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spinning bits

Discussion in 'General Talk' started by sw3Dp, Jun 9, 2015.

  1. sw3Dp

    sw3Dp New
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    Now onto the spindle ... right now I have a $10 black-n-decker 1.5hp router but it has it's own ps. I will only use it to cut the spoiler board and tests in mdf scraps, if it works. Eventually, I was hoping to be able to efficiently face aluminum plate. I still have the limit of 120v in the shop and was told the max spindle wattage possible is 750w with a vfd. There are plenty of 800w-2.2kw spindles being bundled with vfd that have the 120v switch. My question is will a 2.2kw spindle being powered with the 120v vfd produce the same 'milling power' of a 600-750w spindle motor? Costs being equivalent is there a reason I shouldn't get the 2.2kw 'silent spindle' verses the 600w 'jet engine'? ( I spent a few hours googling with no luck but might be miss using terminology.)
     
  2. Joe Santarsiero

    Joe Santarsiero OB addict
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    If the inverter does 110V to 220v and is at or above the spindle wattage and current ratings, then you're good to go. If the spindle is specd higher than the vfd then you may have problems getting the spindle to start or stay running in a cut.
    The problem with using the higher wattage spindles on a 110 is that there is more current drawn than on a 220. This starts to approach breaker capacity (20A common in the US) and/or capacity of the inverter. Using a spindle with a higher current rating than the vfd is capable of will result in current overload, motor protection faults, among other problems like stoping midcut, and possibly blue smoke.
    Pay attention to the total current you're using on a breaker. As stated, a 220 input vfd will reduce current draw. This is why 1 and 2hp 120V vfds are common and the market jumps to 220V inputs around this range and above. You shouldn't have a problem with a 1 or 2hp (.8 and 1.5kw) spindle on a 110v 20Amp breaker. If you're wanting to get the 2.2kw spindle because of "getting the upgrade now" then be forewarned that you may being having some headaches later on when it comes to powering it.
    I'm positive that you'll be plenty happy with a .8 or a 1.5kw with a 110V to 220V vfd as long as your gantry, drive system, and joints can handle it. You can stand right next to it and talk on the phone at room levels.
    Ignore hand and trim router hp ratings. Look at the amp rating instead.
    Imo, beyond initial setup, you'll be much happier with just an 800w spindle over a 600w router.
    If you do end up with one, then make sure you set the min. freq. to the spindles min. rpm. And used balanced tooling to reduce bearing wear.

    Joe
     
  3. sw3Dp

    sw3Dp New
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    Thanks again Joe, good explanation and I will take your advice about the 800w spindle when the upgrade happens. I was planning water cooled because the cnc will be boxed for sound and debris control.

    I have been lucky with Chinese parts, knock wood, but on the spindle packages you have to wonder if they make it "work" for 120v without really working. It wasn't until building a machine that I really started to hate the 120v wiring. My yard sale router is actually 1.25hp 8.5amps and requires hearing protection but just needs to survive the gcode learning curve. The garage has a single 20a breaker (for the whole machine, lights, exhaust fans, about 14amps apollo 13 style) ... looks like it's time to unplug the window ac.

    jack
     
  4. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Got a 220v clothes dryer outlet out there?
     
  5. sw3Dp

    sw3Dp New
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    nope, 100m from the box, out structure, 19th century 'craftsman' house rewired 50's. I got the "discontinued pushmatic breaker box they don't even make parts for those anymore ... you'll need a permit ... $5k for new service," from a couple electricians. I could pick up a 40a breaker on ebay $10 and just run the line myself but if the garage burns down, home insurance won't cover it. If I overload a 20a I'm covered, go figure.
     
  6. Joe Santarsiero

    Joe Santarsiero OB addict
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    "Ignore hand and trim router hp ratings. Look at the amp rating instead."
    I should've added "when comparing router vs router".
    Spindles ratings are based on RMS while routers are based on manufacturer testing. Adding, the brushed motors used in routers are much less efficient and require more current. They don't last as long either. They can be rebuilt and upgraded. I have read stories over on the zone about short lived chinese spindles. Bad bearings, disconnected ground, leaky water jackets mainly(replaced by the seller in most cases).
    If you can get a 220 for your shop, then go for it OR use a dryer outlet like Rick mentioned. If not you'll be good with a .8 or 1.5.
     

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