# PVC pipe hinge feedback



## Buzz (Aug 26, 2011)

One of my current monster projects requires that the arms have a linear hinge. So I'm trying to find a way to hinge my PVC pipe so that in the relaxed position the arm has a 90 degree bend. Then when actuated the arm straightens. After some serious skull scratching I've come up with this...

The 3/4"x10" PVC pipe will inserted into a pine 2x2x4" with a 3/4" hole drilled down the center. A couple holes for anchors and a bit of Gorilla Glue should hold it.









Then I just use a small hinge to attach 2 of these together.









The 2x2 look kinda long in the picture but in reality, the 2x2 lengths will be about 4". They are only needed to hold the pipe and attach the hinges.
Does this sound good? Anybody try this before?


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## Victor (Sep 4, 2011)

I could see that for knees and elbows. What motion are you trying to achieve? I use three loop made from wire or zip ties for my joints. Shaved down T sections would allow you to keep from drilling holes into your PVC. Nice pics BTW.


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## corey872 (Jan 10, 2010)

I suppose that would work. 3/4" Sch 40 PVC is actually 1.050" OD. You might be able to find a 1-1/16" spade or auger bit which would give 1.062 and be pretty close. Is the PVC pipe giving you something that just a straight length of wood is not?


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## ouizul1 (May 22, 2010)

1-1/16" bits are kinda tough to find sometimes. Most places only carry 1-1/4 or 1-1/8...Lowes and Home Depot around here, for instance. But Sears carries 1-1/16 spade and boring bits. The spade bit was like $7 and the boring bits were $50+ (ouch!)

Even if the bored hole is a little loose, you can use an expanding glue such as Gorilla Glue to glue the pipe in.

What are you using to articulate the arms? You might be able to get away with a joint such as beelce uses here: http://www.hauntforum.com/showthread.php?t=17073


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## Buzz (Aug 26, 2011)

You all make a very good point about the diameter of the pipe and the size of boring bits. Might even go with 1/2" PVC. I'll have to make a few test pieces to see which will work best.


Victor said:


> I use three loop made from wire or zip ties for my joints. Shaved down T sections would allow you to keep from drilling holes into your PVC.


Thanks Victor, but I can't quite visualize your description. Do you have any pictures?



corey872 said:


> Is the PVC pipe giving you something that just a straight length of wood is not?


PVC pipe is so much lighter than wood, yet still quite strong.... And its hollow...



ouizul1 said:


> What are you using to articulate the arms? You might be able to get away with a joint such as beelce uses


Presently I'm planning to use a pneumatic piston to make the monster stand up. The motion of which will cause a cord to get taught. This cord runs up thru the PVC and is anchored in the forearm. As it gets taught the arm straightens. I love BeeIce's SOA skellys and plan to make a few, but I obviously can't run cord thru the PVC on that setup.


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## ouizul1 (May 22, 2010)

Buzz said:


> ...pneumatic piston to make the monster stand up. The motion of which will cause a cord to get taught...


Ah. Hope you post a few pics when you get it worked out, I can see some future uses for such a system.


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## halstaff (Nov 18, 2009)

Have you checked out the joints at Spider Hill Prop Works? http://www.spiderhillpropworks.com/store/index.php?route=product/product&product_id=49


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## fritz42_male (May 5, 2009)

I just flatten the ends of the pipe in a vice after heating and then attach ordinary hinges with small bolts. Depending on how much 'flat' you leave and the hinge type and position, you can get various angles of opening and closing.


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