True running mandrel

[Tiger]

I want to make a bottle stopper mandrel as per the instructions (limited) on this site hot to make a bottle stoppers, wine bottle stoppers, bottle stoppers, stainless steel, wood stoppers, glass bottle stoppers, blown glass, fused glass (http://www.torne-lignum.com/make_stoppers.html) (about 3/4 of the way through).

Trouble is no matter how accurate I drill the hole for the screw the end-result is a mandrel that does not quite run true. What can I do to make the mandrel run true?

[sjm]

Are you using a center drill to start your hole? Pretty much essential for accurate end-grain work.

[wood hacker]

Tiger

Ther was a recent article in one of the turning mags that described making your own screw chuck very similar to what you are trying to do. The suggestion in the article was once the coach bolt was glued in place to reverse the chuck / mandrel and grip it by the coach bolt. You then clean up the spigot on the chuck such that it runs true to the coach bolt.

cheers
WH

[Skew ChiDAMN!!]

Another option is to:

drill the hole slightly oversize
place the screw in a jacob's chuck in the tailstock to hold it square
fill the hole with epoxy glue (while still in the chuck)
wind in the tailstock to insert the screw.


Only as accurate as your tailstock alignment, of course!

[Tiger]

Thanks guys. The centres are very slightly out in a vertical orientation so can't trust the lathe to drill perfectly centred hole. Tried your solution WH, got very close and that will do for my purposes so thanks a lot.