Well, in the two years that it took for the correct drive to show up on ebay I got that injection molding press and used the 5kw motor and drive in there to replace the 2kw in the lathe. So that left me with the 3.5kw.
Now that I am out of work and have some time on my hands and no projects I need the mill for I figured I would give this project a try.
Last week I pulled the motor off the mill and took some measurements off the old motor and drew up a mounting plate that would allow me to mount the servo in the hole of the existing motor and allow it to swing to adjust belt tension. I sent the drawing off the IRC Aluminum in Portland for water jet cutting. Three days later I had the part in my hands. Only $110 for the cut with material. The aluminum alone (1/2" 6061) would have cost me at lead $60 shipped. Not bad. The part came out perfect, drilled and tapped the motor bolt holes and installed it on the motor.
Spindle motor mounting plate by macona, on Flickr
I decided to use HTD style belts to drive the spindle. The top speed of the motor is around 2500 RPM so and I want about 5k at the spindle. I had a 28 tooth, 8mm pitch, 50mm wide pulley so I bought a 56 tooth version off ebay NIB for $25 shipped. The SK bushing for the 35mm shaft on the motor I got from Applied Industrial for $30. The belt was about the same price but ended up having to get that from Motion industries. That should be here tomorrow. I had to bore out the bushing on the small pulley to fit the shaft on the spindle side of the vary-speed to 35mm. Technically it was too small but I got it to fit.
Spindle Servo Motor and Drive by macona, on Flickr
Last night I pulled the top of the head apart to get at the rest of it. Pulled out the top half of the pulley and the mechanism that adjusted it. While it was apart I found the top support bearing to be so-so and the bottom was dry. I could shake the bearings and they rattled around. I dug though my bearing collection and found NOS bearings to match the top and bottom. The bottom was an open style and the grease was dried so I cleaned that and put some new Kluber grease in it. Much smoother now! I reassembled everything and dropped the motor in place. Just need the belt now.
Spindle drive pulley by macona, on Flickr
Spindle servo installed by macona, on Flickr
Sunday I started on the wiring. Unwired the old motor and pulled out the old vfd. I had to move the internal 240-120m, 500va transformer so while I was at it I replaced it with a 750va one to give me a little extra aux 120v on the machine. I got the drive wired with its supporting contactors and terminal strips.
IMG_2067 by macona, on Flickr
Pretty much all finished now. Had a couple little bugs but they are worked out now.
Is that (gasp) a ratlle I hear?