On 6/16/2013 1:09 PM, woodchucker wrote:


Not sure I understand that. Piano hinges have been used to hold heavy
tool doors on work cabinets for a long time. I would think they actually
reduce sag since there are more points of contact. While not as robust
as a regular door hinge you would not be able to fit a door hin in this
instance. So I'm not so sure I think they lead to sag..
I think it depends on what the load is, and how it's used. I think
having a slight rebate for the hinge helps avoid issues.



OK, a picture is worth a thousand words.

http://www.flickr.com/photos/lcb11211/9061338634/

If you will notice, the brand new piano hinge pictured, has gaps between
the "ears" on each side of the hinge. Because of this gap the "ears"
that are actually supporting all of the weight are going to wear more
quickly and or the ones carrying the weight will distort until some of
the other ears begin to engage and help carry the load. The the gap
closes, the door settles/sags.

When used in a horizontal position the ill fitting halves do not matter
because most of the load is then placed on the hinge pin vs. the ear
tops and bottoms when used vertically.