Page 2 of 2 FirstFirst 12
Results 16 to 24 of 24
  1. #16
    themage21 is offline So that's how you change this field...
    Join Date
    Aug 2012
    Location
    Emu Plains, NSW
    Age
    35
    Posts
    133

    Default

    Shedhand,

    The thermal protection is the main thing you need for protecting your motor. A 3 phase CB in an enclosure can do that job no worries, although $92 for a start/stop box is pretty competitive when you factor in what your own time is worth.

    With rotary switches, well, depending on which one you used, it may not be rated for motor start (and particularly) stop function. Electric motors chuck out a high voltage spike when the current to them is suddenly interrupted, which if the contacts on the switch are not designed with consideration for, leads to premature death of the switch. It's less a safety thing and more a "it'll probably break sooner than you'd like" sort of thing. The DOL box in the link above has a contactor (big a*** relay), which snaps open far faster than a rotary switch will, which minimises damage from on/off cycles. For most larger equipment, it's far preferable to having switches which directly control on/off. It also normally deactivates on loss of mains, which is another important safety feature. Also, once you've got a control box, it's normally trivial to add emergency stop buttons on more convenient locations on the saw.

    In the mean time, you should be right to use the saw, but the idea will be that you need to listen to your machine. If it bogs down, pull the work back and give it a break at no load speed before pushing on. If it stalls, stop pushing and/or power immediately. All the commonsense stuff that comes with being the owner of a machine that you plan on being the owner for for a long time.

    It also helps your motor if you periodically remove it from the machine and clean it out. Being choked by sawdust is probably a bigger cause of death of woodworking machinery motors than anything else and the most easily avoidable.

    You're probably already aware of all of this (to some degree or another), but I'd say it's pointless not using your machine for the sake of a switch. Change your habits to match the design of the machine - it'll make sure that it lasts longer even after you upgrade it later on.

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Age
    2010
    Posts
    Many





     
  3. #17
    Join Date
    Dec 2011
    Location
    SC, USA
    Posts
    439

    Default

    It is worth googling up your motor and see if they recommend a separate motor starter. Some small motors dont need one.

    chances are - if it starts and runs cool as-is, you are probably Ok. The danger would be if the motor hums and makes all sorts of commotion on startup or runs hot while running.

    Switching from a 2hp single phase to 4hp 3 phase most likely resulted in a motor that hardly runs under any load even when sawing.

    Now - if its running hot - I would check to make sure your bearings are good, guides are set right, and nothing is binding.

  4. #18
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    23,131

    Default

    Quote Originally Posted by truckjohn View Post
    It is worth googling up your motor and see if they recommend a separate motor starter. Some small motors dont need one.
    I have never seen a 4HP or even a 3HP and most 2HP 3 Phase motors without a starter.[/QUOTE]

    Were not taking peanut currents here.
    4HP at about 80% efficiency is around 9+A at 415V. If the blade jams this may cook a motor faster than you can switch it off, given it usually takes an operator a couple of seconds to work out what is going on. My guess is the OPs setup has one belt so hopefully the belt will slip.

    Switching from a 2hp single phase to 4hp 3 phase most likely resulted in a motor that hardly runs under any load even when sawing.
    Were also not talking about cutting hot butter north american timber here, but stuff that is up there along with some of the harder woods on the planet. These timbers will load up a Table saw very quickly and use every bit of the 4HP. This is almost certainly why the OP was having problems in the first place.

    Just to give you an indication my 3HP saw pulls around 12A at 240V to rip aussie hardwood and it is very easy just to push a bit harder and hit 15A. The thermal cut out kicks within seconds if it reaches 17A. At that point that so called 3HP motor is outputting 4.4HP

  5. #19
    Join Date
    Feb 2003
    Location
    used to live in Sydney, now it's Canada
    Age
    64
    Posts
    10,719

    Default

    Just to give some perspective for truckjohn
    Quote Originally Posted by BobL View Post
    Were not taking peanut currents here.

    Just to give you an indication my 3HP saw pulls around 12A at 240V to rip aussie hardwood and it is very easy just to push a bit harder and hit 15A. The thermal cut out kicks within seconds if it reaches 17A. At that point that so called 3HP motor is outputting 4.4HP
    if this were a single phase US saw, the currents quoted by BobL would be about 24A and 30A on a 120V supply.
    regards from Canada

    ian

  6. #20
    Join Date
    Nov 2005
    Location
    Gippsland, Vic
    Age
    67
    Posts
    4,340

    Default some pics of the converted saw.

    IMG_1003.jpg
    Saw Model
    IMG_1002.jpg

    wiring from switch to motor
    IMG_1001.jpg
    switch type
    IMG_0998.jpg
    motor specs
    IMG_0997.jpg
    the motor.

    Unlike the original 2hp single phase, this motor essentially starts at max revs whereas the old one started slow and built up to speed.
    The ASEA motor is very quiet running compared to the old one. its mounted on a hinged plate with the weight of the motor provided the tension to the belt drive. there is only a single belt pulley on the arbor.
    Comments welcomed.
    cheers
    Mike
    Attached Images Attached Images
    If you never made a mistake, you never made anything!


  7. #21
    Join Date
    Apr 2014
    Location
    Little River
    Age
    73
    Posts
    826

    Default

    With that single belt drive I think that you will have difficulty transmitting the full power of the motor without slipping so if there is a jam rather than the motor burning out immediately you will get a lot of smoke and will need to replace the belt as the burn will leave a bit of the belt narrower and this will cause a lot of vibration in the machine.

  8. #22
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    23,131

    Default

    Thanks for posting the pics

    The most obvious thing I can see is that's not a 4HP motor, that is a 4kW motor! so 5.4HP - even more of a reason to have a proper starter on it.

    I agree with Bohdan that the motor won't transmit the power efficiently with one belt.
    It also looks like the wrong size belt for the motor pulley, the belt is sitting too far down into the pulley, if the bottom of the belt touches the bottom of the pulley the belt will definitely slip and burn up

    I'm not sure about whether put such a big motor on a lightly built machine is a good idea given the 2HP carbatec machine is not exactly a HD machine.
    I figure a 50% to 100% increase in most motors should be OK but 5.4HP represents a 170% increase.
    Probably OK for occasional use but I doubt the trunion is going to last long term given the amount of torque that motor can generate.
    In that case leaving it at 1 belt is probably one way to save it although you should get the right size belt / pulley.

  9. #23
    Join Date
    Apr 2014
    Location
    Little River
    Age
    73
    Posts
    826

    Default

    Quote Originally Posted by BobL View Post
    Thanks for posting the pics

    In that case leaving it at 1 belt is probably one way to save it although you should get the right size belt / pulley.
    Your right Bob I think that it is an A belt on a B pulley so the belt will have a real short life.

    The A belt pulley groove is 13 mm wide at the top and the B is 17 mm. (or in the old numbers 1/2" and 5/8")

    The correct change would need replacing of the pulley in the saw if it is, as I suspect, an A pulley, however you would probably get away with running a B belt on an A pulley unless it slips too much then you need to change the arbour pulley.

    I suspect that the pulley on the motor is original and shows that the motor requires two B belts to transmit all of its power so if you were to change the arbour pulley you need to get a double. That however could result in a real monster of a saw.

  10. #24
    Join Date
    Nov 2005
    Location
    Gippsland, Vic
    Age
    67
    Posts
    4,340

    Default

    A monster??😲i just took the pulleys off the big motor because they werent closed up properly due to rust and gunk. Cleaned up nicely and the existing belt is no longer so deep. But will get a new reinforced belt. And a replacement pulley for the saw arbor if its too narrow for the new belt. I have about 20kg of sheet lead which ill put under the saw where the frame crossmembers are so the saw doesnt leap about when i start it. Have also contacted my friendly sparky for a second hand switch to suit. My dusty is 5 hp so a start switch like its would be ok I'm assuming. I'm enjoying this exercise - even if it ends up on the scrap yard pile. Will pissibly sell my Gibson Les Paul to buy a new saw. 😉
    If you never made a mistake, you never made anything!


Page 2 of 2 FirstFirst 12

Similar Threads

  1. 3 Phase question
    By Cam.H in forum WOODWORK - GENERAL
    Replies: 11
    Last Post: 11th Oct 2013, 09:05 AM
  2. Electricity supply question - 3 phase vs 1 phase
    By Avery in forum NOTHING AT ALL TO DO WITH WOODWORK
    Replies: 18
    Last Post: 24th Jul 2013, 11:01 AM
  3. 3 phase motor question
    By Com_VC in forum METALWORK FORUM
    Replies: 17
    Last Post: 10th Oct 2012, 12:29 AM
  4. Another VFD & 3 phase question
    By simonl in forum METALWORK FORUM
    Replies: 74
    Last Post: 6th Oct 2012, 07:41 PM
  5. 3 Phase Question
    By mdfdust in forum PLUMBING, ELECTRICAL, HEATING, COOLING, etc
    Replies: 3
    Last Post: 5th May 2007, 11:13 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •