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Thread: Grizzly Gunsmith Lathe Break

  1. #1
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    Grizzly Gunsmith Lathe Break

    Can someone tell me what sort of mechanism Grizzly uses as a spindle break on thier lathes?

    Thanks,

    Pete

  2. #2
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    My Grizzly (G9731) has a hyd disc brake mounted on the motor shaft.

    Richard

  3. #3
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    Thanks Richard

    Quote Originally Posted by Richard View Post
    My Grizzly (G9731) has a hyd disc brake mounted on the motor shaft.

    Richard
    Appreciate it!

    Pete

  4. #4
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    Might could set up brake with a VFD. I have my motor set to stop quick. Such thing as braking resistors for them.

  5. #5
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    I saw somehing about that

    on a Youtube. The only thing I miss from my Heavy 10 is the feed clutch. Sure would be nice to have a way to stop quickly.

    Pete

  6. #6
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    Pete,
    I hooked a braking resistor up on my vfd, and it works great. Cost about $40 or less and was very easy to hook up...and I am not an electronic wizard. It will stop my chuck at low speed in under .5 second. At high speed (2000rpm) about 2 seconds or it will override the system, and it will freewheel though still at a much reduced speed. I bought my brake resistor on ebay, and it was significantly less expensive than through automation direct or wolf automation, etc...

  7. #7
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    Thanx

    Quote Originally Posted by savet06 View Post
    Pete,
    I hooked a braking resistor up on my vfd, and it works great. Cost about $40 or less and was very easy to hook up...and I am not an electronic wizard. It will stop my chuck at low speed in under .5 second. At high speed (2000rpm) about 2 seconds or it will override the system, and it will freewheel though still at a much reduced speed. I bought my brake resistor on ebay, and it was significantly less expensive than through automation direct or wolf automation, etc...
    Sounds like something to try.

    Thanks.

    Happy New Year,

    Pete

  8. #8
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    Swap in a 3-phase motor and use the VFD for instant brake.

  9. #9
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    Quote Originally Posted by brickeyee View Post
    Swap in a 3-phase motor and use the VFD for instant brake.
    Keeping in mind that you need to consider duty cycle when using braking resistors especially if you desire an almost instant stop.
    And not all VFD’s have the feature, especially some budget versions.

  10. #10
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    Ive noticed

    some of the new machines being offered come with a 3 phase option with a built in VFD. Hobby machining appears to be growing a bunch. I can see that the prices of used machines has gone up a lot over the past few years.

    Pete

  11. #11
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    Quote Originally Posted by Michael Huebner View Post
    Keeping in mind that you need to consider duty cycle when using braking resistors especially if you desire an almost instant stop.
    And not all VFD’s have the feature, especially some budget versions.
    For the most part the VFD must be oversize (by a rather large amount) to withstand the huge currents and voltage steps that occur.

    Solid state semiconductors are extremely vulnerable to excessive current and voltage.

    This is not a 'duty cycle' heating type issue, but an instantaneous excessive voltage or current through the semiconductor junctions.

    The actual breakdown value of almost all semiconductor junctions is pretty variable based on intrinsic defects in the junction.

    The method generally is to grossly derate absolute peak currents and voltage by very large factors (sometimes many hundreds).

    A very few volts over on a part rated many hundreds of volts is often all it takes to totally destroy the junction.
    So instantly that there is no practical way to protect the part from destruction.

    We used to have some rather spectacular explosions of high voltage transistors in 'hockey puck' glass/ceramic hermetic packages.

  12. #12
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    Of Wet Blankets:

    Quote Originally Posted by brickeyee View Post
    For the most part the VFD must be oversize (by a rather large amount) to withstand the huge currents and voltage steps that occur.

    Solid state semiconductors are extremely vulnerable to excessive current and voltage.

    This is not a 'duty cycle' heating type issue, but an instantaneous excessive voltage or current through the semiconductor junctions.

    The actual breakdown value of almost all semiconductor junctions is pretty variable based on intrinsic defects in the junction.

    The method generally is to grossly derate absolute peak currents and voltage by very large factors (sometimes many hundreds).

    A very few volts over on a part rated many hundreds of volts is often all it takes to totally destroy the junction.
    So instantly that there is no practical way to protect the part from destruction.

    We used to have some rather spectacular explosions of high voltage transistors in 'hockey puck' glass/ceramic hermetic packages.
    Please don't confuse with us wiith hard facts! it's way to hard to deal with! .

    Pete

  13. #13
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    Quote Originally Posted by brickeyee View Post
    For the most part the VFD must be oversize (by a rather large amount) to withstand the huge currents and voltage steps that occur.

    Solid state semiconductors are extremely vulnerable to excessive current and voltage.

    This is not a 'duty cycle' heating type issue, but an instantaneous excessive voltage or current through the semiconductor junctions.

    The actual breakdown value of almost all semiconductor junctions is pretty variable based on intrinsic defects in the junction.

    The method generally is to grossly derate absolute peak currents and voltage by very large factors (sometimes many hundreds).

    A very few volts over on a part rated many hundreds of volts is often all it takes to totally destroy the junction.
    So instantly that there is no practical way to protect the part from destruction.

    We used to have some rather spectacular explosions of high voltage transistors in 'hockey puck' glass/ceramic hermetic packages.
    The ‘duty cycle’ I refer has nothing to do with the semiconductors, it is the braking resistor. You can over rate the power of the resistor but the cost would outweigh the benefit for hobby type installations.
    IMHO it is best to program the VFD to as close as instant stop as you can get for E/Stop only and program a small time to ‘free run’ to stop for normally stop function.

    I also install a OMRON Safety relay which stops the VFD transistors commutating and then cuts all power, when E/stop is pressed.

    This is what I do, but those who install them on there machines can decide how safe they want there installation to be.

  14. #14
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    With respect to the need for an overly large VFD for a particular motor this isn't true for the units I purchased. I spoke with the manufacturers directly because I read this on various sites and it seemed counter to the websites advertising the drives. I have an automation direct drive on my mill and an Hitachi on my lathe. Both drives are matched to the motor HP within 1/2hp. According to the manufacturer there is no need, anymore, to oversize your drive. The hobby machines we are running just don't pull that much amperage, and as long as the unit you are buying covers the max amps of your motor (i.e my 2.2kw 3phase motor has a 10 amp max draw which calculates out to my hitachi drive drawing something on the order of 25 amps +/- at the breaker.) I doubt I will ever approach that level of draw and have programmed my VFD to ramp slowly over 5 seconds to avoid just that situation.
    I am not the end all when it comes to the rest of the electronics, but I did talk to the source when it comes to this particular subject. Two separate companies.

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