A little over 2 years ago I purchased this dividing head from an OWWM member. He said it was missing a few pieces and jammed up but the price was good. Finally, I’ve gotten around to working on it. The dividing head has no brand on it but there is a patent stamped into the head. According to the patent records online (from 1890!), this dividing head was made by Cincinnati. While going through the dividing head, I found 47X stamped into multiple pieces. The patents indicate this dividing head was used on a horizontal milling machine. It has a “drive shaft” allowing it to be driven by the milling machine.
If you’re not familiar with a dividing head, it’s a device for dividing a circle into numerous pieces. It does this precisely by gear reduction and an index plate. This one can do between 2 and 2640 divisions of a circle but probably not every integer in that range. More on this in a future post.
This is what I started with. There’s a three jaw chuck, large locking “nut”, curved cover in the box, and bag of small parts.
With the plate out the screws can be removed that hold the “drive shaft” housing. The wood dowel helped me to move the spindle block without damaging anything. The dividing head has two bolts with a T shaped head to lock the spindle block in position. They can be removed by orienting the hole in the spindle block to remove them. To remove the spindle first required removing the worm gear. The first step in this is to remove the brass “nut” on the worm gear shaft. It wasn’t tight and I found the best tool I had to remove it was a pair of bent needle nose pliers. Once the “nut” was removed, a spacer, and the part I’m going to call a thrust bushing can be removed. The bushing just sits on the shaft but it took be a little bit to figure out a way to grip it to pull it out using some large retaining ring pliers (not the adjustable wrench in the pic).
At this point I had access to the worm gear and the shaft it is on. This took me the longest time to get out. Eventually, I realized I could thread a regular hex nut on the end of the shaft that I could pull on with my fingers. While doing this, I turned the spindle (using the gear and shaft that the arm with plunger would normally turn) so that the force on the worm gear would help push it out. Finally, it came out. There are some spacers that go on the smaller end of the spindle. I thought they were threaded in initially but it turned out they just slip over the spindle. I oiled them and was able to get them removed with a magnet. There’s also a big round piece that screws in to hold the spindle in place. It was already removed when I got the dividing head but, for anyone else, it has to be removed to get to the spacers. This circular piece holds in a couple parts that lock the spindle in place. The piece was held in place by a pin on the back side of it. To remove it, I slowly worked it loose going around the outside with some scrapers. With the worm gear removed, the spindle is able to be removed in the direction of the smaller end. In the picture, the spindle brake piece is shown on top of the spindle.
To get the shaft out this casting I needed to first remove the bevel gear which required moving a taper pin. This pin was stuck in and I tried driving it out with a hammer. I was afraid I might damage the casting if I kept it up and instead chose to drill it out.