Submitted: December,  2003

On an unwind core, how much thread engagement should one have on the driving thread? Is it the same as a bolt of 1.5 times the diameter of the screw?

The minimum engagement you should ever use is
2 X the screw diameter.

In answering your question there is more to consider than just the thread engagement on the rotating core. Several other factors to consider are:

- The size of the thread used on the rotating core.
- The length of the thread.
- What type of support you have on the thread.