- Joined
- Jun 17, 2011
- Messages
- 2,062
Okay, you asked for it. I made up this little dividing head / rotary table for my mini-mill. I know I said I'd take it apart to photograph it, but I seem to recall that I trued up each stage as I mounted it on the hub. I don't want to risk throwing out the setup by taking it apart.
Ignore the tilt table and start with the long base plate bolted to the table. Next up is a bushing plate with a hole closely sized to fit the hub. The main feature is a 36- tooth sprocket mounted on a hub held down by a center bolt recessed into the base plate. The two towers at the ends have steps milled in for a rub fit to the underside of the sprocket.
The tops of the towers are grooved for an easy slide fit on the two index blocks. The thinned down area at the tip of the block is to allow it to clamp the sprocket to the step on the tower while still fitting under a faceplate which can be bolted to the top of the sprocket. The holes around the hub and the raised portion are sized to hold chucks and plates used on the standard HF style of mini-mill.
The key to indexing twice as many angles as the sprocket has teeth is seen on the underside of the index blocks. The slot in the tip brackets a sprocket tooth (giving angles on the ten* points) while the angled outside faces wedge into the space between teeth (giving the 5* spaces).
The table turns easily by hand when the two index blocks are pulled back. When it reaches the right location, the blocks are slid forward and the setscrews tightened to lock the table in place for drilling or milling.
Actual details are up to the individual builder. The concept of using an inexpensive, readily available sprocket (or gear) as an indexing source is the main point of this post.
Ignore the tilt table and start with the long base plate bolted to the table. Next up is a bushing plate with a hole closely sized to fit the hub. The main feature is a 36- tooth sprocket mounted on a hub held down by a center bolt recessed into the base plate. The two towers at the ends have steps milled in for a rub fit to the underside of the sprocket.
The tops of the towers are grooved for an easy slide fit on the two index blocks. The thinned down area at the tip of the block is to allow it to clamp the sprocket to the step on the tower while still fitting under a faceplate which can be bolted to the top of the sprocket. The holes around the hub and the raised portion are sized to hold chucks and plates used on the standard HF style of mini-mill.
The key to indexing twice as many angles as the sprocket has teeth is seen on the underside of the index blocks. The slot in the tip brackets a sprocket tooth (giving angles on the ten* points) while the angled outside faces wedge into the space between teeth (giving the 5* spaces).
The table turns easily by hand when the two index blocks are pulled back. When it reaches the right location, the blocks are slid forward and the setscrews tightened to lock the table in place for drilling or milling.
Actual details are up to the individual builder. The concept of using an inexpensive, readily available sprocket (or gear) as an indexing source is the main point of this post.
Last edited by a moderator: