I am a real fan of the VFD (variable frequency drive) route of speed control. 99.9% of the people will not maintenance a DC motor correctly, if at all. Leading to motor or control failure. 3 phase induction run motors used as most of us will are life time maintenance free. Don't try and lube them, you don't know how, again the 99.9% factor.
The vfd offers speed control yes, but also offers so many more things in the same package. Voltage spike/dip protection, phase failure protection, easy direction changing, ramp up/down to speed, preset speeds, low rpm torque control, skip frequency for vibration problems, 1 phase to 3 phase conversion without open phase operation such as phase converters, overload protection, low frequency protection (cooling problems), braking solutions and stuff way over my head. Motor amperage or rpm or signal input/output is usually a display on the front of the unit.
There are a few do's and don'ts as with all things and they must be sized properly. Also the demand for constant or variable torque application is important so just any one off ebay may not necessarily work. Coming from the electrical field I have installed litterly hundreds of them from quite a few brands and have my likes and dislikes from experience. We seem to have quite a few knifemakers in this area and these drives are real popular on their belt grinders and they need to reverse them for some polishing step they do. They are generally all pretty much bullet proof for installation from dumb electricians so just be sure to obtain a good current instruction manual as they all program differently. They usually program in block fashion so even a machinist can do it!!!!!!!! Little try at creative humor.
I love piddling with them so if I could be of help, I would be glad to try. If you wish PM me and I will give you a list of what to look for so your first experience is a happy one.
