DKForge Posted November 6, 2013 Share Posted November 6, 2013 Ok so basic strap hinge mechanics question. I am making strap hinges which attach to the door via a plate and pin. Is the pin meant to rotate freely in the barrels on the plate as well as the barrel on the strap or is it better to have the pin snug in the plate barrels and just have the strap rotate on the pin? I know with a pintle attachment the strap just rotates on the "pin" so it got me thinking about the how a hinge actually works. Thanks in advance for any advice. Quote Link to comment Share on other sites More sharing options...
Jim Coke Posted November 6, 2013 Share Posted November 6, 2013 Greetings DK, It just does not matter.. A little lubrication and it will find its own way.. Most of the wear on a hinge is on the web part that takes the weight.. On the bottom.. I guess if your hinge has three lugs on one end and two on the other it would be technically proper to lock the pin to the 2 lugs for more surface area support and wear factor.. As with all machines I always ask myself WHERE WILL BE THE WEAR.. I hope this helps.. Forge on and make beautiful things Jim Quote Link to comment Share on other sites More sharing options...
metalmangeler Posted November 6, 2013 Share Posted November 6, 2013 I lock mine up on the plate side as I think if the pin rotates it may bind like a tong rivet. Now you have 2 oppinions.:) Quote Link to comment Share on other sites More sharing options...
Quarry Dog Posted November 6, 2013 Share Posted November 6, 2013 Whatever you do, make sure you can oil it. I've seen more hinges seize up and break off of heavy shipping container doors because you couldn't get oil into them. I imagine this carries over to other heavy hinges. Quote Link to comment Share on other sites More sharing options...
SmoothBore Posted November 6, 2013 Share Posted November 6, 2013 By leaving the pin free, you double the "play" in the hinge. I find this unnecessarry, ... and therefore unacceptable. . Quote Link to comment Share on other sites More sharing options...
ThorsHammer82 Posted November 6, 2013 Share Posted November 6, 2013 count one more for locking it in. leaving it to move adds additional wear when it's not needed. Quote Link to comment Share on other sites More sharing options...
petere76 Posted November 7, 2013 Share Posted November 7, 2013 Dk, The weight of the door is transmitted to the web of the leaf and onto the corresponding barrel of the stationary mate. The weight is an up and down force. The pin really only aligns the two parts because there is little radial force involved. Think of the stationary side as the pintle, it carries the weight. Don't rivet the pin tight , keep it loose and put some oil to it, and it should work fine. Peter Quote Link to comment Share on other sites More sharing options...
DKForge Posted November 7, 2013 Author Share Posted November 7, 2013 Thanks for all of the responses to my question. Hinges will be complete by this weekend. Quote Link to comment Share on other sites More sharing options...
DSW Posted November 7, 2013 Share Posted November 7, 2013 The weight of the door is transmitted to the web of the leaf and onto the corresponding barrel of the stationary mate. The weight is an up and down force. The pin really only aligns the two parts because there is little radial force involved. I'm not 100% sure I agree with that statement. Weight applied at a distance on a cantilevered support is referred to as a Moment force in engineering and includes both a vertical load as well as a rotational load. Granted on a long door with two hinges ( or more) that rotational load is decreased by the distance between the two hinges as it acts like a diagonal support to absorb some of that rotational force. If you have ever pulled the pins on a door with sloppy hinges you know it won't just sit there on it's own, but will immediately begin to tip as soon as you pop the 1st pin. There is some side force being applied to the pins because the door wants to rotate. The wider the "door", the more weight is applied at a distance and thus the more force the pins will have to take, especially if the distance between hinges is short, like on a large driveway gate. Quote Link to comment Share on other sites More sharing options...
Chinobi Posted November 8, 2013 Share Posted November 8, 2013 DSW is correct, the pin is actually resisting shear forces generated by the moment from the door's weight being supported out of line from its center of gravity. Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted November 8, 2013 Share Posted November 8, 2013 DSW and Chinobi nailed it. The reason there are multiple barrels in a typical door hinge is to multiply the shear planes on the pin. Each plane takes it's proportion of the shear load which reduces the maximum shear the pin will be subjected to at any point. Quote Link to comment Share on other sites More sharing options...
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