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Thread: Powermatic 90 needs more powa

  1. #1

    Powermatic 90 needs more powa

    So I picked up and got a 90 running with a VFD and the original 1hp motor, used it for almost a year, and so far only 2 complaints:

    Low torque - When I'm turning big bowls, anything beyond 9", I really can't get aggressive before the motor starts to bog and the blank slows down. I'm only using a 3/8" bowl gouge, fingernail grind, 100% motor power, speed reduced by the reeves drive. On green hardwoods like ash or maple, I can barely get a 1/8" push cut going before I have to let off. It just takes extra time to rough out. I'm looking to purchase a bigger gouge to speed things up, but I've held off simply because I don't think I have enough motor. The VFD I think can go up to a 3hp, and it's a jack shaft version, so I think I could swap the motor - I'm just wondering if I should. Has anyone done that, or is there something else I could do to ease the bogging problem (technique, tooling, etc) or just live with it until my bowls buy me a Robust.

    The Reeves drive has a mind of it's own - It stays in the slowest speed setting, but pushing it up 1/4 turn results in it not staying put and it increases speed slowly from there to about 3/4. It takes a couple minutes, but it's like turning with a runaway train as the speed increases. The only thing I did to this was take out the limit switch on the inside, but I doubt that had any effect on this. I was thinking about roughing up the contact areas or installing some sort of locking lever to the casing. Again, just wondering if anyone else had this problem or have come up with a solution.

    Thanks.

  2. #2
    Join Date
    Oct 2008
    Location
    Kapolei Hawaii
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    2,773
    If you have a VFD, why are you using the Reeves? Just asking for trouble.

  3. #3
    Quote Originally Posted by Kyle Iwamoto View Post
    If you have a VFD, why are you using the Reeves? Just asking for trouble.
    Mostly because it's there and I see no good reason to strip it and put in a pulley and belt. Sure, the VFD could slow the speed way down on it's own, but with the Reeves it allows me to run the motor at full power while still going relatively slow and still gives me a high speed top end when finishing and doing spindle work. I've tried slowest speeds with VFD and high speed on the Reeves (mimicking what you'd have with a swapped out pulley) and there's even less torque because the motor's only running with 10-20% power. If you're implying that the Reeves is sucking horsepower, that'd be a reason to get rid of it, but I don't see how that's the issue.

  4. #4
    Join Date
    Feb 2018
    Location
    Sparta Tn
    Posts
    213
    sounds like something screwy with your VFD. You won't be able to take huge cuts with a 1 horse motor but with the reeves drive in the middle somewhere you should have enough pull to take at least 1/2" cut if you don't push the tool tool hard. That being said I love the bigger motor on my powermatic. On my Delta Midi which has a 1 horse motor with a DC drive I can still take moderate cuts on a 9" bowl and it should in theory have less power when I reduce the speed than a VFD will give.

  5. #5
    Join Date
    Oct 2008
    Location
    Kapolei Hawaii
    Posts
    2,773
    Yes, get rid of the Reeves. Lots of parts in there for the motor to spin. Or as John says, your VFD may be screwy. I've turned on a 1/2 hp Rikon and been able to get some decent cuts, so...........

  6. #6
    Sounds like the belts are slipping.

  7. #7
    Join Date
    Feb 2018
    Location
    Sparta Tn
    Posts
    213
    Yea I"d go with Dale on this one. That's certainly an easier thing to check.

  8. #8
    The Powermatic 90 has a robust reeves drive, unlike some of the finger laced pulley systems. The PM 90 uses a belt about 1.5 inches wide. The belt will last for a long time, but it does wear. As it wears, the belt gets narrower and harder. The narrow belt causes the system to not tension the belt properly and the hardness increase coupled with the loss of tension allows for belt slippage.

    OP, you might try putting the reeves into a position about 20% up from slowest and bring the spindle rpm's back down with the inverter. This will place the belt in a larger diameter area of the drive pulley and should allow more power to be transmitted by the belt.

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