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VFD vs Rotary Phase Converter

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  • VFD vs Rotary Phase Converter

    During the covid stuff, I've added some 3ph machines to my 1ph-powered metal shop. 1hp mill, 1hp ancient lathe and 3hp Gairu (pullmax). VFD seems to be the "best" option, as well as the most expensive option by far. So I have been planning to assemble a proper rotary phase converter to provide a 3ph circuit for my shop and not have to wait until ?? to afford having my shop running.

    I had planned to do a 5hp rotary phase converter vs a larger and more $$ factory-built 10hp rotary converter a local friend has. My shop is small enough that it is already clogged, so planning for growth & adding machines in the future is not as relevant. It's hard to envision where a 5hp-7hp machine would fit in my shop to necessitate the 10hp converter. It's unlikely that multiple machines will be running at the same time because it's just me. A vfd on my Gairu makes the most sense and might be a future upgrade. Taking it off of the 3ph circuit, long term added costs of running a 10hp converter to only power a 1hp motor may be nominal (?) but seem wasteful to me.

    Bums me out to not post here as often or easily as other places. my budget has been going towards the shop instead of a newer ipad that can be updated so I can log in here & other places. My old ipad is near death.

    If anyone here can share their experience and actual btdt advice- especially about real costs, not once in a lifetime bargain deals- please do. Thanks, guys.

  • #2
    VFD's are expensive, but so nice. I have one on my mill with a control for the speed. Instead of cranking the handle several time, just turn the knob a wee bit and she changes.

    I've even used one on our drill press at work. This is quite terrific as we never need to move the belts any more. Instant speed changes using the speed control knob. (it's not actually speed control, but HZ control, I believe). We were able to use a 240 volt 3 phase motor plugged into a 120 volt outlet. Sweet.

    However, all that said and the fact that you would need three, a phase converter sounds like the logical $$$ choice.

    I believe each VFD was around $150.00 USD.
    Link below. The 3 HP will be costly.

    AC Drives and VFDs for Any Application Available. Authorized Distributor of Top Brands. Get Free Shipping on $100+ Orders!


    • cliffrod
      cliffrod commented
      Editing a comment
      Thanks, Pugsy. Having variable speed on my Gairu makes a vfd for it the most practical. The others, probably not. Still thinking and planning.