how to convert a offset sheed feed press to pack to pack continuos offset press?

Answer 1

sheet fed presses, in general, are much more complicated then roll fed because of the need to:

1. separate the sheets
2. grip a single sheet
3. pull the sheet through the printer
4. stack the sheet neatly at the other end.

A press designed to be web (another way to say roll) fed
is a much simpler design, and generally wastes more paper.

1. the area where the plates are clamped into the drum can't be printed. in a sheet fed press, the feed is arranged so there is no paper under the blanket when the non printable section passes. Stopping and starting the paper to avoid this waste would be impractical.

2. since there is no "edge" for grippers to grab, the paper is transported by pressing rollers along (usually Both) sides of the paper.

You will see these effects if you look at a modern newspaper. Big margins all the way around, and embossing along some of the edges where the paper transport rollers squeezed it.

This does not mean you can't do it. With the number of publishers being put out of business it might be cheaper to buy a web fed offset press than it would be to try and convert a sheet fed.

The big advantage of a web fed press is that it can go much faster, but a converted sheet fed press might not be able to work at higher speeds due to unexpected effects like ink being thrown off faster running rollers, etc.