Today I decided to make a tailstock threading adaptor for my mini-lathe as an aid for producing threaded spraybars (brass) for model engines.
Apart from the fact that I spent an hour or two grinding a boring tool from a 1/4" HSS blank (after trying the supplied and also binning the supplied chattering brazed insert rubbish) it was a pleasure to make a clean hole that fitted my circular split dies.
Add one more hour for reading up the great article by George H. Thomas (M.E. 3 June 1977) on Boring Tools.
I have a few questions:
1. How tight should one fit the split die into the adaptor body (does it need room to expand a bit and will the die run off-center if the hole is too big)?
2. What are the advantages/disadvantages of fitting a spring between the die-holder body and the chucking device? (I can see how it might apply positive pressure to the die, but then how much is too much)?
Dies are B.A. (of good Aussie quality ), 7/8" body dia with two locating pips and an expander slot, lathe chuck rotation is by manual labour.
* Danny M *