School teachers couldn't see over old book shelfs cause they were to tall and they had to work to find out what students were doing down the rows, so I've shortened them so they can see what their students are up too
Step 1. Remove all books off the shelf's and then pull the shelf's them self's off
Step 2. disable the old shelves stands into separate pieces.
Step 3. mark out the height you want them to be
Step 4. Once all marked out use a band saw which will get a straight and clean cut, you can also place more then one on top of each other to reduce time.
Step 5. The beams you took off the bottom of the stands you will need to cut the ridges off half of them at both ends.
Step 6. With the other half of beams you didn't cut place them back into the bottom and lock them into place.
Step 7. Once you have completed all the other steps get a grinder with a flappy disc and take away a bit of paint only on the insides.
Step 8. When ready weld the beams you cut earlier and weld them to the top.
Step 9. Once all welded its up to you, you can grind the welds back to a flat and neat surface or you can leave it the way it is.
Step 10. When everything is done with the stands take them back to the library ready to place the shelves back on then the books and then you are DONE.