Startup / Shutdown Sound of JET XACTA - Woodworking Talk - Woodworkers Forum
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post #1 of 18 Old 06-06-2017, 10:58 PM Thread Starter
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Question Startup / Shutdown Sound of JET XACTA

Does the table saw have a break? I am just wondering if the shutdown sound it makes at the end is normal. Here is short video I posted on YouTube:


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post #2 of 18 Old 06-07-2017, 10:45 AM Thread Starter
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Really... no one?

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post #3 of 18 Old 06-07-2017, 02:32 PM
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It has a break on it, I think it sounds normal, but that would be relative as I have no experience with this table saw. It sounds a little "rougher" than the breaks I've heard on the SawStop and Powermatic. But this could also be because its new and the brake is unused, its hard to say.
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post #4 of 18 Old 06-07-2017, 02:37 PM Thread Starter
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Originally Posted by Techsniffer View Post
It has a break on it, I think it sounds normal, but that would be relative as I have no experience with this table saw. It sounds a little "rougher" than the breaks I've heard on the SawStop and Powermatic. But this could also be because its new and the brake is unused, its hard to say.
Ok. Thanks. I figured it was a brake but I couldn't find anything in the manual or online about it.

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post #5 of 18 Old 06-07-2017, 02:43 PM Thread Starter
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Just got off the phone with one of JET's technicians and he said that this machine does have a "centrifugal switch" which acts as a brake. Therefore, the noise is normal by design.

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post #6 of 18 Old 06-07-2017, 02:58 PM
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Just got off the phone with one of JET's technicians and he said that this machine does have a "centrifugal switch" which acts as a brake. Therefore, the noise is normal by design.
Yeah most people just call it a brake =P

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post #7 of 18 Old 06-07-2017, 03:08 PM
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Sorry, I replied before work this morning, but must not have actually submitted it. That sound you hear is pretty normal for this type of motor when the centrifugal switch clicks off. With the switch off and the motor still spinning, there's an electrical interaction occurring with the capacitors known as regeneration....it's what causes that slight shutter.

Here's a link to a nearly identical question recently on another forum for a similar saw.
Saw video


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post #8 of 18 Old 06-07-2017, 03:46 PM Thread Starter
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Here’s another video of the inside of the machine when starting up and shutting down. As you can see, the belt “jumps” at the end which I guess is the centrifugal switch/brake.


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post #9 of 18 Old 06-07-2017, 06:35 PM
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That looks normal too. The centrifugal switch isn't really a brake, but the whole interaction with the caps can seem like one.
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post #10 of 18 Old 06-07-2017, 09:05 PM
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Only thing that worries me is how much that belt jumps, doesn't look like it would take too much for that thing to pop off or become misaligned. Not sure if that is normal, but it caught my eye.

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post #11 of 18 Old 06-08-2017, 04:08 AM
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Only thing that worries me is how much that belt jumps, doesn't look like it would take too much for that thing to pop off or become misaligned. Not sure if that is normal, but it caught my eye.
Seconded, that belt looks loose. Im also wondering about the time to spin down that blade, it seems like its taking too long for something that supposed to have a 'brake' (i realize a centrifugal switch isnt actually a break, but clearly the jet tech doesnt). It feels like my Delta saw, which is brake-enabled, stops way faster, <5 seconds. Not a sign of a problem with yours of course, but that spin-down time and the time it takes the switch kicks in seems long

That switch kicking in sounds pretty 'thunky' to me. Again, not necessarily a problem, just sounds loud compared to other motors ive used

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post #12 of 18 Old 06-08-2017, 04:29 AM
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I once had a brake on a Craftsman saw which wasn't very aggressive. It just put a little friction to slow the blade to stop about twice as fast as if there was no brake. That would be alright in my book. Having one very aggressive I don't think I would put up with. I think eventually someday you will shut the saw off and the sudden stop will loosen the arbor nut and the blade will come loose causing the blade to hit the throat plate.

I've had the electricity suddenly cut off and then back on causing the blade to come loose.
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post #13 of 18 Old 06-08-2017, 11:14 AM Thread Starter
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According to others in another forum who have the same saw, it doesn't have anything to do with the belt. Supposedly, "some" motors do this and some don't. I just depends on which one you got. What is actually happening is that (when the saw is shutting down) the centrifugal switch contacts close, the capacitor will dump its charge across the windings which cause (sometimes violet) shudder. The proposed solution is to add a "bleeder resistor" to bleed off the capacitor charge before shutting off the motor. Regardless, I feel like it is a major flaw in the design of the motor.

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post #14 of 18 Old 06-08-2017, 02:46 PM
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According to others in another forum who have the same saw, it doesn't have anything to do with the belt. Supposedly, "some" motors do this and some don't. I just depends on which one you got. What is actually happening is that (when the saw is shutting down) the centrifugal switch contacts close, the capacitor will dump its charge across the windings which cause (sometimes violet) shudder. The proposed solution is to add a "bleeder resistor" to bleed off the capacitor charge before shutting off the motor. Regardless, I feel like it is a major flaw in the design of the motor.

Actually all split phase motors will do that but not all quite as much. What is happening is the start windings generate back electromagnetic force or EMF as does the run windings when the centrifugal switch closes the forces oppose each other and that is what you are hearing. Since it just a capacitor run motor the forces are greater. If it was a permanent split capacitor motor (PSC) the braking action is much less as the windings are tied to each other through the run capacitor
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post #15 of 18 Old 06-08-2017, 02:53 PM
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You belt may be a little tight, but it looks about right, you have a decent sized chunk of iron spinning, and when the stitch shuts it is breaking pretty hard so something has to give a little, or something will give over time

"Serpentine" belts are great on somethings, and on others they aren't so great. They really ought to have a spring loaded idler to take up that slack.If you tighten the belt too tight it will probably cause continuous vibrations. The grooves in a a ploy belt aren't as deep as a regular V belt so they are less forgiving. Most sheaves have a little run out, and that will be amplified by being too tight
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post #16 of 18 Old 06-08-2017, 05:39 PM Thread Starter
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You belt may be a little tight, but it looks about right, you have a decent sized chunk of iron spinning, and when the stitch shuts it is breaking pretty hard so something has to give a little, or something will give over time

"Serpentine" belts are great on somethings, and on others they aren't so great. They really ought to have a spring loaded idler to take up that slack.If you tighten the belt too tight it will probably cause continuous vibrations. The grooves in a a ploy belt aren't as deep as a regular V belt so they are less forgiving. Most sheaves have a little run out, and that will be amplified by being too tight
Thank you. That makes perfect sense. I just won't worry about it then. I want to try shutting it down without the blade on it... just for peace of mind that it doesn't do this when that "big chunk of metal" is attached.

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post #17 of 18 Old 06-09-2017, 11:17 AM
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Thank you. That makes perfect sense. I just won't worry about it then. I want to try shutting it down without the blade on it... just for peace of mind that it doesn't do this when that "big chunk of metal" is attached.

- Wil

My Unisaw is one of them that does it intermittently, mostly a smooth coast down but every once in a while it will be noisy, ain't nothing to worry about
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post #18 of 18 Old 06-09-2017, 02:29 PM
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My Unisaw is one of them that does it intermittently, mostly a smooth coast down but every once in a while it will be noisy, ain't nothing to worry about

It pretty much depends on how much "in phase" the sine wave is with each other

How long do you think a 60 CPS electric sine wave is?








Between 2300-2800 miles. It depends on who is figuring the speed of electricity, the consensus is about 2/3 of the speed of light so it would be pretty close to 2500 miles

Kind of odd if you think about it, when the front of the wave hits your machine, the rear is still in the generator and probably not even formed yet

Some deep thinking for you LOL
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