1 HP direct drive vs 1.5 HP 3 step pulley

AVigil

Adam Vigil knifemaker working the grind
Knifemaker / Craftsman / Service Provider
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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
 
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.
 
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.

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?
 
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?
No noticeable difference at lower speeds and general light grinding.
 
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.
 
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.
 
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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.
 
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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.
 
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.
 
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