Why do I get a taper when turning?

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Originally Posted by irving2008

taking off a moderately fine cut, if I reverse direction the tool digs in and cuts deeper, yet I can't detect any significant movement in the slide itself.

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I like guessing games :dance:

It's a Vee bed, n'est ce pas? If so I'd look at the saddle bearing face opposite the Gibb strip. Has it worn into a bow? If so no amount of tightening the Gibb will stop the saddle twisting and you have some scraping to do.

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Originally Posted by Robin Hewitt

I like guessing games :dance:

It's a Vee bed, n'est ce pas? If so I'd look at the saddle bearing face opposite the Gibb strip. Has it worn into a bow? If so no amount of tightening the Gibb will stop the saddle twisting and you have some scraping to do.

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It is a vee-bed, the outer edges are angled at 60deg approx. The tailstock runs on the centre of the bed.

I haven't taken the saddle off yet. The gib strip is at the back so I assume that is where the wear will be, no? Is this a case of replacing the gib strip?

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Originally Posted by irving2008

I haven't taken the saddle off yet. The gib strip is at the back so I assume that is where the wear will be, no? Is this a case of replacing the gib strip?

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The Gibb strip can bend, it's the other side that may be the problem.

Suggest you loosen the Gibb, seize the saddle with both hands, shove it hard up against the Vee on the non-Gibb side of the bed and then twist it.

Does it rock or does it roll? You should be able to feel if the contact face has bowed.

nnnnnnnnnn

onecut, check your PM, you have mail!

Tickling the swarfe off a bar usually ends up with some weird results, including tapers and poor finishes. Most people seem to be scared to use the correct speeds and feeds, particularly when using carbide tips because you have to give it some welly and take deep cuts, often 2 or 3 full turns of the handle at a time!