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Thread: Lighthouse motors running hot

  1. #1
    Join Date
    Feb 2013
    Location
    Vicksburg MS
    Posts
    66

    Default Lighthouse motors running hot

    vacbox.jpg

    I just completed a vac box based on many of the designs created here with cooling intake, cooling exhaust, vacuum intake, and vacuum exhaust all separated into different compartments. I have (4) 230V LH motors, with 2 being my primary on one switch and another two being the backup, separated by a check valve, on another switch.

    The larger hole in the center of my box is for a supplemental fan to blow cool air cross the motors and exhaust the other end and out of my shop. I have my table set up in 4 zones, with a 1/2" muffler/filter serving as the vacuum intake cooling. With only one zone open and my primary motors on, I get about 6.5". It goes up to 8" with all 4 on.

    The problem is that the motor temps go beyond 160 degrees withing 2 minutes of running. I have a thermostat mounted on the aluminum housing on one of the motors, but it only goes up to 158 degrees, so I just shut it down. I've seen where many guys report operating in the 120-130 range, and I don't understand what I am doing so differently. The temp in my shop the last few days has been 85-90, so I'm sure that doesn't help.

    I have them wired to a single 30A breaker through double pole switches. Other than that, nothing special. I do notice that a small spark shoots out all of the motors about one every 3 or 4 starts. That's a bit concerning and doesn't seem normal. Could I have something wired wrong?

    There isn't much of a difference in my version than many of the others posted here. In fact, I added the extra cooling as a backup and to mainly keep the extra hot air out of my hot shop. Any tips and suggestions are much appreciated.

  2. #2
    Join Date
    Nov 2006
    Location
    LaGrange GA
    Posts
    590

    Default

    I built the 4 motor vac box with two motors the beginning of this year. I plugged two of the ports so I could add the last two later on. My motor temps are hitting 145 degrees under hours of continued use. I most of the time use two of my zones and pull 7 on system start, and just this week it dropped to 6 at the lowest while cutting out 62 - 8"x8" acrylic blanks out of two full sheets.

    I am brand new to large scale vac hold down, but don't give up. The part of my shop the bot is in has no temp control so it is smoking hot back there right now. I have my bleeder valve open just enough to were I think the motor are getting enough air, but the vac gauge still looks good.

    by the end of this year I plan on adding two more lighthouse motors. Then I think I can run the whole 4x8 and hold just like I do with half the table. But, remember it's all about how you use the vac and what you are cutting. Every job you put on the table is different.

    Dave

  3. #3
    Join Date
    Apr 2011
    Location
    New Jersey
    Posts
    120

    Default

    Any restriction or inefficiency in the system is going to increase heat. Running the exhaust across your shop may very well be the main issue. You may be heat-soaking the motors because of poor ventilation. Also any restriction/filtration on the intake will also cause the motors to work harder. If your box has leaks, again, your pumps are going to have to work harder which has to result in increased temps. Also make sure all the PVC, the vacuum grid, and spoil-board are all sealed up properly. I'd "fix" any issues you may have and then simplify the system as much as possible. You need a baseline, and then you can start trouble shooting.

    Also you have to remember, it's hard to say how people are measuring temps. The way person X measures the temp may be very different than you have. That makes the comparison not exactly valid.

  4. #4
    Join Date
    Feb 2013
    Location
    Vicksburg MS
    Posts
    66

    Default

    My table is set up in 4 zones (each zone being 2'x4'). With 2 zones open and 2 motors running, the temp tops out at about 145 degrees. Using only one zone and/or turning on the additional 2 motors runs the temp beyond 158. The good news is that I can get my vacuum up to 9", so I don't think I have a leak in my system.

    My intake filter is that cheap green cut-it-yourself return air filter and should not be restrictive. My shop is really hot and I'm sure that isn't helping. I've tried different thing like using a more powerful fan for the cooling exhaust, not using a fan, and blocking off the additional cooling hole, and opening the 1/2" bleeder valve wide open.

    One thing I did notice is that my 230v motors are getting more like 245v, but that shouldn't have that much of an effect, right?

  5. #5
    Join Date
    Feb 2013
    Location
    Vicksburg MS
    Posts
    66

    Default

    Ross,

    I've thought about how all the air gets moved and if I'm creating some sort of circular effect with the air instead of using fresh air - like I may be pushing the heated air from the vacuum exhaust across the motors.

    How everyone is measuring their temp is something I have been wondering about. I'm pretty sure how I have mine mounted (in the motor housing) probably gives the highest temps in the system, and that was how I wanted to monitor it. Like you say, I just don't know if I am comparing apples to apples when seeing what others report in their systems. The air coming out of the exhaust sure doesn't feel 150 degrees, but that's not scientific.

  6. #6
    Join Date
    Dec 2008
    Location
    , Richmond Tx
    Posts
    1,029

    Default

    Did you add the bleeder orfice so they still have a little air flow through them even when all valves are closed? Mine have been working for about 4 years and I have no idea how hot they are. I do remember the bleeder being critical to not overheating them though.
    Kenneth

  7. #7
    Join Date
    Feb 2013
    Location
    Vicksburg MS
    Posts
    66

    Default

    Yes, I have a bleeder valve with a 1/2" muffler/filter.

  8. #8
    Join Date
    Feb 2013
    Location
    Vicksburg MS
    Posts
    66

    Default

    IMG_1795.JPGIMG_1796.jpg

    The white wire is my thermostat sensor. I glued it in the hole on the housing at about the 4 o'clock position.

  9. #9
    Join Date
    Dec 2008
    Location
    , Richmond Tx
    Posts
    1,029

    Default

    I think you are pulling heat from the motors back into the cooling fins to some degree. I have flexible drier duct on each of my motors drawing in outside air to the cooling fan of each motor. I know you have a fan blowing across them but I would be curious what the temp is running on the intake to the colling fan of each motor. Basically mine would be like there are 4 holes out of the top of the removable lid in your pictures and duct work goes from the end of each motor out to that hole. They draw in clean cool air this way instead of heated air. Also those vents come from the bottom of my enclosure to keep them cleaner. I'm not saying my set up is better, but it has a lot of years on it.
    Kenneth

  10. #10
    Join Date
    Sep 2013
    Location
    Bluffton SC
    Posts
    65

    Default

    I wont put pictures of mine box it too ugly but it usually runs about 110F after few hours of cutting. I did cut round holes in the box were fans are going out so they suck cold air from outside of the box.

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