As a follow up to my previous thread about my newly aquired VMC-20 and the bad noise it's spindle was making, I did go ahead and shell out for a refurb spindle, as well as the parts to convert my machine from the crappy 6-belts system to the 2 belts pozi drive system. The stuff arrived today late morning:

Attachment 280376

Pretty much Engineering Christmas!

So, the real work started. I just got this machine so I am still in the process of cleaning it up. I spent most of the morning cleaning the sheet metal, etc. with degreaser. I do that on all my newly aquired machines. I got started really tearing things down at about 1:30 pm. I watched videos, and read instructions from whatever online vendors / fadal parts places that there are. they all give more or less the same instructions. Here's an image of the old spindle removed:

Attachment 280378

The only snag that I ran into, apart from how dirty this machine is, including many pieces of 6-belt style belt teeth, and shredded rubber everywhere, was that the spindle retainer, which is a split ring, needs to be unbolded at the split. This is not mentioned in the instructions, or videos from any of the fadal parts vendors. The screw is in the side of the ring, and until you remove it, you cannot split the retainer ring and remove it. The lip of the ring is underneath a thin flange on the spindle - so it doesnt just lift off. You have to loosen that screw in the side of the ring, then you have to pull the ring apart (i used a flat blade screw driver and a lot of finagling). Then you can bring it up and off of the spindle. At that point, all you have to do is put the spindle nose on some wood, then unbolt it at the bottom flange, and put the z-axis up to clear the spindle. Here's another view of the spindle, removed:

Attachment 280380

The spindle pulley indeed is removed using heat / two torches and some waiting around. That worked without any trouble what-so-ever. I could have swapped in the refurbed spindle right then, this was by about 5:30 pm (so it took me 4 hours, as a newbie, to remove the spindle). It's really not too bad of a job at all and I think anyone can do it, no problems.

Where I am into some bad territory is with this pozi drive upgrade. I need to replace the spindle pulley - fine, but I also need to replace the motor side belt pulley. OK... that's not so intuitive. The spindle side pulley is keyed to the motor shaft. This machine has a 5hp motor, which I believe weights somewhere in the neighborhood of 80 to 100 lbs. I do not have any kind of shop crane or hoist that can remove this motor for me. Furthermore, I don't want to pull the motor down from the machine. I don't even want to disconnect the wiring. Also, it's just me working on the machine, I don't have a second hand to help wrestle this damn motor perched on top of $15K worth of 'i dont wanna screw this sh*t up,' or hurt myself. So, if anyone has any suggestions about how to remove the motor from their fadal, I'd be happy to see another way than what I ended up doing. My way worked:

Attachment 280382

I ended up moving the z axis up pretty much to it's limit, then sliding a large board under the motor mounting plate. I had the back left motor mount pillar still attached / bolted into the rubber mount. I then unbolted that last remaining pillar and pulled that out and slid a 2x4 underneath the back of the motor mount plate so that the front was supported by a larger board laid flat, and the back supported by a 2x4 on its edge. I added a second large board in front of the motor to allow me to lay the motor down on the two front larger boards, with the wiring still attached and the cat track / cable manager un-strained. This worked, but was pretty perilous. I was able to handle the weight of the motor as the fulcrum was supported by the boards. I had the enclosure doors shut behind me so that if I fell backwards, they'd catch me. Now the motor is in a position where I can work on the pulley. I have ended here for the day, because now I need to think some things through about the position of the pulleys on the motor shaft, and on the spindle:

Attachment 280386

Has anyone gone through the 6-belts to pozi drive upgrade? is the spacing different between the two systems? the pulleys are different heights. I will do some CAD of it all to try and convince myself about where this new pozi-drive pulley needs to be on the the motor shaft as far as how far to put it on. On the spindle side, I could put the new pozi pulley on to the same height as the old 6-belts one, but is that the right thing? I have a VMC-4020 too which has the pozi system already, I guess I'll need to tare off the covers at least on that to try and make some measurements.

Also, I believe I can get the spindle side pulley off with a puller tool, but I am unsure of how to put the new one on. Maybe I can heat that piece too, but that seems like a weird thing to do with a keyed shaft and pulley? Has anyone ever done this pulley job on their spindle motor before? How did you remove the old one? How did you put the new one on? How did you know where to put it on the shaft / depth (especially if you were doing the 6-belts to pozi upgrade)?

Really this pozi-upgrade is a huge pain in the ass, and there are no instructions from anyone. You'll also find that different vendors include different parts for the kit! wtf! why? shouldn't a kit to accomplish this change-over be the same no matter what?


By the way, the old spindle bearings feel COMPLETELY bad compared to the new spindle, just turning it by hand you can tell a major difference. The old spindle actually catches in places like it has detents. I am excited to get this thing back together; i bet it will be butter smooth. Hopefully it will pay for itself soon there-after. Not a cheap set of parts to have to buy.