What's happening in your shed?

Tom Snape

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It kicks out after running about 10 minutes, even if the motor is unloaded (blade completely off the wheel). This only started happening last week.

It's a 1.5 hp 1 ph 220 motor, Italian made. There is no start capacitor. There is a 60uf run capacitor. I had the capacitor tested, and it tested 60.5 uf. The motor always ran hot; there is a warning label on the motor stating max. temp is 70 deg C. I attached a thermocouple to the ground lug on the motor case and it read 56 deg C when the motor tripped, but after that rose to 76 deg C. So I do think the motor is getting hot inside, and the temperature switch is opening.

The start/stop switch on this thing is another European part (I got a quote of $198 to replace it). It has a coil that holds the contacts closed and the temperature switch in the motor is in series with the coil, so when the temperature switch opens, the start/stop switch coil is de-energized and the contacts open. A Laguna rep suggested the switch is bad, but I don't think that's the problem, because I can always run about 10 mins and then it trips. My test with the thermocouple tells me the motor is going over temperature. I think the temperature switch is doing it's job.

So back to the motor; either the motor is going bad, or the run capacitor isn't working right and messing up the phase of the second winding, which could also make the motor run hotter. Even though it tested out okay on a multimeter, I ordered a new $20 capacitor to try first because if that's not it I think I'm looking at a big bill (or a new saw?)

The motor mount is a 80C face, which I never heard of and can't find from US distributors. I could have a new mount made for a 56C motor. If I went with that, I'd probably also have to have the drive pulley modified to match the motor shaft. Also, Laguna rep told me they sell upgrade kits using US spec motors, but I'm sure it's pricey.
 
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dwizum

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Got an infrared thermometer or camera so you can take a look at where and when it's heating up? Also to help validate it's not the switch. 80c is definitely an unusual frame size. Capacitor sounds like a good next step. Did you check the windings out with your multimeter?
 

printer2

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Yeah, bearings. Need to rebuild my bandsaw. Do you have access to a ampmeter. You really need to know what the motor is drawing. Seems you have a good understanding on how to troubleshoot it. If I was at work (had enough of that though) I would megger between the windings and the frame. Probably disconnect the capacitor before that. Most people do not have a megger but you can try an ohm meter from the windings to ground. You should also be able to test the winding resistance for the run winding and the start winding (or as it sounds, it is a continuous winding). I never thought about it when I was doing it until I talked to one of the guys on how I troubleshoot. If nothing obvious I figure out what I think is working and put that aside and try to figure out why the rest would not.
 

Tom Snape

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Yeah, bearings. Need to rebuild my bandsaw. Do you have access to a ampmeter. You really need to know what the motor is drawing. Seems you have a good understanding on how to troubleshoot it. If I was at work (had enough of that though) I would megger between the windings and the frame. Probably disconnect the capacitor before that. Most people do not have a megger but you can try an ohm meter from the windings to ground. You should also be able to test the winding resistance for the run winding and the start winding (or as it sounds, it is a continuous winding). I never thought about it when I was doing it until I talked to one of the guys on how I troubleshoot. If nothing obvious I figure out what I think is working and put that aside and try to figure out why the rest would not.

I borrowed a Fluke 1507 meter and megged the motor. I got about 500 M ohms between the windings, and about 2000 M ohms between each of the windings and ground. I think these are good numbers. Bearings seem smooth on all parts. I'm sure hoping the new capacitor makes a difference.
 

Timbuck

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Yeah, bearings. Need to rebuild my bandsaw. Do you have access to a ampmeter. You really need to know what the motor is drawing. Seems you have a good understanding on how to troubleshoot it. If I was at work (had enough of that though) I would megger between the windings and the frame. Probably disconnect the capacitor before that. Most people do not have a megger but you can try an ohm meter from the windings to ground. You should also be able to test the winding resistance for the run winding and the start winding (or as it sounds, it is a continuous winding). I never thought about it when I was doing it until I talked to one of the guys on how I troubleshoot. If nothing obvious I figure out what I think is working and put that aside and try to figure out why the rest would not.
It’s a bandsaw ..that fine dust gets into everything....stop start switches...safety switches on doors ..bearings get full of dust ,in the band wheels even the doubled shielded type..check all these first .. the clogged motor bearings will generate heat and cause the motor cut out circuit to switch off...if all this fails then get a new motor. :)
 

dwizum

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Yes - bearings can feel smooth as butter and run for years with dust in them but they'll get hot! I'd like to hope that Laguna spec'd parts with good dust seals but you never know after 17 years. This is where an IR gun or camera can come in handy since you can see which parts of the motor heat up over that 10 minute period. It's helpful to have a "known good" image of the motor to compare to, but even without, it's pretty obvious when a bad bearing is heating things up.
 

Timbuck

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Yes - bearings can feel smooth as butter and run for years with dust in them but they'll get hot! I'd like to hope that Laguna spec'd parts with good dust seals but you never know after 17 years. This is where an IR gun or camera can come in handy since you can see which parts of the motor heat up over that 10 minute period. It's helpful to have a "known good" image of the motor to compare to, but even without, it's pretty obvious when a bad bearing is heating things up.
Switches can heat up as well and cause problems if the contacts get dust in them....When my bandsaw’s have stopped working (I have had about 6 up to now) it was always down to dust in the electrics causing the problem.
 

Tom Snape

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All good suggestions. I've opened the switch box and it's spotless inside. As I mentioned before, the Laguna rep suggested the switch, but based on the temperature readings I'm seeing I tend to think the motor is overheating. I just ran another test with the motor completely free (removed belt from bottom pulley). The motor spins over freely. I can give it a quick spin by hand and it keeps going 20 seconds or more. I ran it this way, and it kicked out after 11 mins, with thermocouple reading about 54 deg C. After stopping, the temperature rose to over 74 deg C. I also checked to voltage to each coil at the motor while it was running and it was steady 123 V. I thought the new capacitor would be here today but it's a no show so far.
 

Titchtheclown

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A minor landmark. I just used the last of my roll of 80 lb nylon fishing line. Most of my ukes have been strung up using line from this roll. Good thing I bought a new roll already.20200826_105856.jpg
 

printer2

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I really need to finish my 2x4 challenge uke. :wallbash:

I couldn't remember If I was in it or not. Had to look back, seems I had some trouble. I may have to build one yet. Can't remember, does the fretbord have to be from the 2x4?
 

dwizum

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Fretboards, bridges, and neck blanks oh my!

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And a stack of backs and sides...

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Walnut, rosewood, and myrtle. The myrtle has some really pretty tight flame figure, I have been hesitating to use it because I was afraid of bending it. But I just did a test piece from a scrap and that stuff bent like a sheet of rubber, it went great! It bent easier than just about anything I can remember and didn't crack unless I really forced it. very excited now to get some put together...
 

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Jerryc41

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My tennis racket uke is sitting patiently, waiting for me to get back to it.
 

printer2

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There were significant variations to the 2*4 theme but I for one baked my fretboard from the 2*4. Others did not.
We also lacked an official referee and those of us living in metric land used 90 by 45 which approximate s 2*4 dar.

Just have fun with it was the main idea.

https://forum.ukuleleunderground.com/showthread.php?114726-2x4-challenge/page40&highlight=challenge

I see I started with it but dropped it because of problems. I did a 2x4 guitar though, still have to finish the frets, bridge and tuners.