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What kind of hinges are these?

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9K views 32 replies 12 participants last post by  jacww 
#1 · (Edited by Moderator)
I've searched all over for this type of hinge. They are the same sort of hinge you find on old folding rules. I can't find them anywhere, and I don't even know for sure what they are called.

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Thanks for any help.
 

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#4 ·
Scissor hinge - rockler has em.

M

- Madmark2
No, Rockler does not have them. They have knife hinges, but that's not exactly the same thing. I had already looked at the usual places on line - Rockler, Garrett Wade, Lee Valley, no luck. Even the images that web searches returned never showed a hinge, always a folding rule with the hinge.

I'll probably just buy a folding rule and take the hinge from it.
 
#9 ·
You need the hinge to build a sector correct? I am looking for the same thing you are, and I am having trouble as well. You might have better luck searching for a "Pivot" or "Pivot Hinge". Using those keywords, I have come very close to finding what I need, but have not hit the jackpot yet. I'm not giving up, and if I find the right pivot I will post the source here 4 U.

Also, as you may know, you can use a folding ruler as a sector. I do it all the time and it works quite well. The problem is you don't have all three lines (line of lines, line of polygons, and line of circles) that are on a "real" sector. But, as woodworkers, we most commonly use a sector for finding proportions without using a measuring tape and doing the math (nice!). That can be done just using the "line of lines", or more simply put, just using marks on the edge of the sector.

Good Luck!
Bill
 
#12 ·
Since Rich was originally looking for these in April of 2017, I'm going to go out on a limb here and say he has either already found them or has stopped trying…Rich?
 
#13 ·
Well, the hinge that is in the bottom picture of the original post was designed and manufactured by the same guy who built the sector it is in. I can't remember his name, but he teaches a class on building sectors. Bottom line is there is no commercial source for that hinge.

The idea of scavenging a pivot hinge from an old folding ruler may be doable, but I don't think it is a practical solution. the part of the hinge that gets embedded into the wood is quite thin, and I don't know how you would accurately cut groves for them in the new project.

I just finished a prototype of a simple sector that is working very well for me. I just used a 10 X 32 machine screw at the "pin" so the two wooden legs of the sector pivot around it. I put a knurled nut on the top of the screw so I can tighten it as required.
 
#14 ·
Tung's right. This is an old thread and I've found a hinge that works. For the record, the designer of the sector shown above is Brendan Gafney. I corresponded with him regarding obtaining a hinge, but he had only made enough for that run of sectors that sold out.

Scavenging an old hinge is very doable. Not all folding rules have the same style of hinge. Among Stanleys for instance, there are round, square and arched. They all connect to the legs in a different fashion and some are more suitable for repurposing than others. Not to take anything away from Brendan's fine work, but the round hinge is the weakest and was only used on low-end rules back in the day.

Also, proper use of a sector does not require locking the legs with a nut. All transfers are done to and from the sector with dividers. You never place the sector itself against the workpiece. I know articles have been written that show that technique, but they are dumbed-down to make them more approachable to someone just wanting to use a couple of sticks as a rough approximation. That will get you most of the way there but is very inaccurate.
 
#15 · (Edited by Moderator)
I took Brendan's sector making class at Lost Art Press this year. It was great a great class and all six of us made beautiful sectors.

By his own admission, Brendan sacrificed many old rules to understand the hinge. He designed the sector hinge and found a machinist with a water jet to cut the pieces. The hinge was actually 5 pieces of brass (not counting the 5 pins). There are 2 disks and 3 shaped pieces that are inserted into the wood arms. Once the pieces were inserted into slots in the wood and the 4 pins inserted to hold them, the pivot pin was inserted and peened. The holes in the top and bottom disks were slightly "countersunk drilled" to provide space for the peen to hold everything in place.

TonyC

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#16 ·
Brendan is holding another class in Sept. of 2019. I would love to go, but not sure I can given it is 1,700 miles North West of me. That adds a lot to the cost of the class. So, I have opted to work with a simpler version that only has the "line of lines" on it. The prototype I made works quite well but, there is one thing I don't like about it. The line is just the inside edge of the sector with marks like a ruler to show the increments.

@Tony Could you describe the method used to mark the line of lines on your sector? I assume the angle is somewhat arbitrary as long as each line is exactly the same angle from the center of the hinge. I would like to figure that out before making another sector.

Bill
 
#17 ·
@Tony Could you describe the method used to mark the line of lines on your sector? I assume the angle is somewhat arbitrary as long as each line is exactly the same angle from the center of the hinge. I would like to figure that out before making another sector.

- Willyd57
That's not Tony's sector, it's one of the ones Brendan made. You're right that the angles of the lines are arbitrary but must be equal on each leg, and the points must be equally spaced as well. What you can't see very well in the photo is that the points have very small brass tubes inserted to allow the points of the dividers to register precisely and also to prevent them from getting worn.

The other thing that's critical is that they align perfectly with the center of the pivot point on the hinge.
 
#18 ·
Bill,

The pictures in my post are of the sector I made in class.

The one precision part of making the sector was drawing the 3 lines on the scales. They MUST go through the center of the pivot point of the hinge. We used a straight edge laid so it is on the center point of the hinge. The line was marked using a dull awl held at an angle so it simply makes a dent in the wood NOT a scratch. Then without moving the straight edge, we used colored pens to mark the line.

Yes, the lines need to be the same angle on both sides. Unfortunately, I cannot remember exactly how I marked the end points of the lines so they are at the same angle.

For the class Brendan eliminated the use of the tiny brass tubes at the points along the lines. It would have been too time consuming.

I hope this helps.

TonyC
 
#19 ·
Sorry for the confusion. I didn't know he taught classes where the students made one. I have to say though, leaving off the brass tubes seems like a major mistake. It wasn't that hard to put them in.

The biggest issue cannibalizing old rules for the hinge for me was getting one in good shape without destroying a vintage rule. Like I said, only certain hinge styles lend themselves to being repurposed for something like a sector. The rules aren't manufactured anymore, so an older rule is the only option I found, and I have a problem with the idea of ruining a vintage tool that's still usable. As it turned out, I won an auction with four unused Stanley No. 63 folding rules for $10. As luck would have it, one of them had a slightly warped leg - warped enough to make the rule defective and unsellable - so I was able to use that one with a clear conscience.

Anyway, my hinge question was solved over 18 months ago.
 
#21 ·
Thanks everyone for all the great feedback. I'm beginning to feel more confident about building my next sector. I believe I could make my own hinge from brass, but I think I will stick to using a machine screw. It does not look as nice but it works just fine. I definitely agree that destroying a vintage too to get a hinge is not good.

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Also, adding the small brass tubes is a great idea, I think I will do that. As for drawing out the Line of polygons, and the line of circles, I am not sure how to do that. I have a paper sector that was made by George Walker who co-authored the book By Hand And Eye, which discusses how to use a sector. I could use that as a template, but I would rather lay the lines out knowing what I am doing!
 

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#23 ·
Before I did any drilling, I used an awl to mark the spot where I was going to drill the hole for the screw. Then, I set a pair of dividers to the distance I wanted for each increment and walked the dividers down one leg of the sector making prick marks as I went. Then I clamped the two halves of the sector together, and drilled a hole exactly the same diameter as the screw. On the bottom of the sector I countersunk the hole so the whole assembly would lay flat on a bench top. Then I went back and made the horizontal marks where each prick mark was made and added the numbers.

There is a drawback to using this set up as a hinge. The hole will enlarge over time because as the screw wears away at it. That is a strong argument for going through the trouble of making a brass pivot hinge. Possibly, Brendan will make more hinges than he needs for his next class in Sep 2019 and sell a few off.

Bill
 
#24 · (Edited by Moderator)
That's a nice design, Bill. Far better than my first try at one. You could reduce the wear from the screw by inserting a sleeve.

I had an opportunity to buy one of the sectors Brendan made on the By Hand & Eye site when it first came out. I got an email from them, went and looked and…. they were selling for around $300. Maybe it was $285, I don't recall precisely. What I do recall was that it was several times what I'd have been willing to pay for that sector.

My dream is to get my hands on a true vintage piece. Maybe made of ivory and silver. If that ever popped up, then I'd be willing pay several hundred to get one.
 
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