Motor Speed for 2x72 grinder

L

Lehbauer

Joined
Feb 16, 2022
Messages
68
First would just like to say, I'm sorry for having to start this thread out as I've read a bunch this morning, and am actually a lot more confused than when I started.

Been saving and selling off a few things that I no longer need to upgrade the 2x28 grinder I'm currently working with to a 2x72. I dont have 220 in the area, but I suppose I could look at it in the future possibly next summer. I have what I need to get the grinder body (Nexus Grinders is about 30 minutes away from me), but been waiting as I keep squirrelling away for a vfd/motor combination. Now that you have a bit of the background. here's my dilemma this morning. Princess Auto has their 1hp single phase 1750rpm motors on sale this week for $200. If I got that with the grinder, I could get grinding now, and keep saving for the bigger motor/vfd in the future. Also the 1hp could be then used for a flat disk later. If I use the linked calculator though https://www.productivity.com/resources/calculators/ the surface feet per minute with a 4" wheel is only 1886, or with a 5" wheel is still only 2358. based on other posts you need approximately 4000 for the ceramics to work?

How bad is this Idea I have to get myself something new and shiny, or should I just chill and keep using up the short belts? I still have some of my custom order belts to get me through a couple months more. I had to get them because no one uses a 2x28 except this guy, but getting frustrated with a poor setup.

Just for eye candy, latest couple I just finished up this week. 2-8" chef's knives a friend is giving as Christmas gifts. 80CRV2 with stabilized checen handles.

d5f468b2d9fb5ba532c1b59a7374528d.jpg
 
Ok, so search on Amazon for "motor vfd combo"

The first item that comes up for me is a vfd for 100$. 110v in 220v 3 phase out.

Another search for "3 phase motor" the second entry that comes up is a 1.5hp 3 phase 1750 RPM 56c TFEC motor for 219.

this is the combo that you want.

It gets you everything you want/need for 100$ more than a single speed 1hp motor.

An added benefit is that the vfd is good for up to 3hp, so if you decide to get a bigger motor later you can with no problems.

Is it perfect? No. You'll need to build an enclosure to keep the dust out of the VFD. But for the money it's just about exactly what you need...
 
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I agree with Andy. get a motor VFD combo and you will be set for a long time.

There is a seller on ebay that I use. A little more than getting all the parts and making up your own setup, but the products are top grade, and you can get everything wired and ready to go. That is especially important if you aren't a DIY sort of electrical person. Search - KB Electronics KBAC-27D, Techtop Motor & Drive Package Belt Grinder VFD 2X72 56C

Your choice on 1800 vs 3600 RPM. I like the 1800RPM motors, but other like the faster motor.
 
$200 for a 1ph, 1hp motor? Naw, almost enough to buy a 3ph 1,5 hp motor and use this 1ph 120 vac input VFD B0B1WDHNB9 or (B0B1WCRC56 is a 2hp) from Amazon for $105 shipped. I've NEVER used either of those VFDs, nor have I used a 120 vac input VFD. I suspect they'll be just fine as are the other Chinese VFDs used. I see on the part number I gave it's only got a 1 star review with no comments and only 1 person reviewing so I wouldn't put much stock in that single review. If I were needing a 120vac input VFD I'd sure take a chance.

From AutomationDirect you can purchase a 3ph motor per following
1.5 hp 3ph for $252 or
#MTRP-002-3BD36 which is a 2 hp, 3ph for $272 and I think it's free shipping on either of them.

The previous poster just beat me to it - I had forgot about the 3 ph motors on Amazon. 1.5 hp is the largest they have, but that will do.

"IF" you have the choice you might think about 3600 rpm motor unless the VFD has a "doubler" circuit to allow running motor at 3600 rpm. With a 4" drive wheel at 1800 rpm you're only getting 1885 SFPM belt speed. It would take an 8" drive wheel to get up to around 3800 SFPM belt speed.

We're both saying the same thing - go 3 ph w/VFD, the cost is only $100 to $150 more than your 1ph 1 hp motor.

Stacy got his post in without me seeing it.
 
Thanks Everyone.
I’m not that knowledgeable on the electronics side, but have access to a couple j-man industrial electricians. Maybe a case of beer or two and I’ll get them to wire it all up for me.
Shipping in Canada is what was keeping me from searching all the online options but free shipping US side and I can just make a quick trip into Montana. Looks like I’ll just wait a bit. Maybe pick up the grinder body and that’ll kick my ass into gear to get the rest done
 
Ken H> said:
$200 for a 1ph, 1hp motor? Naw, almost enough to buy a 3ph 1,5 hp motor and use this 1ph 120 vac input VFD B0B1WDHNB9 or (B0B1WCRC56 is a 2hp) from Amazon for $105 shipped. I've NEVER used either of those VFDs, nor have I used a 120 vac input VFD. I suspect they'll be just fine as are the other Chinese VFDs used. I see on the part number I gave it's only got a 1 star review with no comments and only 1 person reviewing so I wouldn't put much stock in that single review. If I were needing a 120vac input VFD I'd sure take a chance.

From AutomationDirect you can purchase a 3ph motor per following
1.5 hp 3ph for $252 or
#MTRP-002-3BD36 which is a 2 hp, 3ph for $272 and I think it's free shipping on either of them.

The previous poster just beat me to it - I had forgot about the 3 ph motors on Amazon. 1.5 hp is the largest they have, but that will do.

"IF" you have the choice you might think about 3600 rpm motor unless the VFD has a "doubler" circuit to allow running motor at 3600 rpm. With a 4" drive wheel at 1800 rpm you're only getting 1885 SFPM belt speed. It would take an 8" drive wheel to get up to around 3800 SFPM belt speed.

We're both saying the same thing - go 3 ph w/VFD, the cost is only $100 to $150 more than your 1ph 1 hp motor.

Stacy got his post in without me seeing it.
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Very helpful thread. I am new here and value the willingness of the community to help.
I am building a 2 X 72 grinder using a 2 HP 1800 230/3 ph inverter duty motor. 5 inch drive wheel.
Question: how can i tell if the VFD had the "doubler" circuit? I would like to overspeed the motor.
Thanks on advance,
Steve
 
radiored said:
Question: how can i tell if the VFD had the "doubler" circuit? I would like to overspeed the motor.
Click to expand...
Have you chosen a VFD yet?

Well, the KB27 series all have a doubler jumper - as far as I know anyway. If you're looking at the Chinese VFDs they all (that I'm aware of) have a freq setting where you can set the max speed to whatever you want, from 60 Hz (for motor base speed) to... I'm not sure of the max, but for sure doubling the speed is no problem. With a 3600 rpm motor I run around 63 Hz for a 3850 RPM motor. With your 1800 rpm motor you'd look for around 125 or so Hz.

With the 5" drive wheel you'll need around 3850 RPM for around 5,000 SFPM which is a good speed for max. I started with 4,000 SFPM thinking that was fast enough. As my skills/comfort level grew I moved to 5K SFPM and found it good.
 
Ken H> said:
Have you chosen a VFD yet?

Well, the KB27 series all have a doubler jumper - as far as I know anyway. If you're looking at the Chinese VFDs they all (that I'm aware of) have a freq setting where you can set the max speed to whatever you want, from 60 Hz (for motor base speed) to... I'm not sure of the max, but for sure doubling the speed is no problem. With a 3600 rpm motor I run around 63 Hz for a 3850 RPM motor. With your 1800 rpm motor you'd look for around 125 or so Hz.

With the 5" drive wheel you'll need around 3850 RPM for around 5,000 SFPM which is a good speed for max. I started with 4,000 SFPM thinking that was fast enough. As my skills/comfort level grew I moved to 5K SFPM and found it good.
Click to expand...
Hi Ken,
Thank-you for the very helpful response. I am leaning toward the KB27 series. The Chinese ones are tempting, currently $90-100 on Amazon, but they will need an enclosure.
Thanks again.
 
Lehbauer said:
Thanks Everyone.
I’m not that knowledgeable on the electronics side, but have access to a couple j-man industrial electricians. Maybe a case of beer or two and I’ll get them to wire it all up for me.
Shipping in Canada is what was keeping me from searching all the online options but free shipping US side and I can just make a quick trip into Montana. Looks like I’ll just wait a bit. Maybe pick up the grinder body and that’ll kick my ass into gear to get the rest done
Click to expand...
I did my VFD/2hp motor for my 2x72 about 5 years ago or so - if I can do it, you can do it.

Having said that, I would have gladly paid a case or two of beer to have a professional do it!

[thumbs up!]👍
 
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