Capacitor Start Motor Stopping

Discussion in 'General Electronics Chat' started by tigerfish0102, Jan 2, 2010.

  1. tigerfish0102

    Thread Starter New Member

    Oct 17, 2009
    9
    0
    Hi Guys,
    Can you help me guys, i have a project to stop a capacitor start motor using as grinder. Because our grinder start easily but it stop for about 10mins. I would like to make it stop as quickly as possible.
    thanks guys,
    tigerfish
     
  2. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
  3. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    May I introduce you to the current spate of "Safer" circular saws, and similar consumer power tools, that are equipped with a "brake" circuit ?? Quite impressive. They work quite well.............for a while.:rolleyes:

    Until such time as powertool mfgrs. learn to build some beef into this circuitry, it will remain useless.

    Beef ? Stop making armature bearing and brush housings out of any type of plastic for starters, yet that is a rant for another day.:D

    Not much to do for a brake on your grinder, aside from keeping a block of hardwood on a chain to stop it before you walk away. :p:p

    { why do I feel I'm gonna catch grief for this one }
     
    Last edited: Feb 10, 2010
  4. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    instead of griping about what isn't, how about helping with what might?
    and forget about the block of wood thing.

    but I must say, I had a Skilsaw bearcat that erupted when the brake came on. It could have been ugly!

    there is a qualitative difference between hand held saw brakes and industrial motor brakes.
     
    Last edited: Jan 2, 2010
  5. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    OK.....I agree ,the block of wood thing was a wee bit sarcastic, but watch this..........

    I have been in the industrial fields for nigh on 50 years, and have witnessed the decline in quality of more products than I care to mention.

    My ire, is directly connected to this shift in recent years, of seemingly everything the United States of America excelled in, to the likes of China.
     
    Last edited: Apr 23, 2011
  6. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    I will not disagree with you because I cannot disagree.

    the link I included for tigerfish was from a quality American company.
    http://www.idicb.com/index.html
    the manufacturer I represent uses some of their product in various applications and with excellent service and no warranty issues.

    I have a Milwaukee 14 inch metal chop saw that was built way back when, its a tank but still purrs, cuts through 1" steel like butter. a friend loved it so much, went and bought a new one, what a disappointing embarrassment!

    I feel the pain.
     
  7. tigerfish0102

    Thread Starter New Member

    Oct 17, 2009
    9
    0
    Hi Guys,
    The brake you are referring to is not suitable for the bench grinder. Is the another way for this kind of grinder.
    tigerfish
     
  8. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    It depends on how involved you want to get with it.
    We can more than likely wire a momentary rotation reversal circuit in it. This would provide a type of dynamic braking situation. But there are more factors involved and taken into consideration here than just adding a switch and a few wires.

    a method an old (cantankerous but revered) blacksmith used on his HUGE bench grinder was he installed a v-belt pulley on the side of one of the grinding wheels. He ran a belt from the pulley down to another shaft that had a type of parking brake on it. After he shut the grinder down he would pull the lever and bind the driven shaft and stop the wheel. Like I said, it was a HUGE wheel and if it wasn't stopped with the brake, it would spin forever (not literally).

    What is the manufacturers brand/model of bench grinder. The volts, amps, watts, horsepower or any other info you can provide. Also, what is the width and diameter of the grinding wheel(s).
     
    Last edited: Jan 8, 2010
  9. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    One method of stopping a squirrel cage motor is to apply a low voltage DC to the windings. Would require a relay setup to completely isolate the DC supply from the motor when not in the braking mode as well as to totally isolate the motor from the AC source while using the brake. Momentary push button to activate. Hold button until wheel stops, release.
     
  10. tigerfish0102

    Thread Starter New Member

    Oct 17, 2009
    9
    0
    hi guys,
    thanks for your ideas..
    thanks,
    tigerfish
     
  11. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    I had time to waste, a bit of curiosity to satisfy, a 1 horsepower motor with a 12 inch buffing pad that freewheeled about a minute after shutting off, and salvaged components to waste, so here is what transpired.

    components salvaged from various stuff used:
    2200uf 400v aluminum electrolytic from a marquee sign board,
    50Kohm 5watt sandstone resistor from same sign board,
    1 blade-2 way knifeblade switch from Perdue University Physical Plant,
    72HF60 70 amp rectifier diode from battery charger.

    These are components I had available and not derived from calculations other than overkill for safety sake.
    There are those here that may donate time and formula to achieve this for a specific application and those that will profess that it will not work.

    I operated this set-up dozens of times with desired outcome and no apparent overheating of motor or components. The motor will stop in about 4 to 10 seconds (i edited this a couple times. it is not always the same amount of time but will stop within the 4 to 10 second range) as opposed to the 50 to 60 seconds it normally took.

    I do not know the RPM or horsepower of your motor, or the weight, diameter of your grinding wheel(s) but I am certain that it will generate a heluva lot more inertia than my buffing wheel! Will it work in your application? Have a fire extinguisher handy!

    The motor I experimented with was a 1 horsepower motor, 115volt,
    Dayton 6K562 Motor. 1725 RPM, 10amps full load (5 amps at 230 volts). 60 hz and capacitor-start.




    attached is the simple AC motor brake circuit I have been wanting to try since this thread started.
     
    Last edited: Jan 23, 2010
Loading...