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Lathe doesn't spin at times.

Discussion in 'Woodturning Discussion Forum' started by Fadi Zeidan, Nov 9, 2016.

  1. Fadi Zeidan

    Fadi Zeidan

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    Hey guys,

    I have Delta 46-460, I only use on weekends for few hours so not heavily used. Last two weekends it started acting weird. I have small pieces of wood mounted, sometimes when turn the switch on and nothing happens as if it is off until I spin the piece of wood by hand, then it starts spinning fine. It doesn't do it all the time, but it does few times while turning.

    Anyone experienced something like that before?
     
  2. john lucas

    john lucas

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    Well I have on an older lathe that had a start capacitor on the motor. Don't know if the Delta has that or not. I'll go look in a few minutes since i have one of those lathes.
     
  3. Fadi Zeidan

    Fadi Zeidan

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    I called Delta, they said to take it to Northern Tools, they are authorized to service Delta machines. Northern Tools said "we could, but we are pretty green when it comes to Delta since we don't sell much of them but we can try". Takes 3-4 weeks to fix if I take it in. Delta guy said probably motor or cuircit inside the machine but he was not sure.
     
  4. Gerald Lawrence

    Gerald Lawrence

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    I am pretty sure that the Delta Midi I had had a start capacitor. When the start capacitor is bad the motor must be spun by hand to run, then the run capacitor kicks in . These capacitors are inexpensive . You can get one at an electric supply house. Be careful when you remove it as some do hold a charge.
     
  5. Fadi Zeidan

    Fadi Zeidan

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    No idea what it looks like or where it is on the lathe, I need to look it up :)
     
  6. Richard Coers

    Richard Coers

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    Start capacitor on an electronic variable speed motor? Can't imagine how that would work. It's either DC or 3 phase would be my guess. There was a big history of early hour switch and circuit board issues with that lathe. Also a history of dust getting in the switch. There were 2 generations of that machine if I recall correctly. Do some Google work, you should find someone else that had the same problem.
     
  7. olaf Vogel

    olaf Vogel

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    Is this single phase? (110 v or 220 v)?
    Sorry, I'm not familiar with it.

    So you flip the switch and presumably there is a humming sound?
    a - that means power is being applied to the motor, but its not spinning
    B - if there's no hum, then there's no power. Either your wiring is problematic, or the switch, or the motor.

    A motor start capacitor is a likely culprit, it looks like this
    [​IMG]
    and must be wired to the motor, but could be stuck anywhere close by.

    Or its stuck on the side of the motor like this
    [​IMG]

    Unscrew the cover, find the cap. There will be two leads connecting it. Take a pic of it.
    There will be numbers on the side, indicating the size of the cap. It can be ordered online.

    This is an easy fix for any local electric motor shop.
    If you want, you can order this online and replace it yourself.
     
    Last edited: Nov 9, 2016
  8. Bill Boehme

    Bill Boehme Administrator Staff Member

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    The Delta 46-460 is a variable speed lathe that uses a DC motor ... which means that it does NOT have a start capacitor although this would be somewhat similar a failing start capacitor in a single phase AC induction motor.

    This intermittent starting problem is a failure characteristic characteristic in brushed DC motors. There are several potential causes:
    • The best case scenario is that the brushes and commutator are "crudded up" and should be cleaned using contact cleaner. You will need to disassemble the motor to accomplish this.
    • Worn out brushes which are relatively inexpensive and easy to replace. You can unscrew the brush caps and pull out the brushes to check their condition.
      • If the brushes are badly worn, the commutator strips on the armature might be damaged to the point that the brushes and some commutator blocks are not making electrical contact. If the wear is bad enough a machine shop might be able to turn the commutators to clean up the damage.
    • The worst case scenario would be commutator sections on the armature going open circuit. Unfortunately, your description of the problem makes me think that this is the most likely failure. Another characteristic of this failure is that it will progressively get worse and the output power will also diminish as the problem worsens. When one commutator section opens up, it puts a heavier load on the remaining sections which eventually leads to an avalanche type failure. This last failure is typically the result of frequently overloading the motor to the point where it runs very hot or bogs down. However, it can happen from normal operation after many years of use.
    Before checking any of the above, look for some easy fixes like a loose connector on the electronics board, a bad speed control pot, or flaky switch that could be masquerading as a motor problem.

    The thought that Northern Tools is an Authorized Service facility for Delta doesn't give me a warm fuzzy. It sounds like they didn't give you a warm fuzzy either.
     
  9. Mike Brazeau

    Mike Brazeau

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    We have two of these in our guild and one of them we replaced the controller about three years ago with the Type Two controller. It behaves like this. If you just touch the handwheel it will start. Bill, they actually are some form of pulsed DC. One of our members repaired one that another member had that had died. Replaced an SCR and some other component. When evaluating the problem, we compared to mine, which works and a DC Voltmeter went crazy trying to measure the voltage to the motor. Would love to get a schematic for the controller. There is nothing warm and fuzzy about Delta these days!
     
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Is touching the handwheel to get it going an actual design feature or is it just an idiosyncrasy? :D ... or an idiosyncrasy that became a design feature? :D

    I am familiar with SCR's. I first built a motor speed controller using an SCR about 50 years ago when they were the latest new thing in semiconductor technology. The way that they work is to control the average DC voltage to the motor by chopping the output on and off when the input AC voltage reaches a certain threshold determined by the setting of the speed control pot. The fact that the DC output is pulsed isn't important, it's the average voltage which determines the unloaded speed of the motor.

    It's not surprising that your voltmeter went crazy. Digital voltmeters take instantaneous samples at regular intervals so the value could be anything from zero to several times the applied voltage. The reason that the reading could be greater than the applied voltage is that the motor is an inductive load and creates a superimposed AC resonance each time that the SCR switches, probably 120 times per second.

    I have used the Delta 46-460 several times in classes and also one that belonged to a friend and my impression is that the lathe was very nice ... quiet, smooth running, very well made mechanically. Not to say that there weren't issues that I didn't see.
     
  11. Fadi Zeidan

    Fadi Zeidan

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    I'm sure when I take it in to Harbor Freight, they will say they don't see anything wrong with it since it doesn't do it all the time and it won't do it said they will need 3-4 weeks if they can figure out what is wrong and to order parts.

    I'll use it for now until it gets worse, as long as it is under warranty then take it in.
     
  12. Richard Coers

    Richard Coers

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    And the guy at Harbor Freight is really going to be confused why you showed up there! LOL!
     
    Bill Boehme likes this.
  13. Leo Van Der Loo

    Leo Van Der Loo

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    That lathe has a history of switch problems, I would try first to blow out the controller box and switch, and then see if that helps some, on mine I have to make sure I push the switch down firmly, or else it might hesitate to turn on.

    Try keeping the dust off and out of the switch and reverse switch as much as possible, just blow it off, that has helped me so far, as I have that lathe 6 years already and I use this lathe quite a lot, still all original.
     
  14. Bill Boehme

    Bill Boehme Administrator Staff Member

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    They're not the only ones. The Powermatic remote start/stop switch is a cheapie that isn't environmentally sealed so getting wood dust in them is a problem.
     
  15. Tom Cadwalader

    Tom Cadwalader

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    When my Jet does this I put a vacuum hose over the start/stop switch and it's good for months at a time. I would start with the switch first.
     
  16. Fadi Zeidan

    Fadi Zeidan

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    I'll try that but if it is the switch, wouldn't it not run at all if you turn it by hand? Wouldn't that mean no power to the motor?
     
  17. Leonard Niemi

    Leonard Niemi

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    When I had this problem on my table saw, I took compressed air blew the motor out real good while still bolted in place. Problem solved.
     

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