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  • mickeyf
    replied
    Remember that Watts is EI. Volts times Amps across the item consuming the power. The SCR/Triac is going to have extremely low voltage across it, as its resistance is very close to zero when conductiong. Its restance when not conducting is essentially infinite
    This is basically true (power consumption/waste heat/whatever = I*I*R). But while the device is transiting between essentially zero resistance and essentially infinite resistance it is in a linear, power dissipating mode. It is doing this 120 time per second. How long it takes to make the transition is also a factor.

    Even if this were the preferred means of control, without knowing the specs on the particular device you wouldn't want to push it.

    Leave a comment:


  • macona
    replied
    Originally posted by caveBob
    Thanks for the help Max, appreciate it. Pretty sure it came off a Nordic Track:



    Might just spend a little more for one in an enclosure with separate switches. Noticed that some include the ability to "brake", is this for stopping the motor quickly? If so, maybe a "SawStop" type capability might be within reach?...
    No, the only way sawstops stop so fast is they slam the blade into an aluminum shoe. We have one at Laika. The shop guys all chipped in to test it out. It does ruin the blade and the brake assy but a lot better than a lost finger.

    The other saws that have brakes have electromagnetic brakes.

    Leave a comment:


  • MaxHeadRoom
    replied
    Yes looks like Nordic Track, you need to take the flywheel off for better control.
    Max.

    Leave a comment:


  • caveBob
    replied
    Originally posted by MaxHeadRoom
    The term 'Treadmill' motor covers alot of different motors and manuf, from cheap uni-directional type (offset brushes) to quality type such as Baldor and Leeson and Nordic Track, one manuf even used a Universal motor with simple tach.
    Also be very suspicious of the stated HP of some of these motors, just looking at the frame size compared to the industrial equivalent shows that these motors might never sustain that kind of power for more than a few minutes without the possibility of over heating.
    The KB site has the manuals and specs for all their models, if you want to change direction either by simple SPST switch or by using a pot that swings through ±10vdc then the 4 quadrant type is what you would need.
    If you are in the US and want to use 120vac then using the KB/Baldor SCR type may limit your top end RPM with that motor, going with a PWM version will give you a slightly higher DC to get the top RPM.
    If you do not intend pushing that motor to the limit then the simple KBIC-125 should work for you.
    There is very little to hooking them up and the manual shows reversing etc.
    There is a nice 3rd party design on ebay right now for $40.00.
    Also when looking, Baldor sell the same KB drives relabeled.
    Max.
    Thanks for the help Max, appreciate it. Pretty sure it came off a Nordic Track:



    Might just spend a little more for one in an enclosure with separate switches. Noticed that some include the ability to "brake", is this for stopping the motor quickly? If so, maybe a "SawStop" type capability might be within reach?...

    Leave a comment:


  • MaxHeadRoom
    replied
    Originally posted by HSS
    Max, would that KB board on ebay replace the board in a bridgeport power feed? And if so how difficult would it be to connect with reversing without doing so at full voltage,

    Patrick
    See post #13 also in the KB-120 manuals there is info on reversing, the I1 & I2 inhibit terminals need to be closed when reversing, this allows the pot to remain at a set speed and when reversing takes place, releasing the inhibit allows the reverse to go through the accel curve.
    The enclosure models use a switch that can be obtained from KB or Baldor if needed, this is a special centre off reversing switch that does not allow the lever to move from one direction to the other, but causes a stop in the centre position at this point the inhibits are closed, releasing the switch momentarily allows the switch to continue to the other side.
    Max.

    Leave a comment:


  • HSS
    replied
    Max, would that KB board on ebay replace the board in a bridgeport power feed? And if so how difficult would it be to connect with reversing without doing so at full voltage, or better said, would I have to ramp the motor down before reversing direction? I don't know if I'm making sense with that last question.

    Patrick

    Leave a comment:


  • MaxHeadRoom
    replied
    300545535232
    Actually $30.00
    Max.
    Last edited by MaxHeadRoom; 03-27-2012, 03:08 PM.

    Leave a comment:


  • dian
    replied
    "3rd party design on ebay right now for $40.00."

    where is it?

    Leave a comment:


  • MaxHeadRoom
    replied
    Originally posted by caveBob
    PMDC Motor Model# N1CPM-144T
    P/N G-215392
    2.8 HP @ 130 VDC/2089 Watts
    1.75 HP Continuous Duty @ 100 VDC/1306 Watts
    The term 'Treadmill' motor covers alot of different motors and manuf, from cheap uni-directional type (offset brushes) to quality type such as Baldor and Leeson and Nordic Track, one manuf even used a Universal motor with simple tach.
    Also be very suspicious of the stated HP of some of these motors, just looking at the frame size compared to the industrial equivalent shows that these motors might never sustain that kind of power for more than a few minutes without the possibility of over heating.
    The KB site has the manuals and specs for all their models, if you want to change direction either by simple SPST switch or by using a pot that swings through ±10vdc then the 4 quadrant type is what you would need.
    If you are in the US and want to use 120vac then using the KB/Baldor SCR type may limit your top end RPM with that motor, going with a PWM version will give you a slightly higher DC to get the top RPM.
    If you do not intend pushing that motor to the limit then the simple KBIC-125 should work for you.
    There is very little to hooking them up and the manual shows reversing etc.
    There is a nice 3rd party design on ebay right now for $40.00.
    Also when looking, Baldor sell the same KB drives relabeled.
    Max.
    Last edited by MaxHeadRoom; 03-27-2012, 11:55 AM.

    Leave a comment:


  • J Tiers
    replied
    Reversing treadmill motors is doubtful.....

    yes they will *run* in reverse, but many have the brush setup made for one direction only, and will suffer from excessive wear and brush bounce, arcing, etc if reversed. I have one that squeaks loudly if turned in reverse even by hand.


    Originally posted by dian
    id rather continue running the motor from a variable transformer than spending something like 200 $ on a controller. well see how itl perform under load, but i tied braking the shaft manually and it seemed to be fine. i mean, i dont need to slow it down to something like 100 rpm. its a 6000 rpm motor.
    Where you are, prices are higher. Much higher.

    I have a couple of the "KB" controllers on things, and paid perhaps $20 for them... surplus.

    if you stay at high RPM you will probably get acceptable (even if not quite "Swiss precision") performance.

    Leave a comment:


  • dian
    replied
    id rather continue running the motor from a variable transformer than spending something like 200 $ on a controller. well see how itl perform under load, but i tied braking the shaft manually and it seemed to be fine. i mean, i dont need to slow it down to something like 100 rpm. its a 6000 rpm motor.

    Leave a comment:


  • macona
    replied
    Originally posted by HSS
    Macona, how do you reverse the motor using a KBIC board?

    Patrick
    There is also a reversion version that handles all the reversing for you, like:

    http://www.ebay.com/itm/KB-Electroni...#ht_500wt_1413

    http://www.ebay.com/itm/KB-DC-Motor-...#ht_600wt_1165

    http://www.ebay.com/itm/KB-Electroni...ht_1294wt_1165

    http://www.ebay.com/itm/KB-ELECTRONI...ht_1437wt_1398

    Leave a comment:


  • caveBob
    replied
    Originally posted by MaxHeadRoom
    That is just a simple triac or bridge and SCR controller, there is no accel/decel, current limit or other features.
    A better solution would be one of the KB or Baldor SCR or PWM drives off ebay.
    They can be had for as low as $20-$30.
    They will control DC as well as Universal motors.
    If that unit is just a triac, it would be limited to Universal motors.
    Max.
    How do you/would I know which one I need? Last summer I picked up a DC treadmill motor for the lathe but it had one of those multi-button controllers that the person I bought it from... lost. Is there a "Hooking Up a Treadmill Motor for Dummies" book or something like that available?

    Motor specs on the plate:

    PMDC Motor Model# N1CPM-144T
    P/N G-215392
    2.8 HP @ 130 VDC/2089 Watts
    1.75 HP Continuous Duty @ 100 VDC/1306 Watts

    OP, I don't mean to hijack your thread but I've been curious as to getting this little puppy running and thought/hope someone might know the answer.

    Leave a comment:


  • armedandsafe
    replied
    Originally posted by J Tiers
    Well, the millivolt idea is not correct at all.....

    The true voltage in the "on" state is often more like 1.5 to 2 volts, or around 2 watts per amp. That is why the heatsink is used.

    yes, it is a light dimmer circuit, basically. Used with a motor, it may or may not (usually not) produce a stable speed of the motor. In some cases, it may actually have an unstable mode where it will not correctly control speed, often at slower speeds.

    The "KB" type controllers are made to do a very good job, and they do.
    I hereby stand corrected. I was going on memory from when I was using them in the early 60s, just after they were introduced. I was using them with much higher voltages and frequencies.

    Pops

    Leave a comment:


  • J Tiers
    replied
    Originally posted by armedandsafe
    Remember that Watts is EI. Volts times Amps across the item consuming the power. The SCR/Triac is going to have extremely low voltage across it, as its resistance is very close to zero when conductiong. Its restance when not conducting is essentially infinite, so no current is flowing.

    So, 3800 Watts at 220 volts would be 17.27 amps. The voltage drop across the SCR/Triac would be in the range of a millivolt (or less,) resulting in 0.01727 Watts across the SCR/Triac.

    The device and circuit board should be able to withstand that.

    Pops
    Well, the millivolt idea is not correct at all.....

    The true voltage in the "on" state is often more like 1.5 to 2 volts, or around 2 watts per amp. That is why the heatsink is used.

    yes, it is a light dimmer circuit, basically. Used with a motor, it may or may not (usually not) produce a stable speed of the motor. In some cases, it may actually have an unstable mode where it will not correctly control speed, often at slower speeds.

    The "KB" type controllers are made to do a very good job, and they do.

    Leave a comment:

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