# Determining pivoting hinge location?

 Forum topic by lateralus819 posted 11-29-2014 11:28 PM 1069 views 0 times favorited 8 replies
 lateralus8192241 posts in 1885 days 11-29-2014 11:28 PM Not really sure what this type of hinge is called, but i saw this box online and thought it would be neat to add my own flair and build it as a surprise for my wife as a jewelry box. Would there be a formula for determining the placement? I know i could make some templates from 1/4” luan and mess with it until i found it. Was just curious if there is an actual mathematical formula?

## 8 replies so far

 Bob Kassmeyer223 posts in 2921 days #1 posted 11-30-2014 02:04 AM I don’t know but would like to. -- Bob Kassmeyer, Nebraska Scott Smith6 posts in 3131 days #2 posted 11-30-2014 03:24 AM If you made all 8 links the same length and placed the holes in the base and trays the same distance apart, the tray would stay parallel to the box through their travel. The hole-to-hole distance for each link would be L=sqrt(x^2 + y^2), where x is the horizontal distance when closed between holes and y is the vertical distance. Making the links longer will give a larger space when open, but more stress. The opening (per side) would be 2*x (same x as above). Let me know if sketching it all out would help. Scott -- Scott, Toledo, OH lateralus8192241 posts in 1885 days #3 posted 11-30-2014 03:41 AM Scott a drawing per se would be excellent! Long time out of mathematics lol. Yonak986 posts in 1517 days #4 posted 11-30-2014 03:45 AM I agree with Scott. To make it maybe a little more visual. Notice that the hinge points, when closed, are lined up on the centers of the upper trays and the outer hinge points are equidistant from the ends (and from the centers, as Scott notes). The closer you get to the ends, the more of the bottom tray will be exposed when open but, as Scott says, the more unstable it will be. I would experiment with blocks, sticks and nails in slightly oversized holes. Mark the hinge locations with the assembly in the closed position. lateralus8192241 posts in 1885 days #5 posted 11-30-2014 04:00 AM Thats what i was thinking Yonak. Just make some “hinges” of the size I’d like, and since (i assume ) the holes don’t matter on the hinges themselves, morose on the boxes, just use some tacs to find the right placement. I was toying with the idea of trying to make the mechanism invisible, not sure how possible that would be. ElChe630 posts in 1332 days #6 posted 11-30-2014 05:30 AM Math scares me. Sketches don’t. -- Tom - Measure twice cut once. Then measure again. Curse. Fudge. Yonak986 posts in 1517 days #7 posted 11-30-2014 08:24 PM I was toying with the idea of trying to make the mechanism invisible, not sure how possible that would be. - lateralus819 The only way I can think of to make the mechanism invisible is to cut slots in the bottoms of the trays, which would create more issues .. not insurmountable. lateralus8192241 posts in 1885 days #8 posted 11-30-2014 10:37 PM Yah thats what i was thinking Yonak. Just use a pin on the end of the large single draw, with a magnet next to it, so when the sliding drawers reach a max distance it holds it.