Help: Ideas for assembling rafter units with plywood gussets

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I'm building a 32x32 ft barn with a Gambrel type roof. I have the design for a gambrel rafter arrangement which uses plywood gussets on BOTH sides of the joints between rafter sections. I plan to glue the gussets, but also nail them on as per the plan (concrete nails used due to high shear strength).
Can anyone suggest a good way to set up a jig for assembling these, that has some way to nail BOTH sides of the gussets without turning a large unfinished rafter unit over the other side up??
I could maybe put the whole thing up on the side of the barn frame...
I plan to lift finished units with my small crane, up to the second floor, so "right side up" seems like a good thing...
I know the commercial units use those metal gussets that are hydraulically pressed into place...
Anyone done stuff like this? Suggestions appreciated!
--
Regards, Terry King ...In The Woods In Vermont
snipped-for-privacy@terryking.us
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Well, I made a much smaller structure with a Gambrel roof and plywood gussets on both sides and told myself that if I ever built anything a lot larger that I would give serious thought to ordering them ;-). In my case, it wasn't a big deal to just flip them over. I know if your case, that's going to be more difficult, but I think it will be hard to get around having to do so. FWIW, I think the concrete nails are probably way overkill, but use what makes you happy.
todd
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I agree on the nails. The use of nails is to hold the plywood untill the glue dries. Once the glue sets up you could pull all the nails without any problems! Personally I would use sheet rock nails. Thin enough shank so the boards will not split, plus ring shank for a bit more holding power.
As for nailing both sides, that could be a problem! If you have a large flat ares to work with, you could build a jig supported by saw horses, and leave to joints exposed underneath. Then you could nail or screw from the bottem. Hope you have apropriate air nailer! Greg
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Cement nails - the square kind - would be less likely to split the wood.
With the inevitable variations in temperature and relative humidity, and cross-grain movement of the members, the glue would work loose. Then there's wind and snow loading ....
I think there's a good reason commercial trusses are made with fasteners that bend.

the
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My dad would argue with you. 24' truss rafters, plywood gussets, screwed and glued, then the screws removed. They have been hodling up for 30 years in his 24' x 32' garage. Pulled many engines with a come along and a 4x4 layed on the bottem truss run. Not one failure yet, in snow contry. He built them this way on a bet. His know-it-all neighbor said it would not work. Greg
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Greg is correct, this is the way wood aircraft are built as well, nails are just there until the glue dries.
Paul Hastings

and
layed
not
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Paul Hastings wrote:

And wood aircraft are exposed to a lot more vibration, stress and hostile environments than a roof truss and built to a lot smaller margin.

--
--John
Reply to jclarke at ae tee tee global dot net
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Neat, but is it code?

and
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not
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No code requirement at the time! Now many areas require engineered trusses, so DIY is out of the question. Greg
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Good, because the flexibility supplied by nail plates is required in quake and hurricane areas. Could pose insurance problems.
BTW, my shed has plywood gussets. Didn't glue 'em, because with nails, glue isn't necessary.

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They _require_ trusses? As in, won't allow stick-built rafters? I bet the fire departments aren't thrilled with that - truss roofs kill more firefighters than anything other than terrorist acts.
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Greg O wrote: <big snip>
I made my shop rafters on the concrete floor, with help from SWMBO, now deceased. Those included the horizontals and all angled parts. I used ply gussets on both sides of *each* joint and glue in *all* joints and surfaces and nails of some type. I just flipped them over and did the other side. That was a no-brainer for me. They have stood the test of time.
Hoyt W.
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Those metal gussets are the first thing to fail in a fire, causing premature roof failure. The steel gets soft _long_ before the wood burns. I'd avoid them if at all possible, they can change a minor fire into a "The roof fell in and we had to build over" fire.

Can you nail one side now, glue the other until they get up in place, and then nail the second side once the rafters are in position? Sounds like a great use for a framing nailer if you have (or want) one.
Dave Hinz
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I have only done this once. Thereafter I used purchased trusses.
My approach only allowed nailing gussets one side at a time. I built my prototype on the garage floor. Once completed I wrote down appropriate saw angle settings and traced everything on the floor with caulk. Once I did this, everything else was saw cuts and tinkertoys. When I got one side nailed the truss was plenty rigid for the flip over and finish. I too used roofing nails.
I don't know how many you have to build but if your jig up is too complicated, it could take more time than the trusses.

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I've built gambrel roof trusses and nailed the plywood gussets on by hand with a lot of 4D common nails. I had built a large work table on heavy duty saw horses with 3/4" plywood for a top. To this work table I nailed positioning blocks so that each precut board was held in position, i.e., the table served as a huge jig. There were 30 trusses, as I recall, and having this workbench height work table saved a lot of backpain and time. Each had to be flipped over so the other side could be nailed. The truss was strong enough to be flipped with no problem. Note that it was a lot faster when another guy helped with the job.
John
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Wed, Jun 30, 2004, 12:24pm snipped-for-privacy@terryking.us (TerryKing) says: I'm building <SNIP>
I got the distinct impression you mean to use a hammer, for nailing. I wouldn't. I'd use a nail gun. I'd make sure to hook it up to a compresser too.
JOAT "That's right," he said. "We're philosophers. We think, therefore we am." - From Small Gods
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why not use deck screws? I noticed they are using them in the demos at the BOB(big orange box) place. What is JOAT Jack snipped-for-privacy@webtv.net (J T) wrote in message (Terry King) says:

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snipped-for-privacy@yahoo.com (jack) wrote in

Why use deck screws? As others have said, the fasteners are really only there until the adhesive cures. I'd guess that one could shoot all the screws for a plywood plate in about the time it took to drive one or two screws. For a large barn, the time savings, as well as wear and tear on your elbow and shoulder, should pay for at least a rental on a framing nailer.
Screws are great in their place. I don't think this is one of them.
BTW, JOAT means 'Jack of all Trades.' It also means 'Practical fellow who, in his life, has seen a few problems, and found many answers.'
Patriarch
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Somebody wrote:
> why not use deck screws? I noticed they are using them in the demos at

Somebody else asks:

I have used plywood gussets, glue and deck screws to build a lot of temporary structures while building my boat.
It is a very strong joint and is easy to assemble.
The deck screw insures that you will get a thin glue joint.
Translation:
Thin glue joints are stronger than thick glue joints.
If you are doing a job on piece rate, a pneumatic nailer will surely be faster than deck screws, but will probably not produce an equal joint.
I use a pneumatic nailer strictly for temporary work, but then again, I'm not in the building construction business.
HTH
--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
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So every day I learn something. That's one of the things I love about the Wreck!
Thanks, Lew!
Patriarch
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