Hello Jack,
I'm not sure which way you are getting an error or whether it is consistent. Consistency is very significant as it can be a very good clue as to where the problem lies.

Have you clocked the table &/or vice from the ram? That is what is doing the cutting so should be your reference. If the table slides are loose or worn, the table will tend to droop, using an outboard support may then lead to indeterminate results.

I am assuming, you have the jaws of the vice parallel to the ram so that they open and close perpendicular to the ram and the problem is that a job ends up tapered from end to end. You say 005, but over what length? The base of the vice between the jaws is only probably 3" wide so if your 005 taper is over, say 8", that's less then a thou per side across the width of the vice. It's not too hard to get that much from dirt, surface damage, and even bounce when knocking the work down as well as any slackness in the vice motion which will tend to lift the moving jaw upwards as you clamp it up.

If you could give a bit more detail about the geometry it might help define the source of the problem more definitively.

Rgds
Richard

Richard/Bob
The workpieces in question are quite small.no more than 4" long and 3" wide.It was turned over end for end.The vise jaws are parallel to the axis of the ram.
I did use a DTI, fixed to the ram, in order to get my vise true. However I didn't pay particular attention to the fact that the ram ways could be worn, just never thought of it at the time.As you might have guessed, I'm new to using shapers. I think the problem may possibly be with the vise, as, although it's quite large, it is only a lightweight affair. I will re-check the truth of the vise, and  as suggested look for wear on the ram.
Thank you for your help.
Jack

Richard,
I can't honestly answer your questions. I think I will have to go back and do some more tests. I will take more care this time to see exactly what is happening.
Thank you
Jack