Thread: Leadscrew not centered.

Ideally no. Schlesinger and others have limits on leadscrew alignment with the bed and the number is around 0.1mm. However, that number is an acceptability criteria for new (toolroom grade) equipment, which you may or may not fall into.
Assuming that your bed is not horribly worn you may have enough play in the mounting holes for the leadscrew to be able to loosen things off and realign.

Michael

The Leadscrew is long and thin,there would be a very good chance that due to its length and the position of the carriage that the amount of movement you are seeing/getting will be normal for the type of lathe you have.It should not cause any concern,wind the carriage all the way towards the Tailstock and apply a small amount of pressure by hand to the Leadscrew in a Vertical direction,you should see the same amount of movement if not more than when you engaged the Halfnuts with the carriage 70% of the way along the bed.Most if not all of the larger/longer lathes will have either 1 or 2 Leadscrew supports along the bed to compensate for sag in the Leadscrew.
I would not be worrying about this slight movement as it shouldnt have any detremental effect on the performance of the Lathe.

The main reason for asking is that when taking off the carriage, had noticed that the bolts on the block for the leadscrew- feed-power bars were bent, the carriage also gets tighter when winding to the tailstock end,
the lead screw-feed has a tight spot when turning it by hand.
when the block had been taken off, the tight spot of the carriage disappears.

Michael,
was unsure if it was o.k. to adjust the block as it's been like this since new, have not cut many threads and never used it anywhere near the tailstock end.
removed the block alignment pins and replaced the bolts, need to machine the bolt heads slightly for proper alignment.
it made a difference as there are no more tight spots on the carriage and lead screw.