Phase converter for dual motor surface grinder
Close
Login to Your Account
Results 1 to 8 of 8
  1. #1
    Join Date
    Feb 2018
    Country
    UNITED STATES
    State/Province
    North Carolina
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    8

    Default Phase converter for dual motor surface grinder

    This is probably a dumb question, but I am no expert on electric systems.
    I have a new to me Boyar Schultz 2A618 surface grinder. It has a 1hp spindle motor, and a 1/2hp hydraulic motor. I have a shop full of 3 phase machines, running off of various VFDs, but have not considered whether I can use another on the surface grinder, as both motors run at the same time.
    Any advice?

    T

  2. #2
    Join Date
    Jul 2007
    Location
    Missoula Mt
    Posts
    1,270
    Post Thanks / Like
    Likes (Given)
    55
    Likes (Received)
    566

    Default

    Sure 2 hp rfc would work just fine...Phil

  3. Likes JST liked this post
  4. #3
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    19,070
    Post Thanks / Like
    Likes (Given)
    2292
    Likes (Received)
    3534

    Default

    yep, an RPC would be perfect for the job!

  5. #4
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    19,094
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    11679

    Default

    Quote Originally Posted by toadboy65 View Post
    This is probably a dumb question, but I am no expert on electric systems.
    I have a new to me Boyar Schultz 2A618 surface grinder. It has a 1hp spindle motor, and a 1/2hp hydraulic motor. I have a shop full of 3 phase machines, running off of various VFDs, but have not considered whether I can use another on the surface grinder, as both motors run at the same time.
    Any advice?

    T
    If you are already "married" to VFD's, just buy two more.

    "A shop full of... 3-P", and NOT also "full of simultaneous operators" ... WAS the ideal use for an RPC. Or maybe even a Phase-Perfect.

    Too late now? Noo.. WHEN the VFD's start crapping out, have damaged an older motor or two, need new caps or the odd dv/dt filter?

    You get a second chance!



    More seriously, ONE new VFD, and ONE new single-phase juice pump.

    They are cheap and cheerful, 1xx, 2xx VAC 1-P .. or strappable for either.

    Plug that puppy into your ordinary outlets. Sort whatever you need for switch or relay.
    Last edited by thermite; 02-28-2021 at 06:40 PM.

  6. #5
    Join Date
    Feb 2018
    Country
    UNITED STATES
    State/Province
    North Carolina
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    8

    Default

    I pretty much run one machine at a time. It is not like I am in love with VFDs. 3 phase power is not an option due to location, and I built the shop with smaller tools in mind, but with lots of space.
    Then I started accumulating larger tools. First was a 16x40 lathe, and I ended up getting an expensive(for me) Hitachi VFD. But the tools keep coming. Good tools for scrap prices or less. It is not like I am following a plan, where I might have been able to predict my usage and prepare for it.
    When I got my big mill, I just built a little box with a 2 position switch and a couple of magnetic relays, to let me switch between the mill and the lathe, since they are next to each other, and have similar power requirements. The VFD control head is on a hinged arm, and can be swung over to either tool.
    I thought about doing the same with the surface grinder and my 12 inch lathe, as the total HP (1.5) is the same, and the lathe already has a VFD.
    But a big issue is that I am sort of out of my comfort zone with 3 phase power and motors. I can pretty much follow the instructions on the box, but am a long way from really understanding the systems or being able to design them.
    I suppose the next step is figuring out how to match a new hydraulic power pack to the machine, or to try to bodge a 1ph motor into the old one.
    Thanks for the responses, they confirm my intuition.

  7. #6
    Join Date
    Sep 2009
    Location
    Phoenix,AZ
    Posts
    2,016
    Post Thanks / Like
    Likes (Given)
    3199
    Likes (Received)
    541

    Default

    If you are grinding for finish do NOT use a single phase motor ! finish will suffer. I noticed a improvement finish wise when I went from a static converter to a rotary. I ran both the spindle and hydraulic pump on a static 1-3 HP unit on my Boyer 618 2A when i first got it.

  8. #7
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    19,094
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    11679

    Default

    Quote Originally Posted by JohnEvans View Post
    If you are grinding for finish do NOT use a single phase motor ! finish will suffer.
    On a SPINDLE motor? Probably get a 'watermark"" on uber-fine work, yes. Won't even be noted on most work. Inertia exists. Single-phase motors are not "steppers", they are fairly smooth until close to overload.

    On a coolant pump? Not even relevant.

    On a hydraulic traverse power pack? Almost certainly not going to be detectable.

    Static converters do not. Convert.

    That sort of cluster-f**kery is not relevant to anything but uneven heating and rough running that shortens the life of a motor. Being tricked into running crippled on TWO "dropped phases", not just missing the one and at only around 30% power is more like playing hopscotch than steady strolling.

    Just don't DO that.

    Not even for a floor fan or a coolant pump.

  9. #8
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    19,070
    Post Thanks / Like
    Likes (Given)
    2292
    Likes (Received)
    3534

    Default

    Inertia exists, sure.

    So do torque variations.

    Some applications won't matter, some will. If the application is torque sensitive, typically run near top of motor capability, then the torque (and so, speed) variations will make a difference. Could be with grinding, often is with a lathe.

    I've never seen ANYONE say that they got a better finish going single phase... I have seen and experienced the reverse.

    To be fair, there is single phase and then there is single phase. Any "single phase" motor with a "run capacitor" is effectively two-phase, and so is substantially equivalent to three phase, if the run cap was well chosen by the maker. Such a motor will not have any large disadvantage vs three phase.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •