:56 PM

I can order an oem motor for 380.00. However, was wondering if you guys had any ideas about purchasing a used motor or an aftermarket brand motor???


14 replies so far

View Bertha's profile

Bertha

13003 posts in 2156 days


#1 posted 04-11-2011 10:03 PM

I don’t know much about DeWalt motors but you’re in the Baldor prices at $380.00. You’ll get some good advice below.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

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knotscott

7210 posts in 2838 days


#2 posted 04-11-2011 10:40 PM

Does that saw take a proprietary frame? If so, I’d think you could have the original motor repaired for less than $380. If it takes a standard NEMA 56 frame there are loads of appropriate motor options for a 1-1/2hp motor for well < $380.

Can you take a good pic of the motor and mounting system?

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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knotscott

7210 posts in 2838 days


#3 posted 04-12-2011 01:07 AM

I Googled some pics of the DW746’s motor…unfortunately, it looks to be a proprietary setup to me, so your options are to repair it or to buy an OEM replacement. Before buying a new motor for $380, I’d check to see what a repair shop has to say. You might even be able to find a used 746 that you could pluck the motor from and sell the extra parts. Best replacement price I’ve found is from Toolpartsdirect for $374.


-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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mcase

446 posts in 2592 days


#4 posted 04-12-2011 02:01 AM

Have to agree with Knotscot, that looks proprietorial alright. Well there’s a couple of ways of looking at – its a way over priced motor that is obviously quite capable of burning out. OR the saw retails for over a grand and for less than four yur up and running. Honestly, I would worry about continually replacing these motors. Thats’ how it went on my old bottom level Delta hybrid.

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knotscott

7210 posts in 2838 days


#5 posted 04-12-2011 02:20 AM

If you’ve got a friend who can weld, maybe they could rig up a mount on the end of that extension for a NEMA 56 frame. Then you could spend $200 on an off the shelf motor, or less for a used one, and would never have to buy another proprietary motor for it.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View EEngineer's profile

EEngineer

1061 posts in 3076 days


#6 posted 04-12-2011 01:19 PM

How certain are you that the motor is blown? That looks like a capacitive start induction motor (the large “tumor” on the body of the motor looks like a starting capacitor). I have fixed a few of these by replacing the cap or, more rarely, repairing the centrifugal switch inside the motor that controls the starting cap.

Googling also reveals some power switch problems on that model saw. Make sure voltage is getting to the motor.

Induction motors are hard to kill. I would check a lot of other things before I gave up and ordered a new motor.

-- "Find out what you cannot do and then go do it!"

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gardentiger

58 posts in 2433 days


#7 posted 04-12-2011 02:39 PM

He said the motor smoked. He then switched it back to 110 and it wouldn’t start at all.

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gardentiger

58 posts in 2433 days


#8 posted 04-12-2011 02:51 PM

EEngineer, I am not an engineer. Could you give me some ideas of things to check??

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EEngineer

1061 posts in 3076 days


#9 posted 04-12-2011 04:09 PM

He then switched it back to 110 and it wouldn’t start at all.

This is a red flag. Check the wiring on the motor. Most motors I have worked with have the wiring to change from 110 to 220 just under a plate held by screws on the end of the motor. There should be a wiring diagram for 110 and 220 on the back of that plate. If he screwed that up, motor will not start. I would do this before trying anything else. The diagrams are usually pretty clear

As far as a bad switch goes, check with a voltmeter to make sure that voltage is getting to the motor from the switch. Again, remove the plate at the end of the motor, disconnect the incoming wires from the motor wires and use a voltmeter to make sure that voltage is there when switch is ON.

If the motor hums but will not turn, this is likely a bad cap or centrifugal switch. REMOVE THE BLADE BEFORE TRYING NEXT STEP! If motor hums but will not start, try turning the shaft by hand; if it is a bad cap, you may be able to start it like this.

If the motor doesn’t even hum, check for an overload on the motor. This is usually a red button on the motor itself that trips under overcurrent or overtemperature on the motor and must be pressed before motor will run again.

-- "Find out what you cannot do and then go do it!"

View EEngineer's profile

EEngineer

1061 posts in 3076 days


#10 posted 04-12-2011 04:24 PM

Here is a link to wiring diagram that seems to apply to your saw.

-- "Find out what you cannot do and then go do it!"

View dbhost's profile

dbhost

5604 posts in 2694 days


#11 posted 04-12-2011 04:31 PM

I passed one of those up on Craigslist a couple of weeks ago due to a bad motor… The guy wanted too much and it cost too much to fix…

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View knotscott's profile

knotscott

7210 posts in 2838 days


#12 posted 04-12-2011 06:03 PM

Checking the cap cans as EE suggests is 90 second job and is worth a look. There should be obvious signs of something scorched or blown up if they’re bad. His suggestions to check the wiring and voltage to the motor are also excellent. Any chance there’s a reset button anywhere on that saw?

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Howie's profile

Howie

2656 posts in 2385 days


#13 posted 04-12-2011 07:33 PM

Frankly this is another reason I quit buying Dewalt stuff. Any repairs you pretty much have to use their overpriced parts.
I think I would at the very least(after checking what some of the others above suggested) see if it can be rebuilt and how much.

-- Life is good.

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gardentiger

58 posts in 2433 days


#14 posted 04-12-2011 07:42 PM

much thanks, gentlemen and ladies??

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