Van Norman 7 1/2" dividing head chuck back plate info request

I recently acquired a 7 1/2" Van Norman dividing head that came with the dog for the spindle nose but no chuck. I have a suitable chuck and I need to make a proper back plate to mount on the dividing head. The dog has a clamp screw that squeezes the dog around the nose of the dividing head to keep it from unscrewing in use. Is there any similar feature on the chuck back plate to keep the chuck from unscrewing or does it simply thread on?

My VN dividing head just has a thread with a pilot behind it, and I made a chuck adapter for it as required, which screws on only. That said, I suppose it would be useful to have a locking feature on it. Two methods come to mind:

Cross-drill and tap a hole thru the side of the adapter into the thread, and use a set screw with a brass plug to bear against the thread (best if the plug has a partial thread profile to match the spindle’s.)
Or, cut the finished adapter through one side, drill and tap a cross bolt which will squeeze the adapter around the spindle thread. Then install the chuck.

If you want to borrow a thread gage for the spindle, I’ve got one, assuming our spindles are the same. I also made a spare aluminum blank adapter (with finished thread, pilot and back-face, but chuck mounting side is blank) that I might be willing to part with if you’re interested. Be back on line Sunday.

I did not incorporate any locking mechanism when I fitted a backplate/chuck to mine, and it has worked ok. I do make a point to consider the direction of cutting forces on any set up with the dividing head using the chuck.

Ferrous Antiquos said:

... I suppose it would be useful to have a locking feature on it. Two methods come to mind:
...

Click to expand...

Another thought is to rig up something that works with the dividing head's drawbar.

Cal

Here is what you should be thinking about, a back plate mounted on an arbor with a drawbar. Easy to make and you won’t need to worry about it slipping. Earl.

ANY SPAIR PARTS FOT THE V-N 7-1/2 D-HEAD?

thanks
DON H

I need the worm gear for mine, any one have one? I would like to buy one or at least get some details from one like the OD and any other measurements you can provide.

Thanks

Bill in Cincy

Mr_Bill, you will get better results if you keep the active discussion in one thread, instead of shotgunning messages across every old thread the search results throw up. This thread has been dead for six years.

I will say, thank you for adding some explanatory text. I wasn't sure if that giant bubble in the photo in the 2nd of your recent threads was pointing at the worm or the worm wheel. I will be adding a comment in that thread.