Delta TS motor is now "slow start"

Delta 36-725, about 4 years old. Given that it was on sale, and my 10% discount, if this saw melted into a puddle of slag today, I've already gotten my money's worth for how much I use it. Up until now, it was a "pretty fast start" motor, would take less than 1/2 second to come up to speed, couldn't even notice the start up, really. Now it takes about 2 seconds to spin up to speed, and it's really noticeable. Is this something as simple as a start capacitor? Again, for the price paid, this is not worth taking it to an "Authorized service center" and waiting 3 years for them to decide to fix it. I use it weekly, I'll buy another one if it's that far gone.

Yes:

• Occurs no matter what blade is in it
• It is plugged to the same, independent 120V circuit with the same cord
• The dust port/shroud is clear of dust
• All my other circuits, the shop sub panel, and the main panel, all test as they did when I passed my final electrical 2 years ago.
• Occurs no matter what circuit in the shop I move the cord to (direct from saw to outlet no extension)

No:

• There have been no changes to any circuit. I haven't even changed a bulb since my final inspection
• I am not "forgetting" that there is a piece of 3 inch hard maple on the saw. THere is no wood in the blade on start up.
• There is no excessive heat on the motor after 1 minute or 20 minutes of run time

Is a start capacitor something that is cheap and easy to replace? I'm thinking if not, I'll use it like I stole it 'till it melts.

I would take the motor out and check the bearings. If all is okay, I'd try a new start cap.

Mike

Start caps usually fail open. They may first fail shorted, but then they proceed to overheat, partially melt (yielding a lovely smell in the process), and end up open. When they are open, the motor usually just won't start. Often you can get it to start by manually giving it a spin.

So it's unlikely your start cap has failed open. Caps can change value, which could cause your symptoms, but it's not that common.

I'd start by removing the belt(s) and making sure the arbor spins smoothly and freely without any "bad bearing" noise.
Then I'd blow out the motor with compressed air, especially the area opposite the shaft, where the centrifugal start switch will be. You may have to partially disassemble the motor to do this, especially if it's a TEFC motor. Dirty start switch contacts can limit the start current, leading to slower starting.

If none of that helps, you might as well replace the start cap. It's easy and cheap to do.

Sounds like everybody's on the right track, but I just thought of the switch- strange things can happen if they get packed with too much sawdust. A quick look inside/cleanout certainly won't hurt.

Jeff

Quote:

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Originally Posted by Paul F Franklin

Start caps usually fail open. They may first fail shorted, but then they proceed to overheat, partially melt (yielding a lovely smell in the process), and end up open. When they are open, the motor usually just won't start. Often you can get it to start by manually giving it a spin.

So it's unlikely your start cap has failed open. Caps can change value, which could cause your symptoms, but it's not that common.

I'd start by removing the belt(s) and making sure the arbor spins smoothly and freely without any "bad bearing" noise.
Then I'd blow out the motor with compressed air, especially the area opposite the shaft, where the centrifugal start switch will be. You may have to partially disassemble the motor to do this, especially if it's a TEFC motor. Dirty start switch contacts can limit the start current, leading to slower starting.

If none of that helps, you might as well replace the start cap. It's easy and cheap to do.

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Just an added comment on Paul's suggestion. Sometimes a bearing will give problems when there's a belt on, pulling the shaft to one side. So check the bearings carefully. If it was me, I'd just take it out and replace the bearing - it's not really a hard job and you'll have the comfort of knowing you have fresh bearings in the motor.

Mike

Replace bearing....which one, and doesn't a bearing replacement call for specialized tools? Bearing press, micrometer....

you stated no excessive heat so try replacing the start capacitor THEN decide next step
have a DeWalt radial arm saw that acts that way since new (1980?), change the capacitor and all good for a few more years
Ron

Quote:

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Originally Posted by Ron Selzer

you stated no excessive heat so try replacing the start capacitor THEN decide next step
have a DeWalt radial arm saw that acts that way since new (1980?), change the capacitor and all good for a few more years
Ron

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Ron makes a good point. Replacing the start cap is easy and cheap so do that first.

As far as the bearings, the most likely one to fail is the one on the front of the motor, where the pully is. But I'd always replace both while you have the motor apart. There are some special tools to pull bearings that make the job easier. You sound hesitant about taking on that job so you might take the motor to a place that is experienced in doing that.

Mike

[I didn't look up that saw, I just assumed the motor was an induction motor. If it's a cheap saw, it could have a universal motor in it. In that case, it would not have a start cap. Is the motor an induction motor?

If it's a universal motor, I'd suspect the brushes. Change those before you do anything else (if it's a universal motor). The fact that someone described the motor as being "13 amps" would lead me to believe it's a universal motor. Induction motors are usually specified in HP.]

Can't find many good things said about this saw. Nice details on this link. https://forums.woodnet.net/showthread.php?tid=7351558

This could be bad bearings in the saw arbor. Easy to decide, remove the belt and spin motor and arbor by hand.

If it's the motor and you really don't want to mess with it, buy a new motor. You can then risk a potentially terminal 'exploration' of the old motor.