1 HP direct drive vs 1.5 HP 3 step pulley

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by AVigil, Feb 8, 2021.

  1. AVigil

    AVigil Adam Vigil knifemaker working the grind Platinum Member

    Feb 17, 2009
    Since the beginning I have been running a 1.5 hp 1800 rpm set up on my grinder with 3 step pulleys. It has worked great but I am wanting to tilt for horizontal grinding and considering a direct drive.

    My question is, how will a direct drive VFD 1 hp 1800 rpm compare to the 3 step pulley set up I am currently using?

    Note: I know I could go for 1.5hp with VFD. The difference in price is $200
  2. HSC ///

    HSC ///

    Nov 7, 2012
    I think the answer depends on how you grind and what you grind.
    You moved to folder blades . I don’t think you will notice any practical difference

    you will notice more a positive difference of the infinite control of a vfd

    with that said, in general I have found you never regret overbuying. So always get the big one.
    Alpha Knife Supply and Scaniaman like this.
  3. AVigil

    AVigil Adam Vigil knifemaker working the grind Platinum Member

    Feb 17, 2009
    Really the only reason I will change to a direct drive is to go slower and to tilt the grinder.

    I just wonder what the actually "power" difference is between a 1hp direct drive and a 1.5 hp with a step pulley?
  4. HSC ///

    HSC ///

    Nov 7, 2012
    No noticeable difference at lower speeds and general light grinding.
    AVigil likes this.
  5. AVigil

    AVigil Adam Vigil knifemaker working the grind Platinum Member

    Feb 17, 2009
    I will just have to go for the 1.5 hp when I upgrade to avoid the regret of not doing so
  6. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Yes, at your more advanced skill level you will be happier with 1.5HP and a VFD. 1Hp will work just fine, but you do enough shaping and beveling to want the extra oomph.
  7. scherf68

    scherf68 Basic Member Basic Member

    Feb 12, 2020
    I am in same boat, wanting to know same question and may just save for the 1.5 hp vfd at 110. My understanding is that 1.5hp/110 can be rewired for 2 hp for 220. I was going off Ameribrade kits, the difference in price is 300 but I can pick up and save on shipping. I have been direct drive 1800 rpm changing drive wheels (4 in and 7in), a hassle but doable. The 110 kit is enticing but limited to 110 and 1 hp but people love my thick cleavers and a bear to grind down. I have 220 in shop but limited to just one outlet being used with amperes.
    Last edited: Feb 10, 2021
  8. Hubert S.

    Hubert S. Gold Member Gold Member

    Dec 14, 2019
    With the KBAC-27D VFD, you can run a 2HP motor at 110V and it will give you 1.5HP and can be wired to give 2HP at 220V. But you need a 2HP motor to start with.
    Ken H> and 12345678910 like this.
  9. Britt_Askew

    Britt_Askew Dealer / Materials Provider Knifemaker / Craftsman / Service Provider Dealer / Materials Provider

    Dec 9, 2010
    A few months ago my grinder started acting up. I was running a 1 1/2hp motor and had a 1hp motor on the shelf that I switched to see if it was the motor of the vfd. Turns out it was the vfd. ( it would stop running after a while)
    I couldnt tell any difference in grinding between the 2 but didnt do any hogging. Both were direct drive though.
    Last edited: Feb 11, 2021
  10. Drew Riley

    Drew Riley Riley Knife and Tool Knifemaker / Craftsman / Service Provider

    Oct 17, 2007
    Given only those two options, I’d take 1hp with VFD all day.

    That said, I’d keep an eye out for a better price on a 1.5 to 2hp 3 phase motor. They often pop up for well under $100. The VFD may be another story, though you can get by with a cheap vfd for under $100 as well, while you save up for an upgrade. You’ll need 220vac for the input though.
  11. David Schott

    David Schott

    Sep 27, 2004
    Shop craigslist for motors and get a more capable VFD. I got a 3hp 3phase Baldor for $30 with wiring. I dont think there's any issue getting a larger VFD that can handle a bigger motor if you find one (other than the price) so you could future-proof.

    I dont think there's a big market for sub-5hp three phase motors, at least to general homeowners so I've found they can be cheap as hell on craigslist if someone has one lying around. I was a cheapskate and went chinese VFD but couldn't beat 3hp VFC/motor combo for under $150 total. The VFD seems fine so far but with my feeble attempts at sealing it, I want to see how long it will last being that it was less than 1/3 the price of the KBAC.

    Be sure to calculate your belt speed. With a standard drive wheel set up for a 3 step pulley, motors tend to be 1750 RPM. If you're running 1:1 with the VFD you'd need a larger drive wheel or a higher RPM motor, I think. I ended up with a hybrid setup where I effectively "fixed" my pulley setup at a ratio that allowed me to stick with my old drive wheel. I have plans to eventually step up to a larger drive wheel and to put a lovejoy connector on the motor/driveshaft to effectively make it direct drive vs even having the pulley.

    If I had found a dirt cheap 3Hp that was a 3000+ rpm it may have been a better immediate fit for overall speed but I actually find myself wanting more for low speed torque than top end belt speed so the 1750 hasnt left me wanting at all just yet.
  12. Ken H>

    Ken H>

    Dec 31, 2011
    Well, how many would you actually have running at the same time??

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