Hi Mike, thanks for the note. Sorry that I could talk more on the phone last night. Me and the family were heading out for dinner.
There are tons of VFDs...and I'm sure it's overwhelming. You'll get lots of opinions and of course your final decision will also be based on your budget.
My 1st choice would a KB..either a 27D or 24D depending on the size of your spindle motor. The 24D would be for a 1hp...and the 27D would be for both 1-1/2 and 2 hp. I like this drive because of the enclosure and exterior controls. It's a "wash down" enclosure which you can actually spray with a pressure washer. The exterior controls are simple and easy to use...no touch pad with several layers of menus. But it's more $ than most others.
On your mill, you'll want reversibilty. There's a couple ways to do this. 1st, you need to use the controlls on the VFD to start and stop the motor. Don't use the VFD as a power supply to the switch on the mill...where you turn the mill on by that switch. The VFD needs to controll the starting and stopping of the motor. For reversing, you can use the VFD for this..but depending on the unit, you might need to punch through a few menus on a key pad which will be a pain....so, you could use the rotary drum switch on your mill to select a forward or reverse before sarting the spindle by the VFD. Basically, you will flip the drum switch to either FWD or Rev 1st...then start the spindle with the VFD.
If the VFD has a front panel reversing switch...like available on the KB units, you can switch it on the fly which will allow you to tap parts with the spindle under power.
I personally would'nt count on using the VFD for speed controll...maybe a little...but use the Head speed settings either belt position or varispeed. The reason is that you'll want the motor running at it's peak power...which happens at it's designed (name plate) speed. Slower spindle speeds in the mill imply a bigger cutter diameter, and/or harder material...so you'll want as much power as you can get especially at slow speeds. .... Set the head in the slow speed position and run the motor at it's designed speed by the VFD. Cutting the motor speed in half will also cut the HP in half...and so one.
Make sure your VFD is rated for your motor HP or more when it is using single phase input. Many VFDs will run on either single phase or 3 phase....but when they are set for single phase, thier output is derated.
I think I would plan to mount the VFD close to the head so you can operate it easily. Since it will be close to the action...it makes the enclose more important ...so you don't get chips inside it.
Or you can mount the VFD in a remote location...then make a small control panel that can be mounted on the machine.
Anyway....there are many choices. And just about all of them will produce a very nice set-up.
A nice thing about the digital VFDs is that you can display the motor current on the LCD screen. You can compare this to the name plate rating on the motor...and this will let you know how hard you are loading the spindle.
Anyway, have fun with it!
Take care, Rob
