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Replaced old saw switch and have little torque

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Forum topic by TheThom posted 07-02-2011 05:36 AM 3653 views 0 times favorited 33 replies Add to Favorites Watch
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TheThom

27 posts in 1989 days


07-02-2011 05:36 AM

Hello,

First time posting here. I recently tried to upgrade the fence on my cruddy Delta saw (cheap one given to me by parents years ago). I bought the Accusquare system, but the saw was too cruddy to install it on (no holes to mount it).

I turned to craigslist and bought an old Craftsman table saw (I think from ~1982ish – found one like it on owwm). I decided to make a custom table saw cart/table with a combined router table using the accusquare fence for both.

Anyway, the power switch from the saw was on the side and I tried to re-mount.replace it to the front. First I used this switch from Grizzly

http://www.grizzly.com/products/110V-Magnetic-On-Off-Switch/H8240

but the saw had almost no real power. a test piece of plywood stopped the blade immediately. I reviewed the specs and it turns out that this switch is only rated for 1/2 HP and my saw is 1 HO (stupid, I know). So I bought this one from Grizzly that could go up to 2HP on 110 volts.

http://www.grizzly.com/products/110-220V-Paddle-On-Off-Switch/H8243

I just finished installing it and i have the same results. The blade turns, but has no real power. Either I screwed up the wiring, there was a crucial component/converter in the original switch box or somehow when using my compressor to clean the motor (air brush style), I killed the motor, because it worked fine before.

Anyways. Please help if you have any ideas. As you can tell I’m a novice woodworker and a total beginner at refurbishing tools

-- "Everything should be made as simple as possible, but not simpler" -Albert Einstein


33 replies so far

View lew's profile

lew

11348 posts in 3223 days


#1 posted 07-02-2011 05:42 AM

Did you try putting the original switch back in?

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View TheThom's profile

TheThom

27 posts in 1989 days


#2 posted 07-02-2011 06:44 AM

Unfortunately, the original wiring and connectors were pretty mangled and I can’t get them back on.

-- "Everything should be made as simple as possible, but not simpler" -Albert Einstein

View EEngineer's profile

EEngineer

1061 posts in 3081 days


#3 posted 07-02-2011 07:44 AM

I used a switch in that same series (no paddle) on my Sears Craftsman 1 HP motor and it actually improved my saw’s power. I think the original rocker switch that Sears used was marginal for that much motor.

One clue here is when using my compressor to clean the motor. More than once I have read of people blowing dust into the contacts on the centrifugal switch. However, this should cause the motor to have trouble starting. Maybe it is possible that you disturbed the dust so that the centrifugal switch never disengages to remove the starting cap from the circuit?

I also have to suspect extra resistance in the electrical connections. Did you replace only the switch? Or did you put a new cord and plug on it too? 18 gauge (like most extension cords around the house) is simply not enough for a 1HP motor. 14 gauge is marginal. I put 12 gauge on mine when I rewired it simply because I didn’t want the last leg of the wiring to be a limiting factor.

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

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TheThom

27 posts in 1989 days


#4 posted 07-02-2011 04:27 PM

I used the original power cord. It worked on 110 before. I don’t know why that would change.

EEngineer: I think you might be onto something. The motor hums for about a half second and then starts turning (slowly). I’ll fiddle with it a bit, try to clean the contact points, and see if that helps.

Thanks for the ideas. I really appreciate the help.

-- "Everything should be made as simple as possible, but not simpler" -Albert Einstein

View EEngineer's profile

EEngineer

1061 posts in 3081 days


#5 posted 07-02-2011 11:50 PM

The motor hums for about a half second and then starts turning (slowly).

Now that sounds like a classic starting cap problem. There very well could be dust in the contacts of the centrifugal switch that is keeping the cap from being switched in at 0 speed. And it could be that the starting cap picked this precise moment to die. But I’d bet on sawdust…

Good luck!

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

View MedicKen's profile

MedicKen

1610 posts in 2930 days


#6 posted 07-03-2011 12:13 AM

It sounds like you only have half the power. 110V on 220V circuit. The slow starting could be the capacitor if it has one. Does the motor have brushes? How old is the motor? Do you have the model number for the motor?

-- My job is to give my kids things to discuss with their therapist....medic20447@gmail.com

View TheThom's profile

TheThom

27 posts in 1989 days


#7 posted 07-03-2011 01:19 AM

I think EEngineer is on the right track. Since the last time it ran and now I blew a ton of air around and changed the switch.

I’m trying to attach pics of the motor. The saw is from ~1980ish

Motor part no 62626 Mfg Model: KS48DC-206 Volts 120

Is there a good place to find info on motor workings/details?

This is the motor casing

This is the right side of the motor casing when disassembled

The left side when disassembled

The inside of the left portion. Here’s where I get confused. I don’t see any switch (i.e. centrifugal switch). The only thing inside the casing is a round spring/washer

Also, when I tighten the screws to put the casing back to together, I can only get the arbor to turn if I leave the screws loose – when I lightly snug them, it won’t turn.

With the screws loosened when I turn it on, it buzzes and I can’t turn the arbor. Presumably because the magnet is engaged and the middle portion is off center.

Thoughts?

I sincerely appreciate your help. Clearly I have no idea about electric motors. I consider myself to be a bright guy, but this project has humbled me to date. Help on this site is the only thing keeping from listening to my wife and giving up :-)

-- "Everything should be made as simple as possible, but not simpler" -Albert Einstein

View TheThom's profile

TheThom

27 posts in 1989 days


#8 posted 07-03-2011 02:09 AM

Also – it’s worth mentioning that there was a bout 15 gallons of sawdust inside the motor (give or take 14.9 gallons).

-- "Everything should be made as simple as possible, but not simpler" -Albert Einstein

View MedicKen's profile

MedicKen

1610 posts in 2930 days


#9 posted 07-03-2011 02:17 AM

HOw do the bearings feel? Are they noisy? What brand is the motor? I might be able to get some literature on it

-- My job is to give my kids things to discuss with their therapist....medic20447@gmail.com

View TheThom's profile

TheThom

27 posts in 1989 days


#10 posted 07-03-2011 02:26 AM

It turns pretty smooth. I don’t think the bearings could be any smoother (at least not with me doing them). It’s an old Craftsman and I believe at the time this saw was made, that Emerson made the motor, but I can’t find a brand on it.

-- "Everything should be made as simple as possible, but not simpler" -Albert Einstein

View TopamaxSurvivor's profile

TopamaxSurvivor

17677 posts in 3144 days


#11 posted 07-03-2011 07:18 AM

Does it have a capacitor case on the outside? Capacitor might be the problem??

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View EEngineer's profile

EEngineer

1061 posts in 3081 days


#12 posted 07-03-2011 03:05 PM

What I expected was a belt drive table saw with a motor that has a separate can on the side (like a tumor) that contains a starting capacitor. This looks like a direct drive – i.e. motor shaft is directly attached to the arbor – correct?

Here is some information from Sears about that motor wiring. It is a capacitor start RI motor but it uses a potential relay to switch out the starting cap instaed of a centrifugal switch inside the motor itself. I hope you didn’t throw the “switch” box away. Far from being just a simple switch, it included a starting relay and the starting capacitor in it. You can’t replace this assembly with just a simple switch. Does this look anything like the control box on your saw?

There must be something wrong with the mechanical assembly if you cannot tighten the casing screws. You’ll note that the link I gave you above also has an exploded drawing of the motor assembly. I suspect that the bearing on the end opposite to the arbor is not seating properly in the housing. If you can’t turn the shaft freely, then the rotor is binding against the stator and it isn’t going to turn with power on either. No need to give up yet, motors are fairly simple mechanical beasts. You say the bearings are good and those are the single biggest cause for mechanical failure in motors.

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

View TheThom's profile

TheThom

27 posts in 1989 days


#13 posted 07-03-2011 04:08 PM

You nailed it EEngineer. I tried to post a pic of what was included in the switch bos with my first post, but ran into technical difficulties. Here it is:

So, it turns out that I didn’t need to disassemble everything, if I would’ve just posted that pic? Awesome. It’s gonna test me to see if I can get it all back together.

Also, that diagram is helpful, but isn’t a wiring diagram. Do I need to buy a simple switch and wire it the way it was, or is there a way to incorporate the relay and capacitor with the new switch?

You’ve been really helpful and I appreciate it!

-- "Everything should be made as simple as possible, but not simpler" -Albert Einstein

View TopamaxSurvivor's profile

TopamaxSurvivor

17677 posts in 3144 days


#14 posted 07-03-2011 09:03 PM

I have never seen one of those before. If the potential relay is bad, you can wire in a manual start switch ;-))

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View SCOTSMAN's profile

SCOTSMAN

5839 posts in 3053 days


#15 posted 07-03-2011 09:17 PM

Yes your saw will only idle without the extra power the capacitor gives it.Put it back and you should be fine. Alistair

-- excuse my typing as I have a form of parkinsons disease

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