Howdy Fellow IH'ers,
Some time back, I did the belt drive conversion on my IH and then complained about loosing all my low end torque. I had some things to learn and bought the motor & VFD before doing my proper home work. There were a few others talking motors and VFD'd but I didn't fully understand what they were telling me !
First off I started with a motor recommendation that was 2hp, 3470rpm motor and I thought to myself, SELF ! ( this parts gets me into lots of trouble) I want to increase my top end speed !
I also purchased a Hitachi L200 vfd. It is a good unit, BUT !
What I recently learned, and a few others was trying to tell me, and I really needed to know was this !
The 3470 motor falls into the 3600 group & is two pole, great for high speed, no low end torque.
next group is the 1800 or the 1740 motors, four pole ! ! ! This is the work horse motor for our needs. 1740 rpm's and lots of low end grunting torque !
then there is the 1200 6 pole, 800 8 pole etc.
Another thing I didn't know was that there is the std motor, and the inverter grade motor, which mainly is of a better grade of insulation and core bonding, wire etc.
Enough of that, but, If I had been able to read the above before I purchased my motor and vfd, I would have been much happier from the get go ! I could have made a more informed decision, that's why I'm posting this.
My 2 pole motor on the L200 ran great through the gear box, no problems. But when I went direct belt drive and eliminated the gear reductions, If I slowed the motor down to 20hz (20hz of 60 hz) I could grab the spindle with my hand and stall the motor, NOT GOOD !
OK, I just bought a four pole motor, C face mounting, still 2 hp.
Also bought a Hitachi SJ200 inverter drive which is the "Constant Torque" model, and started to test things out.
I left the 2 pole motor on machine and replaced the L200 with the SJ200 & set up the drive with the goodies turned on and set for two pole. I could still stall motor with hand and saw no real difference with drive and started worrying about $ spent.
I started the change over to the 4 pole motor, (used, non inverter) I had to make an adapter to extend shaft in order to eliminate the other shaft in box, then since the motor was C face mount I needed to be able to bolt to motor from inside of cover plate, then got it all assembled and mounted.
All I changed in vfd was from 2 pole to 4 pole then ran motor. Sounded great, I slowed it down to about 8hz which is about 230 rpm and tried grabbing the spindle.
I'M HAPPY TO SAY IT TRIED TO RIP THE PALM OFF MY HAND ! Now torque up the wazoo, I couldn't even hear an audible drop of rpm's.
Now I had my low end torque and could start to fine tune the inverter, but first, The SJ200 can over drive the motor from the 60 hz up to a limit of 400hz ! But, since my motor is not inverter graded and may have other limits, I chose to limit my input of 120hz, Now, I still have my 6000 rpm spindle and also my needed and wanted low end torque.
There are numerous smart and all knowing people on this site. And they knew all this stuff when I was just starting on this project. But, what I try to say above is not what they were saying and so I couldn't even put together an intelligent question in order to make sense of it all. I hope this can help someone who finds themselves in the position I was in then.
There is more yet to learn, more fine tuning of the vfd, more terminology to absorb, more questions to answer . . . . . . . . . .
I hope this makes it easier to understand, so maybe that someone, will not have to blunder the way I did, to learn what others consider to be fundamental !