Grinder Motor Question

Dennis Towns

Dennis Towns

Joined
Jun 8, 2006
Messages
254
I have ordered a frame for my 2" x 72" grinder from one of the suppliers. I knew I had some Baldor 3 Phase motors , my question is , the only one I have that I think might work is 3hp and 1725 rpms. Here is a link to its specs http://www.baldor.com/catalog/VM3611 will this work for my grinder ? I have some other motors even new but not 3 Phase and I want to make it a variable speed. Thanks for input.
 
cootersplace said:
I have ordered a frame for my 2" x 72" grinder from one of the suppliers.
I knew I had some Baldor 3 Phase motors , my question is , the only one I have that I think might work is 3hp and 1725 rpms. Here is a link to its specs http://www.baldor.com/catalog/VM3611 will this work for my grinder ? I have some other motors even new but not 3 Phase and I want to make it a variable speed. Thanks for input.
Click to expand...
Should we try and guess which grinder ?
 
3 things jump out from the specs:

184C frame size. I think most of the 2" x 72" grinders are designed for a 56C frame size. Will it fit the grinder frame?.

7/8" shaft size. I think most of the 2" x 72" grinders are designed for a 5/8 shaft (which is standard for the 56C frame size). Will the drive wheel fit?

Inverter code = "not inverter". The output stage of a VFD is an inverter and it gives a much less "clean" waveform than mains power. The drawings in the .pdf linked from the spec sheet are dated 1999, and the insulation is class F, so there's a pretty good chance it'll run ok on a VFD, but it looks like the manufacturer doesn't recommend it. There's a risk if you do use it with a VFD that the insulation will break down quickly.


If you modify things to use the motor you have and it subsequently fails, will the modifications make it more difficult/expensive to source an inverter-rated replacement?

A 3HP motor will need a 3HP VFD. What are the cost implications for this?
 
The bolt pattern is larger on the 184c frame. The shaft diameter is the simplest problem to solve. You can get 7/8" drive wheels.
 
Yes the drive wheels are available for the 7/8 shaft. But timgunn1962 pointed out some things I didn't consider. The frame I ordered was the grinder in the box. I figured the bolt pattern was not an issue, I am not a schooled machinist but I have a machine shop and find my way around it for some things. I can dig out another motor I have and see what it is, I know its not a 3 Phase . So in some opinions what is the ideal motor to put the variable on? I wanted to do direct drive and not step pulleys . I appreciate all the inputs.
 
It all depends on what grinder you bought. My motor is a 3HP Baldor with a 182T frame, I believe, and that works just fine for me. But I have a KMG and do not mount my motor to the grinder frame.

-Clint
 
This is all new to me as far as what will or will not work. I did find this motor for sale not sure if I can put a variable unit on it.
00g0g_9f1RAOk1tu5_1200x900.jpg
 
cootersplace said:
This is all new to me as far as what will or will not work. I did find this motor for sale not sure if I can put a variable unit on it.
00g0g_9f1RAOk1tu5_1200x900.jpg
Click to expand...
Thats a singlephase motor, it can run variable speed to a minor degree but not in a fashion useful to a knifegrinder.
Its ODP enclosure, "open drip proof". It has minimal protection against dirty/abrasive environment of a grinding machine.
Keep looking. At minimum, Three phase and TEFC must be shown on its nameplate.
 
Last edited:
best bet is see if person who sold you the grinder kit will replace the part drilled for a 56C frame(mounting holes are a 5.875" circle) with a part drilled for a 184C frame(mounting holes are a 7.25" circle). We don't know without seeing the grinder if there is enough room to redrill the holes. getting a different motor mount part will cost a whole lot less than a new motor. But wait until you have received kit and are sure it won't fit. the print attached to your Baldor link is confusing, says 184c but dimensions are the same as 145C
 
Last edited:
The only issue maybe, is finding what I need to fit the shaft. The motor shaft is 1 1/8" so I may need to turn a reducer for it.
 
has the grinder arrived? check the plate where the motor mounts and see if the Baldor motor fits. if it does not, is the mount big enough to allow new holes?
 
I may be ordering a different grinder or frame. The poor fellow with the GIB has been having some problems. I am going to wait for another week and see. In the mean time I have stumbled across another motor. Here is a couple pics. It says it is 3 phase and reversible not that I need it.It is also 3 hp like the other 3 phase Baldor but it is smaller. One has the mounting bolts on face the other has a mounting base on bottom. Guess I could always weld a base on grinder frame. Here is the newest find. Is it a good fit ?
 

Attachments

  • Motor 3.jpeg
    Motor 3.jpeg
    85.7 KB · Views: 3
  • Motor 4.jpeg
    Motor 4.jpeg
    58.8 KB · Views: 2
So even if I have to do some welding or machining, I have 3= 3 HP motors, one is brand spanking new in wrapper and is single phase 220 big shaft 1 1/8" the other 2 = are 3 phase one has face mounting the other bottom base. The face mounting one has a 1" shaft the other has I think 5/8" and I am going to put variable control. I have a heck of a bunch of power. I might build 2 grinders.:)
 
You must log in or register to reply here.
Back
Top