Possible problem.

[Swarf_Newbie]

(12-21-2019, 09:53 PM)Highpower Wrote:

(12-21-2019, 07:18 PM)Swarf_Newbie Wrote:  Now I would not think that 10mm silver steel 300mm long would flex that much under the pressure of a dti? but I could be wrong!   

Cheers.

Roy.

Actually a small diameter bar of that length will flex quite a bit under it's own weight when held at one end. What I was trying to ask is how are you adjusting the far end to have zero run out? Are you smacking the tail end of the bar to move it, or are you moving the chuck jaws to do it?  Moving chuck jaws.

Stan suggested checking your stock for straightness which is a good place to start. Just because a piece of stock is ground at a factory doesn't necessarily mean it will still be perfectly round and perfectly straight by the time it gets to your door. Fair enough, unluckily at this moment got nowt to check it on.( Dr Stan your post has been noted and filed! :-)  )

You might try drilling a 60° center into one end of your stock (up close to the chuck jaws). Then put the stock back in the lathe the way you have it now, but support the far end with a center in your tail stock. Zero the run out at the chuck end, and then check the run out at several places along the bar and see what you get.
Will do!

Thanks for the time and patience guys.

Cheers.

Roy.