digga Posted January 19, 2013 Share Posted January 19, 2013 hi i was after some help. i have to put up a lot of gates ( both metal & wooden ) and sometimes come up against the age old problem of gates having to rise up a slope as they open but be close to the ground when shut i know how to achieve this by offseting the bottome hinge. \what im after the help with is how to calculate the offset was thinking of maybe doing something on excel to calculate for different width gates and amount of rise needed i done a bit of a search before posting and come across the self rising gate hinge thread . where i see a reply from john b said Distance to offset centres of the hinge pins can be calculated by measuring the vertical distance between the hinge points and multiplying this size by the rise required, the result being divided by the length of the gate so wanting to check i have this right before messing up anything expensive i measure the verticle distance between the pins ( must confess been hanging gates for a while and didnt think this measument would make much difference but here to learn ) then mutiply that by the rise needed and divide that by lengh of gate is this including the eyes on the gate so you measure it from the centre so you have the mark for your pin location on the post ? many thanks david Quote Link to comment Share on other sites More sharing options...
bigfootnampa Posted January 19, 2013 Share Posted January 19, 2013 Basically this is a simple right triangle problem. By bringing the top pivot for the gate downhill or moving the bottom pivot uphill (or a combination of the two) you create a line perpendicular to the slope when the gate is opened. If you lay this out on paper so that a triangle proportional to your gates dimensions has the bottom parallel to the slope the offset from vertical between the pivot points will be the needed offset to make the proper rise in the gates swing. If you move the pivots closer together vertically, less offset will be needed to make the proper slope in the swing. I hope this helps you to "see" what John is describing mathematically. Quote Link to comment Share on other sites More sharing options...
digga Posted January 19, 2013 Author Share Posted January 19, 2013 thank you for taking the time to reply its coming a bit clearer now as i said here to learn and theres such a lot of valuable knowledge here wanted to ask a few questions even though some may seem stupid and get it right. before messing up and still might see if i can do something on excel to calculate offset for those gates where the verticle positions of pivot is allready fixed on pre supplied gates Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted January 19, 2013 Share Posted January 19, 2013 I would think Exel a bit of overkill, but that's me. It's just a proportion The width of the gate (W) is to the Rise in the gate ® as the spread of the hinges - center to center (S) is to the offset (O). As Bigfoot says, you need the line between hinges perpendicular to the ground. R/W = O/S or O = R*S/W.' Quote Link to comment Share on other sites More sharing options...
pkrankow Posted January 19, 2013 Share Posted January 19, 2013 Draw a picture, keep it simple. Everything is similar triangles. The offset of the hinge creates a triangle that has the same angles as the rise of the gate. The rise of the gate is an imaginary triangle underneath the gate panel.Phil Quote Link to comment Share on other sites More sharing options...
doc Posted January 19, 2013 Share Posted January 19, 2013 The only issue is that the full rise of the gate only occurs at a 90* opening of the gate. At any point between this position on either side of 90 it is less. That is why offsetting hinges can be used to make a self closing gate or door, or one that will also stay open if moved past 90 degrees from the closed position. Quote Link to comment Share on other sites More sharing options...
digga Posted January 20, 2013 Author Share Posted January 20, 2013 thanks everyone for the help Quote Link to comment Share on other sites More sharing options...
John B Posted January 21, 2013 Share Posted January 21, 2013 Seems that is sorted for you then. All points seem to have been covered. Great to see somebody using references already been covered without just asking. Well done and Thank you. Quote Link to comment Share on other sites More sharing options...
digga Posted January 22, 2013 Author Share Posted January 22, 2013 yes thanks again for everyones help Quote Link to comment Share on other sites More sharing options...
LEW PARKER Posted September 30, 2022 Share Posted September 30, 2022 I built an offset hinge point for our driveway’s double gate. The gates opens inward. Facing toward the street, the bottom of the right hand gate must rise to clear an upslope in the driveway. Next to the right hand gate post, I installed another post to hold the bottom hinge J-bolt. This takes a lot of the strain off of an angled hinge that otherwise would be attached to the main post. The bottom right of the gate holds the tube that hold the J-bolt pivot. That tube is welded to the threaded shaft of another J-bolt, with the J cut off. That shaft is attached to the bottom right of the gate, in a threaded tube welded to the gate at a right angle. With the extra lengths of threaded shafts, I was able to adjust the gate to parallel the ground when closed, and adjust the necessary rise to clear the slope when open. This sounds complicated without an image. I’ll try to post a photo. (Nope, didn’t work.) Quote Link to comment Share on other sites More sharing options...
TWISTEDWILLOW Posted October 5, 2022 Share Posted October 5, 2022 Howdy from eastern Oklahoma and welcome to the forum LEW! there’s a button at the bottom of your post that allows you to add photos, where bouts you from? What kinda smithin you do? Quote Link to comment Share on other sites More sharing options...
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