vfd and motor ?

sgmtino

Well-Known Member
#1
So I just got back in to making knives and am going to be building a new belt grinder in the next couple months. What is everyones opinion on vfd's I am looking at possibly using a KBAC 27 and a 2hp motor I just dont know anything about this. I found what seems like a good price here
https://indsencon.com/products/kb-e...hp-ac-motor-made-in-usa?variant=1028357750797
Then I read somewhere that Leeson motors werent that good. I find 2hp 3 ph 1725 rpm baldor motors on ebay for around $200.00 this would also save me some money I think. Please give me your advice
 

KenH

Well-Known Member
#3
The drive wheel size of 4" will give you around 4,000 SFPM belt speed with a doubling jumper in that drive with a 1800 rpm motor. A 5" drive wheel will be "around" 5,000 SFPM, and a 6" drive wheel will be "around" 6,000 SFPM belt speed. Even with the 6" drive wheel I'd suspect the low belt speeds will still be slow enough. Even with the low power at 400 SFPM belt speed should have plenty of power.

Myself, I like a 4" wheel since that gives around 4,000 SFPM which is fast enough for a hobby maker like me. It will throw some sparks with a 36 grit ceramic belt.
 

John Wilson

Well-Known Member
#4
I’ve had great luck with that VFD and the low cost Ironhorse motors. A belt grinder simply doesn’t work a 2HP motor that hard. Starting and stopping quickly and constantly (short cycling / heat rise) like on a metering conveyor or machine infeed or discharge is what kills motors. Turning them on and letting them run is pretty much a perfect condition for a motor that is sized properly.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
#5
We use several of those KBAC27 drives here. They rock. I've had mixed results with Leeson's but I have had mixed results with every motor also. It looks like a fair price and you should be good to go.

I use a 4" drive wheel on all the grinders but for my grinder I use a 3450RPM motor and it absolutely screams when I want thick stock to go away in a hurry.
 

sgmtino

Well-Known Member
#9
Thanks for all the info guys. It will be afew months before I tackle the new grinder build so I'm sure I will have more questions.
 

sgmtino

Well-Known Member
#10
Ok my question on a kbac 27 what options here are necessary here are the choices on the website and i have no clue what any of these options are for or if they are necessary.Anny help here would be great
Forward-Stop-Reverse Switch: NONE FSR Switch 9480
On/Off AC Line Switch: NONE ON/OFF Line Switch 9523
Signal Isolator Options: NONE P/N: 9600- Signal Isolator without Auto/Manual Switch P/N: 9605- Signal Isolator with Auto/Manual Switch
AC Line Filter: (1-2 Day lead time): NONE P/N: 9512
Liquidtight Fittings:
 

KenH

Well-Known Member
#11
use a 4" drive wheel on all the grinders but for my grinder I use a 3450RPM motor and it absolutely screams when I want thick stock to go away in a hurry.
Are you using the KBAC drive doubler jumper on the 3450 RPM motor to get higher RPM? I run a 3450 RPM motor also with a 4" drive wheel which gives me around 4,000 SFPM belt speed which is plenty for me. Some other folks say they MUST have at least 6,000 SFPM belt speed to make ceramic belts really work.

I also use the cheap Chinese VFD drives with good luck. Just have to put filters over the air inlets to protect insides from steel dust - but at $80 shipped they're cheap!
 

KenH

Well-Known Member
#12
Ok my question on a kbac 27 what options here are necessary here are the choices on the website and i have no clue what any of these options are for or if they are necessary.Anny help here would be great
Forward-Stop-Reverse Switch: NONE FSR Switch 9480
On/Off AC Line Switch: NONE ON/OFF Line Switch 9523
Signal Isolator Options: NONE P/N: 9600- Signal Isolator without Auto/Manual Switch P/N: 9605- Signal Isolator with Auto/Manual Switch
AC Line Filter: (1-2 Day lead time): NONE P/N: 9512
Liquidtight Fittings:
I'd think the ON/OFF/REVERSE switch is really needed. If you can run the grinder in forward and reverse, then you've got everything lined up nicely.

I'd think the ON/OFF switch wouldn't be needed if you've got the reverse option switch.

Nope, you won't need the AC line filters nor Signal isolator for the short power run you'll be using. Those are used for long power runs of a few hundred feet to prevent standing waves causing excessive voltage spikes on the motor.

Liquid Tight fittings - only if you plan to have wet stuff around, or you need a way to connect everything up. They don't hurt a thing and do provide a good installation.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
#14
I use the motor wiring to get it to double from 1750. The motor I used just had the option so I used it. I do intentionally look for 3450RPM motors for grinders tho.

You are right about the ceramic belts liking that higher speed. I start with those as fast as I can handle and then switch to zirc's when I slow things down.

Do you have link for the chinese VFDs? I'd like to have a look.

Are you using the KBAC drive doubler jumper on the 3450 RPM motor to get higher RPM? I run a 3450 RPM motor also with a 4" drive wheel which gives me around 4,000 SFPM belt speed which is plenty for me. Some other folks say they MUST have at least 6,000 SFPM belt speed to make ceramic belts really work.

I also use the cheap Chinese VFD drives with good luck. Just have to put filters over the air inlets to protect insides from steel dust - but at $80 shipped they're cheap!
 

scott.livesey

Dealer - Purveyor
#16
So I just got back in to making knives and am going to be building a new belt grinder in the next couple months. What is everyones opinion on vfd's I am looking at possibly using a KBAC 27 and a 2hp motor I just dont know anything about this. I found what seems like a good price here
https://indsencon.com/products/kb-e...hp-ac-motor-made-in-usa?variant=1028357750797
Then I read somewhere that Leeson motors werent that good. I find 2hp 3 ph 1725 rpm baldor motors on ebay for around $200.00 this would also save me some money I think. Please give me your advice
do you have any electrical repair experience? if no, buy a KBAC and a Baldor motor, find someone to make and install the wiring. if yes, get a TECO or Marathon or Fuji or Hitachi. get a motor, baldor, leeson, us motors, marathon, .........
make sure you shop is wired with 240 vac which you will need to run a 2hp motor. get two drive wheels, a 6" and a 3".
 

scott.livesey

Dealer - Purveyor
#17
I use the motor wiring to get it to double from 1750. The motor I used just had the option so I used it. I do intentionally look for 3450RPM motors for grinders tho.

You are right about the ceramic belts liking that higher speed. I start with those as fast as I can handle and then switch to zirc's when I slow things down.

Do you have link for the chinese VFDs? I'd like to have a look.
nothing for chinese, but these folks have good selection and excellent service https://dealerselectric.com/variable-frequency-drive-motor-control.asp
next motor to look for Boss would be an 800 rpm, with a 3" drive wheel, your sfpm at 50% is less than 400
 

KenH

Well-Known Member
#18
I agree with Boss, duck seal (plumber's putty) works just fine for sealing holes and less expensive.

Boss, I'm not sure how you can change a 1750 rpm motor to 3500 rpm just by changing the wiring around. The motor rpm is determined by the number of poles the motor is built with. 2 poles, 3600 rpm, 4 poles 1800 rpm - you can change from low voltage to high voltage with wire changes. Like you, I sorta prefer a 3600 rpm motor vs the 1800 rpm motor for a grinder. Folks talk about torque is higher on the 1800 rpm, but that's only at lower rpm and you're not "hogging" at lower rpms so don't need the torque.

On the Chinese VFD drives you don't have a jumper to change, you just set max freq to be used with determines motor RPM. This like should get you to the last VFD I purchased. $80 shipped for a 2 hp, got a very good English manual of just a few pages, but all that's needed to setup. About the easiest VFD I've ever setup, and I've set up quite a few in industry.

https://www.ebay.com/itm/232756241295
 

sgmtino

Well-Known Member
#19
Thanks for all the info keep it coming. I do have a friend who is an electrician so worst case he could wire it for me. I appreciate the link to the teco vfd and the chinese one. I just want to make sure i get something im not going to have to scott.livesey have you used these drives and motors cause that is cheaper than just buying a KBAC27 I assume it will have to be put in an enclosure though right.
 

KenH

Well-Known Member
#20
If you use any open enclosure VFD you'll have to put in an enclosure, OR put filters over the air inlets. Filter is what I use, just cut some AC filter stuff and wrap around the existing enclosure seems to work pretty good. I've been doing that for 3 or 4 yrs now and same VFD still going strong. Understand, this is for hobby use - NOT a full time commercial use where the grinder is running 8 hr/day 5 days/wk.

My thinking was use the $80 VFD and if it went bad too quick, I could then look at spending the money for a KABC NEMA 4 drive. I use the IronHorse motors - a 2 hp, 3600 rpm 3 ph is around $160 shipped.... Just checked and it's $152 shipped: https://goo.gl/fdAC83
 
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