Here is a little light entertainment. In case anyone is getting bored.
Assume you have just acquired an old lathe. It comes with a face plate and a four jaw chuck.
But there are a couple of snags.
There is no back plate for the chuck.
But more importantly, the faceplate register won't fit the register on the lathe mandrel. It is too small.
On the positive side, the thread on the plate fits the mandrel thread.
So, how would you begin to fit your faceplate to the mandrel, bearing in mind that the future accuracy of the whole lathe depends upon the register fit.
Dave.