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View Full Version : Another motor start capacitor craps the bed



Paul Girouard
06-09-2012, 12:01 PM
Third one in six months, the original one lasted 18 years or so.

So what else could be wrong that's causing these things to fry / leak out their oil?


http://i21.photobucket.com/albums/b299/PEG688/10Juky2011.jpg

Syed
06-09-2012, 12:12 PM
Have some safety margin on working volts and use with the next higher rating.

George Jung
06-09-2012, 12:31 PM
Either they're 'not making them like they used to' - or you've got a problem in the circuitry, right?

Paul Girouard
06-09-2012, 12:41 PM
Either they're 'not making them like they used to' - or you've got a problem in the circuitry, right?

That's my thinking. I asked the gal on the phone if they'd been having issues with the new caps, the Grizzly sales gal, of course she said , "Not that I've heard, but we'll gladly send a new one out to you."

I asked a Electrician who's trimming out one of our jobs , he said just hook it up , turn it one. Also the home owners a retired electrical engineer from Puget Power , our local PUD , he said the cap should store energy, when you turn on the saw it "fires off" the energy to get the motor spinning , then the cap recharges itself automatically and sit there ready for the next start cycle.

I've done nothing to the saw switch , or wiring from the panel in years. I have replaced the magnetic switch a couple of time in the past.


The oil leaks out of the capacitors when they go out.

So like you said it one or the other. I just asking if some one has other intel to pass on about what could be going on other than "they don't makum like they used to in China!" thinking.

Jim Mahan
06-09-2012, 12:45 PM
We had a tree limb come down on our power line. When the repair crew were finished reconnecting on the house side and we turned the power back on at the box, there was a bad ground on the pole side of the line which caused us to have only half the power at the box. It turns out that the connection at the pole must have been bad for a while causing us to have "dirty" power—fluctuations of voltage which are not good for electronic devices. We just recently got a check from the power company for four thousand dollars for reimbusement for damaged caused by dirty power.
Might you have a bad ground on your circuit?

Paul Girouard
06-09-2012, 12:49 PM
Wouldn't that effect more than just one electrical thing?

I'll check the ground wires / neutrals, etc are tight in the electrical panel and at the switch, good suggestion!!!! Bad grounds cause all sort of odd things!!

I'll report back what I find later today, THANKS!! I love this place!!

pipefitter
06-09-2012, 12:49 PM
Check the line voltage going in to make sure you still have 220v. Then check the motor start/running amps with an amp probe. Could also be a dirty, worn or weak centrifugal start switch as well.

Steve McMahon
06-09-2012, 12:59 PM
Stop buying the cheap made in China crap. You need to buy the expensive made in China crap.
( I work for a company that has an electric motor shop)

Paul Girouard
06-09-2012, 01:04 PM
Stop buying the cheap made in China crap. You need to buy the expensive made in China crap.
( I work for a company that has an electric motor shop)


LOL, OK then, where would I find the expensive made in China crap?

And here, Pipefitter, would the switches you referred to be located? The start switch is a magnetic type holds power on type swt.

SamSam
06-09-2012, 04:19 PM
I would suspect the motor also. It's not necessarily the old capacitor failed after 18 years and the new ones are crap, but that a problem in the motor burned out the old one and all subsequent new ones.

If the motors a ventilated type it could be dirty. Bad brushes maybe. Bad bearings overloading it. Scratch mark the covers then take it apart and look inside, clean it up, check the brushes.

Paul Girouard
06-09-2012, 04:23 PM
I would suspect the motor also. It's not necessarily the old capacitor failed after 18 years and the new ones are crap, but that a problem in the motor burned out the old one and all subsequent new ones.

If the motors a ventilated type it could be dirty. Bad brushes maybe. Bad bearings overloading it. Scratch mark the covers then take it apart and look inside, clean it up, check the brushes.


It's a big 3hp 220 motor , not something I'd be able to work on. I do blow it out on occasions , keep it clean.

SamSam
06-09-2012, 05:24 PM
It's a big 3hp 220 motor , not something I'd be able to work on. I do blow it out on occasions , keep it clean.
Blowing it out helps, but there's all sorts of nooks and crannies inside that accumulate dirt and cake up over the years.

The motor should not get hot in use. That's sort of hard to check now without a capacitor, but you can rope start it without the capacitor. Take the belt off, wrap a rope around the pulley (make sure it's the right way) give it a big yank like rope starting a gas mower and then turn on the power before it loses much momentum. Do not turn on the power until the rope is clear of the machine. That is real important. Of course that way you can't check the temp after running under a load, unless you can rope start it without taking off the belt.

I had a 1940s Boice Crane planer with a 3hp motor I had to start that way a number of times.

You have to get a new capacitor anyways, so it's best to get that and skip that rope start stuff.

Is there any provision for oiling the bearings?

Unhook the belt and see if it turns over real easily by hand, as it should. A quick turn by hand and it should keep rolling for several revolutions and gradually come to a stop. A little end for end play is allright, but it should not have any side to side play, bearing wise. Start the motor, then turn it off and listen for 'unsmooth' sounds, other than the brushes. It should take a pretty long while to coast to a stop.

Paul Pless
06-09-2012, 05:33 PM
If the motors a ventilated type it could be dirty. Bad brushes maybe. Bad bearings overloading it. Scratch mark the covers then take it apart and look inside, clean it up, check the brushes.Aren't most cabinet saw motors sealed?

SamSam
06-09-2012, 05:46 PM
If the new capacitor blows out in short order then it is likely that the centrifugal starting switch inside the motor is bad. The centrifugal starting switch disconnects the starting windings once the motor gets up to speed. If it is stuck closed the starting windings (which are wired through the starting capacitor) will never disconnect and the capacitor and/or the starting windings will eventually cook. Some motors are totally sealed up, which keeps debris out of the inside of the motor. But motors that are not sealed may offer some access to clean gunk out of the starting switch. If your motor has obvious vent holes in the end, you can try applying a shop vac to them to see if you can clean out the switch. Tapping the other end of the motor shaft with a ruber mallet while vacuuming may help to dislodge built up gunk. Thanks to David Maulik for sharing these tips on starter switch cleaning. His family owns a business that does motor repair and they often can clean the starter switch without opening the motor case.http://liutaiomottola.com/Tools/Motor.htm
(I had that in the above post, to listen for the cent. switch to cut out after about a second, but I took it out. )


Aren't most cabinet saw motors sealed? That would be handy. His is at least 18 years old, so I don't know. He mentioned Grizzly, so I'm thinking Chinese, basic electric motor, sealed costs more.

Paul Girouard
06-09-2012, 06:02 PM
http://liutaiomottola.com/Tools/Motor.htm
(I had that in the above post, to listen for the cent. switch to cut out after about a second, but I took it out. )

That would be handy. His is at least 18 years old, so I don't know. He mentioned Grizzly, so I'm thinking Chinese, basic electric motor, sealed costs more.


It's not sealed, I do blow it out. I just checked all the wires in the loop from the panel to the saw , all where nice and tight.

I'll go check the things in this post , check for play , it does spin easy with the belts on , I can turn the blade like is normal , but I'll take the belts off and check for end play and other things.

I don't think it was running hot , after this last starter crapped out I took off the outer case it's covered with right away , and the motor was warm but not so hot I couldn't touch it. I'm a whimp when it comes to hot stuff , so if I could touch it it would only be warm. My wife can handle out plates or pots that I can't even set down on the table fast enough , I think she has asbestos gloves built in!!

Thanks for the tips , I'll see what situation may fit my saw issue.

Steve McMahon
06-09-2012, 06:31 PM
LOL, OK then, where would I find the expensive made in China crap?

And here, Pipefitter, would the switches you referred to be located? The start switch is a magnetic type holds power on type swt.

Go to your local motor shop. A rule of thumb is that the bigger a capacitor is for the same rating, the better it is. btw - There are no brushes in that motor.
Start capacitors in a big single phase motor take a beating on an industrial / commerical application.

Paul Girouard
06-09-2012, 07:09 PM
Well the motor is sealed ,,,,,, sort of ,,,,

http://i21.photobucket.com/albums/b299/PEG688/001-14.jpg


I been blowing it out with the guard on , I don't think I've ever taken it off before.

http://i21.photobucket.com/albums/b299/PEG688/003-10.jpg

Those would be the starter cut out switches , I blew out thru every hole that dust came out of to the point where I wasn't getting any more dust.

I decided to hook up the old cap and see if she'd fire off . And it DOES!!! So what I'll do is wait for the new one to come in on Monday before I do any cutting.

I lubed the switches with a dry graphite , the switches worked easy by hand , and they where not to caked in dust. There was less dust in that area than in the terminal block in the first photo. BUT there was plenty of dust inside the bigger case so maybe the cut out switches where not working. When I turn it on and off now I can see the switches throwing due to centrifugal force , or so it seems.

http://i21.photobucket.com/albums/b299/PEG688/004-9.jpg

The last two photo's show the switch in the two positions , open and closed / off and running.

Thanks for the tips guys! Like I said for all the bad stuff that gets written here in the bilge there's nuggets of great info that gets pasted around. Best place on the net , IMO, WBF bilge!!

Thanks again Sam Sam and all you others that chimed in!! :ycool: :ycool:

pipefitter
06-09-2012, 07:25 PM
I lubed the switches with a dry graphite , the switches worked easy by hand , and they where not to caked in dust. There was less dust in that area than in the terminal block in the first photo. BUT there was plenty of dust inside the bigger case so maybe the cut out switches where not working. When I turn it on and off now I can see the switches throwing due to centrifugal force , or so it seems.


There is a set of contact points on the centrifugal switch. Some switches have the points suspended on a springy copper band that can become fatigued over time, along with the cadmium layer on the points wearing which will not let the points make an ideal contact. If you can, see if the contact points are pitted.

Once you get it all put back together or to where it will run, note if there is any significant spark coming from or from the area of this switch. I worked on electric motors for years mostly in the field. Believe it or not, the common piss ant helped fund my livelihood for their uncanny ability to get right between these contacts and wipe them out in short order, but dust will do the same. If the contact points are pitted or full of slag, clean them with a proper points file and if you want to go the extra step, polish with no less than 1200 grit wet/dry sandpaper.

Durnik
06-09-2012, 07:38 PM
Looks like dust did it again. Glad to hear the original cap is still good. They truly _don't_ make them like they used too.. ;-)

To clarify & for future visitors, this line
..then the cap recharges itself automatically and sit there ready for the next start cycle. is not quite the case. These caps in operation act as conductors.. essentially, an intentional short (low impedance). It is the current it sources, not the voltage it develops, which performs the work. That it _does_ develop a voltage is why it needs a higher PF.

This is why Syed's & Steve's comments/suggestions are so valid. The size of a cap is (roughly) directly proportional to Voltage, Capacitance & PF. Increase either one and the cap gets physically larger - more expensive &, in the case of an increase in Voltage or PF, less likely to fail. One of the few cases where 'Bigger _is_ Better'! ;-)

enjoy
bobby

PeterSibley
06-09-2012, 07:41 PM
Blowing it out helps, but there's all sorts of nooks and crannies inside that accumulate dirt and cake up over the years.

The motor should not get hot in use. That's sort of hard to check now without a capacitor, but you can rope start it without the capacitor. Take the belt off, wrap a rope around the pulley (make sure it's the right way) give it a big yank like rope starting a gas mower and then turn on the power before it loses much momentum. Do not turn on the power until the rope is clear of the machine. That is real important. Of course that way you can't check the temp after running under a load, unless you can rope start it without taking off the belt.

I had a 1940s Boice Crane planer with a 3hp motor I had to start that way a number of times.

You have to get a new capacitor anyways, so it's best to get that and skip that rope start stuff.

Is there any provision for oiling the bearings?

Unhook the belt and see if it turns over real easily by hand, as it should. A quick turn by hand and it should keep rolling for several revolutions and gradually come to a stop. A little end for end play is allright, but it should not have any side to side play, bearing wise. Start the motor, then turn it off and listen for 'unsmooth' sounds, other than the brushes. It should take a pretty long while to coast to a stop.
I take mine off and take them off to an electrician every couple of years. He usually swears and mumbles and cleans a tea cup of dust out .

Paul Girouard
06-09-2012, 07:43 PM
There is a set of contact points on the centrifugal switch. Some switches have the points suspended on a springy copper band that can become fatigued over time, along with the cadmium layer on the points wearing which will not let the points make an ideal contact. If you can, see if the contact points are pitted.

Once you get it all put back together or to where it will run, note if there is any significant spark coming from or from the area of this switch. I worked on electric motors for years mostly in the field. Believe it or not, the common piss ant helped fund my livelihood for their uncanny ability to get right between these contacts and wipe them out in short order, but dust will do the same. If the contact points are pitted or full of slag, clean them with a proper points file and if you want to go the extra step, polish with no less than 1200 grit wet/dry sandpaper.


Define significant spark.

You can see the orange flash in this photo , on the left side , that appears to be the contact point , the RH side does not appear to have a "point" unless it's been broken off. Should I see two flashes ? There is a flash , the camera can't catch it , to much delay and trigger slop or maybe it's the camera man , LOL , he's no damned good either!! LOL.

I think I should order a new switch to , just to be sure. What ya think??

http://i21.photobucket.com/albums/b299/PEG688/008-1.jpg

Steve McMahon
06-09-2012, 07:52 PM
It would be a great idea to replace the internal start switch while you have it apart. It looks like it is a really good design for ease of access.

pipefitter
06-10-2012, 01:20 AM
Define significant spark.

You can see the orange flash in this photo , on the left side , that appears to be the contact point , the RH side does not appear to have a "point" unless it's been broken off. Should I see two flashes ? There is a flash , the camera can't catch it , to much delay and trigger slop or maybe it's the camera man , LOL , he's no damned good either!! LOL.

I think I should order a new switch to , just to be sure. What ya think??

I would check the points first. There is only one set. You can manually trip the centrifugal actuator and get a look at the points. If they aren't all slagged up/fuzzy looking and nothing looks burnt, you can get another life or two out of it. Look to see if they make positive contact. If the points aren't making good contact, it will arc erroneously upon contact. I take being able to visibly tell for granted being I saw a lot of motors with and without this issue. If you can, watch a known healthy motor to see what the spark should kind of look like. It's hard to explain in text.

It's hard for me to see in the photo exactly what kind of switch you have. If it's just a switch that comes off with a set screw, not bad. Some are pressed onto splines and can be tricky to adjust if they are the type that need to be adjusted initially. It has to contact well and also disengage completely.

Paul Girouard
06-10-2012, 10:21 AM
I would check the points first. There is only one set. You can manually trip the centrifugal actuator and get a look at the points. If they aren't all slagged up/fuzzy looking and nothing looks burnt, you can get another life or two out of it. Look to see if they make positive contact. If the points aren't making good contact, it will arc erroneously upon contact. I take being able to visibly tell for granted being I saw a lot of motors with and without this issue. If you can, watch a known healthy motor to see what the spark should kind of look like. It's hard to explain in text.

It's hard for me to see in the photo exactly what kind of switch you have. If it's just a switch that comes off with a set screw, not bad. Some are pressed onto splines and can be tricky to adjust if they are the type that need to be adjusted initially. It has to contact well and also disengage completely.

There is a set screw on the shaft , it sort of shows in the last photo , and two or three small screws that appear to attach it to the motor housing , two wires one on each side that would have to be disconnected as well . I can't see the points area very well with it on the motor , and I haven't removed it yet due to fear that some thing like adjustment, small parts / springs / etc that may fly off as the switch is removed .

If the switch will just slide off and no small bits are going to fly around I'll pull it today to inspect it more closely!

There is a light metal "baffle" that flexes as you make and break the switch. I think it disengaging fully.

The saw starts sort of slow , but I'm using the old cap to fire it off. My thinking is leave whats in place until tomorrow when the new cap comes in , install the new cap , and watch how it starts with it with the covers off , so I can compare to the old cap start to the new .

If in a few months the cap goes out again , I'll order a new cap and switch at one time and replace both of them.

If I win the Loto before then , I'll get a new Saw Stop saw with a dado head adapter! Guess I'd have to buy a ticket to , unless you'd like to send me a few??? LOL.

Peter Malcolm Jardine
06-10-2012, 12:20 PM
I went to hook up my dust collector the other day... it hasn't had more than 50 hours use in the last two years... the *&$%^# motor wouldn't start... chinese 1 1/2 horse. Hums, but won't run, then trips the breaker. Grrr.

David G
06-10-2012, 02:10 PM
Squid,

Man... are you this hard on your other tools <G> How about friends & family? Girlfriends and wives?

I bought a Grizzly 8' Jointer many years ago. It came with the fence casting warped (twisted). I sent it back. They sent me a brand new one. Warped even more. Repeat twice more. Finally... a customer service guy asked me how badly the current one was twisted. I told him. He whispered into the phone, "I shouldn't tell you this, but I'd hang onto THAT ONE if I were you". I did. I thought they'd gotten better.

Paul Girouard
06-10-2012, 02:17 PM
David G: Normal use I'd call it. I'm thinking it isn't Grizzly's issue , but a learning curve about what needs cleaned .

Peter : Have you blown out the motor? Is it 110 or 220V ? Check various connections? Etc.?

Ron Williamson
06-10-2012, 05:49 PM
So far in my limited experience,23 years commercial/industrial professional machinery abuse,in 100% of cases when that kind of motor won't start,the points are corroded/eroded/arced.
It has never been the starting cap.
Actually,I lied.
There were the two bottom-of-of-the-barrel Chinese mag.starters on the 2hp dust collectors.
Quickly replaced with Made in Canada DPDT switches,they worked for years.
R

Paul Girouard
06-10-2012, 07:36 PM
So far in my limited experience,23 years commercial/industrial professional machinery abuse,in 100% of cases when that kind of motor won't start,the points are corroded/eroded/arced.
It has never been the starting cap.
Actually,I lied.
There were the two bottom-of-of-the-barrel Chinese mag.starters on the 2hp dust collectors.
Quickly replaced with Made in Canada DPDT switches,they worked for years.
R

So your contention is the switch is bad and it's damaging the caps? All three have leaked out the oil inside of them, so they all have been at least leaking oil , hence , bad. When I've replaced them.

Bill R
06-10-2012, 07:53 PM
The leaking oil is from them cooking. They overheat, and the seals crack causing them to leak.

Make sure you start switch and motor's centrifugal switch are good, and buy the expensive Chinese crap instead of the cheap crap.

Paul Girouard
06-10-2012, 08:08 PM
The leaking oil is from them cooking. They overheat, and the seals crack causing them to leak.

Make sure you start switch and motor's centrifugal switch are good, and buy the expensive Chinese crap instead of the cheap crap.


That's what I think I'm doing! By start swt. you mean the standard on / off swt. right? Not some other swt. hidden inside the motor case.

This has been a learning experience!

Tom Wilkinson
06-10-2012, 08:29 PM
i would guess it's the cetrifugal start switch contacts are burnt..

Peter Malcolm Jardine
06-10-2012, 08:57 PM
David G: Normal use I'd call it. I'm thinking it isn't Grizzly's issue , but a learning curve about what needs cleaned .

Peter : Have you blown out the motor? Is it 110 or 220V ? Check various connections? Etc.?

I will check everything.... haven't had a chance to take it apart yet, but I suspect it's dirt. It's a 110V

Bill R
06-10-2012, 09:17 PM
By start swt. you mean the standard on / off swt. right? Not some other swt. hidden inside the motor case.



Yes.

Paul Girouard
06-10-2012, 10:41 PM
Took the swt off , it moves freely , looks clean , spring action seems good.

http://i21.photobucket.com/albums/b299/PEG688/001-15.jpg



Contacts a bit pitted, maybe ,

http://i21.photobucket.com/albums/b299/PEG688/003-11.jpg


Cleaned with small-ish file , I would have used Donn's belt sander but he's a bit far away to run over and borrow it,

http://i21.photobucket.com/albums/b299/PEG688/005-7.jpg

I get a good spark on start up when the motor takes over and the switch changes, and a smaller spark on shut down as the switch reengages , I'd call it, for the next start cycle.

I may call Grizzly tomorrow to ask how much and when I could have a new centrifugal swt.

I still will want to see what the spark looks like with the new cap installed , which as I've said should arrive tomorrow via UPS.

Thanks again for the ideas / thoughts , etc.

Ron Williamson
06-11-2012, 05:02 AM
That should work for a good long time.
The innards on my dust collector motors look identical.
I'm GUESSING that the dirty points overload the cap. because it has power for too long,due to the fact that it takes a while to wind up and spin the points open.

R

Syed
06-11-2012, 07:54 AM
I would hesitate to install this capacitor on a 220 V motor and strongly feel that the capacitor specifications should be checked from the motor manufacturer before replacing the same thing again. 125 v AC is clearly underrated for a 220 v motor, it should be 250 w.v (working volts).


http://i21.photobucket.com/albums/b299/PEG688/10Juky2011.jpg

Paul Girouard
06-11-2012, 08:40 AM
Point taken , I think that is the original cap that failed back in July 2011, I'll ask about it as well when I call Grizzly today.

Steve McMahon
06-11-2012, 08:51 AM
Very good eye Syed. I missed that.
Ask for a 250V 600mfd Start Capacitor Paul.

Paul Pless
06-11-2012, 09:03 AM
250V 600mfd

What's mfd stand for?

hokiefan
06-11-2012, 09:08 AM
What's mfd stand for?

millifarads IIRC. The units for capacitance.

Cheers,

Bobby

Syed
06-11-2012, 09:14 AM
I think it would be micro farad.

pipefitter
06-11-2012, 11:50 AM
Personally, I would replace that switch after you get it running and take an amp reading on the motor both starting and running. The amp values should be on the ident plate. Those points appear to be almost through the cadmium layer. They will just pit faster from here on out. That looks like contamination damage from dust. You would expect to see a switch in that condition on something that starts and stops a lot more frequently than a table saw otherwise.

Either way, it looks like you have it figured out.

Paul Girouard
06-11-2012, 09:06 PM
Called Grizzly , that is the right cap for the motor.

I checked the price of a new swt. $5.75, the points , $3.75 , plus shipping and tax.


The new cap came , I installed it after removing the swt. and points to do the tap with the mallet while you blow out the motor , using the holes the wire go from the cap to the points thru. I did get a bit more dust out , not a lot more but a liitle.

I re-installed the swt , points , and new cap , she fires right off , a bit quicker than the old cap , the start up spark is a bit larger , and there is no spark on shut down.

I'm not a big beleiver in using a meter to test for amps or volts , as in the NAVAIR , you could read the right voltage on wires but when you added a load , a light bulb , valve , or what ever the power was going to power up some times IF you had a bad wire , corrosion , connector etc , the meter would read OK volts , but things still didn't work.


So I'm by passing Pipefitters advice on metering out the motor.

She's going back together , and back to work soon. If it breaks again I'll order new swt., cap, & points.

Thanks for the help! :ycool:

George Jung
06-13-2012, 07:37 AM
Great thread. In spite of myself, I even learned a bit! Good seeing you, Syed, btw.

Syed
06-14-2012, 11:48 AM
Thank you George, The feeling is mutual.

Paul Girouard
04-05-2013, 11:31 PM
Bump for BrianY

Canoeyawl
04-06-2013, 10:41 AM
A note about line voltage.
A few years ago I was noticing a few oddities with my machine tools. So eventually I tested the line voltage and found it was down, way down when I turned a few tools on. It turns out the line transformer on that circuit was originally set up for only 3 houses with old fashioned 30 amp services. A little 10 kVA transformer for all of us!
Now there are 5 houses with 100 amp sevices and almost everyone has electric stoves, waterheaters and etc. The original transformer was not up to it (it was installed in 1959 I think) A call to the utility company got it sorted and they changed the distribution transformer. All good now... The lights in the neighborhood don't dim down when I turn on the lathe.

john welsford
04-07-2013, 04:31 PM
One of my dayjobs is my little woodworking machinery servicing and setup business, and although I get my helper to do most of the electrical work I regularly replace switches and capacitors. We gave up using the originals, and now use Telemechanic switches which see to last much longer and dont suffer when full of dust.
The capacitors, dead right that they dont last long when the motors full of dust and crud or a bearing is getting a bit past it. Those motors are very easy to dismantle, three or four bolts and a couple of screws and the end comes right off and it all slides out.

John Welsford



Define significant spark.

You can see the orange flash in this photo , on the left side , that appears to be the contact point , the RH side does not appear to have a "point" unless it's been broken off. Should I see two flashes ? There is a flash , the camera can't catch it , to much delay and trigger slop or maybe it's the camera man , LOL , he's no damned good either!! LOL.

I think I should order a new switch to , just to be sure. What ya think??

http://i21.photobucket.com/albums/b299/PEG688/008-1.jpg

Paul Girouard
01-21-2016, 11:22 PM
Bump for Bruce Hooke.

Bruce Hooke
01-21-2016, 11:38 PM
Thanks Paul!