new GIB motor question - HP and RPM specific

D

dperk

Joined
May 16, 2006
Messages
132
Hello everyone!

I have searched and read lots of posts, but I still am not sure which motor to order for my GIB setup.

I can do either 110 or 220v no problem. I was leaning towards 220 because my welder, air compressor and other shop tools are 220 already.

What I'm confused about is the RPM to choose. I see a lot of people like the 1.5hp for the ability to run it on 110, but I think I'm ok with the small cost difference to "upgrade" to 2hp and 220 IF it actually gains something useful. If there is not much to gain, then the 1.5 may make sense for convenience. So, I'm still thinking about running 220v and going 2hp.

What I'm not sure about is RPM of motor. I know you can double through the model 27 VFD, but why not just not-double and run it straight? I read a thread where someone said the low RPM motors are better built and more torque. That does make sense to me, but I wanted to ask the makers here.

Thanks for the advice, sorry if this has been asked before and I didn't catch it.

-darren
 
I'm going 2hp (DC) and 1750rpm with a VFD, but I'm using a pulley system to drive it, which means it should be easy to bump up the belt speed by putting a larger pulley on the motor.
 
I run a 1 HP DC drive with mine and never feel like I need more power. If I push hard enough to slow it down, the belts degrade quicker.
 
Go 220v, 2hp, 3450rpm, with a vfd. or 220v, 2hp, 1725rpm if no vfd.

I went with the first option and it is working GREAT!
 
Speed of motor all depends on drive wheel diameter.
I have found that if you are going the vfd route you would be foolish to go anything
But 3600rpm using a 4" drive wheel. You can always slow it Dow via vfd.
If your going fixed speed 3600 is just right for me in coarse grits but a little fast for fine grit belts.
Perfect compromise might be a 6" wheel on a 1800rpm motor.
Cw
 
If you are setting up a single machine in your shop, variable speed is a must. There is no substitute for horse power. I run two KMG's one with a 2hp,1725rpm, 110 motor with 2-3-4 pulleys and a 6 inch drive wheel. It runs slow enough on the 2 inch to sharpen blades and at 5400 SFM on the top end for grinding bevels.
I have a second KMG set up with a 3 hp 1725 220 volt machine with the 6 inch drive wheel. It runs the same belt speeds as the 2 hp the only difference is you can not slow it up when grinding bevels. There is no substitute for horse power.
I have a 1 hp variable speed dc motor Pro-Cut machine that I use for finishing handles it does not have enough power for heavy grinding.

Good luck with your new machine, Fred
 
blindhogg said:
Speed of motor all depends on drive wheel diameter.
I have found that if you are going the vfd route you would be foolish to go anything
But 3600rpm using a 4" drive wheel. You can always slow it Dow via vfd.
If your going fixed speed 3600 is just right for me in coarse grits but a little fast for fine grit belts.
Perfect compromise might be a 6" wheel on a 1800rpm motor.
Cw
Click to expand...

You can also speed it up via like you said via VFD.... I went with a 1725 RPM motor 4" wheel, and VFD with the 2x speed selected... So I have the 3,450 RPMS..... I'd say it also depends on what motors you have available...
 
blindhogg said:
Speed of motor all depends on drive wheel diameter.
I have found that if you are going the vfd route you would be foolish to go anything
But 3600rpm using a 4" drive wheel. You can always slow it Dow via vfd.
If your going fixed speed 3600 is just right for me in coarse grits but a little fast for fine grit belts.
Perfect compromise might be a 6" wheel on a 1800rpm motor.
Cw
Click to expand...

If you read the kbac27d manual, there is a chart there of speed vs torque for a TEFC motor
as rpms drop, so does torque - rapidly


If you are choosing between these 2 scenarios,
I would pick the high speed motor and the smaller drive pulley


When comparing those 2 setups and the same belt speed in SFPM
It will allow you to keep the motor rpm relatively higher and so the torque.



but

If the difference is getting one motor used for a song & paying full retail for the other
I'd go cheaper & doubt you will have any problems with either setup.
When you are using low speed for finishing, you are probably using a light touch anyway so torque won't really be a problem.

&
There are likely many many more 1,700 rpm motors available.
 
I use a 3 phase 3hp high speed motor with a 5hp Allen Bradly VFD that I got from Southland Electric. They get used industrial equipment, make it like brand new, and warranty it like it's brand new. If it breaks, they fix it themselves, of course. I got the 3 phase motor for free, which is aproximately the going rate for 3 phase motors, and the monsterous VFD was about $500, I believe.

With the 10" drive wheel on the Coote, I used 1:2 pulleys to slow it down. I have zero complaints about anything. I obviously have no complaints about my TW-90, but the power is comparable.

I agree, no substitute for horse power. Even though you don't use it all, your equipment will last longer if it doesn't have to work so hard.
 
Thanks for all the input everyone!

I think I'm leaning towards a 3450 RPM 2HP 3PH 220v motor with a VFD and using a 4" drive wheel.

I was just searching locally and found this Baldor motor slightly used for $99:

Baldor2HP.JPG
 
dperk said:
Thanks for all the input everyone!

I think I'm leaning towards a 3450 RPM 2HP 3PH 220v motor with a VFD and using a 4" drive wheel.

I was just searching locally and found this Baldor motor slightly used for $99:

Baldor2HP.JPG
Click to expand...

Go with that:thumbup: I went with a Leeson 1.5hp 3ph and VFD, because I got my motor for $50 on Kijiji. The guy didn't know about VFDs and said that there was no way he could use it so he was selling it cheap, it cam out of a brand new table saw and had barely been used
DSC01817.jpg
 
You must log in or register to reply here.
Back
Top