Author Topic: Rockwell Model #21-100 Vertical Milling Machine  (Read 3164 times)


Rockwell Model #21-100 Vertical Milling Machine
« on: July 19, 2018, 12:12:53 PM »
A while back I found a slightly used Rockwell model #21-100 milling machine, that was setting in the local ASME boiler repair shop, that I work with on a constant basis. They had move some equipment around and I saw it standing in a usually blocked off alcove. I asked about it and ended up buying it.

The mill originally was in a vocational training school, that sat there for 30+ years, basically unused, then sold of to the boiler shop, where it sat unused for another 10-15 years (?). So it ended up in my shop. The original 3 phase motor was damaged, but the rest of the mill was in excellent under the filth of many years of storage, even though it was mostly shrink wrapped. It took 2-3 afternoons, to clean up the mill to its present condition.

I started looking for a replacement motor, with very little success, because of it unusual flange mounting, the replacements were either very expensive or cheap, but requiring a complete motor shop visit to get the unit up and running. After further checking, I decided to make a “mill transmission”, to both alter and increase the number of spindle speeds, the concept was similar to the one I made for the Jet JVM-836 milling machine. I went from the 6 speeds, ranging from 370 - 6300 rpms, to a more useable 24 speeds, ranging from 90 to 6650 rpms.

The mill transmission required a relocation of the motor, so I made a bracket that adapts to the round column of the mill, originally I used a 1/2hp Dayton, 1725 rpm single phase motor wired for 240 vac operation, but was recently replaced by a 1 hp Smith & Jones (Harbor Freight), 1720 rpm single phase motor operation on 240 vac.

I picked up a new in a box Shars 4” mill vise, from a friend’s friend (bought, but never used), replaced the table and knee handles with some from Grizzly. I then made a 12” x 24” x 1/2” aluminum fixture table with 253 threaded holes (127 of them treaded for 1/2”-13 and 126 of them threaded for 3/8”16), that for the time being is still on the mill table.


Re: Rockwell Model #21-100 Vertical Milling Machine
« Reply #1 on: July 19, 2018, 12:16:51 PM »
A couple more pictures