strongback construction

[samiller]

I have need to put together a strongback to hold station molds for a series of new projects. I'm hoping to use (and reuse) it to build between 4 to 6 canoes and wherries varying from 14 to 16 feet in length. Given the sorry state of the plywood and dimensional lumber supply to day, what is everyone using to make strongbacks? My thought was to use "engineered lumber", perhaps bridging 2 16-foot TJI (the floor joists made with a web of OSB and flanges of veneer lumber) into a box. A 16-foot strongback so constructed won't be quite as light as I would like (~73 lbs. + the bridging) but I should be able to build it so it can be dismantled for storage. Thoughts or advice?

-Sam

[Todd Bradshaw]

I always liked a 6"x6" 3-sided (top and sides) box beam made from 3/4" plywood with internal blocking, varnished inside and out and divided into two or three bolt-together sections.

[JimD]

This gets plenty of use and reuse. Its one inch plywood and construction grade 2 x 4s. Straight as an arrow, held together with screws. No glue. Easy to take apart and reassemble. Has a shelf underneath for tools, etc.

Edited to add: Its pretty much the plywood box beam Todd describes. I think its ten inches wide, though. The stability of top and sides all being made with heavy plywood is what keeps it true.

http://www.imagestation.com/picture/sraid165/p1c0ae4152c43e98921a2442f1f9ff4a8/f46f65c0.jpg (http://javascript<b></b>:downloadOriginal())

http://www.imagestation.com/picture/sraid204/pe2cd128dbe5399f1eeeb8f1824625dbd/ef51a54d.jpg (http://javascript<b></b>:downloadOriginal())

http://www.imagestation.com/picture/sraid204/p5294c5e7797588e945d43de87a487dd7/ef51a543.jpg (http://javascript<b></b>:downloadOriginal())

http://www.imagestation.com/picture/sraid205/p3cbee452a753eec6f18c67a14acdb032/ef0daa3f.jpg (http://javascript<b></b>:downloadOriginal())

[JimD]

Yes, concrete has its uses :)

[George Ray]

http://ec1.images-amazon.com/images/I/31H7NowKsqL._AA280_.jpg

Makita 12V Cordless 1/4" Impact Driver Kit w/ Light 6916FDWAE
http://www.amazon.com/Makita-Cordless-Impact-Driver-6916FDWAE/dp/B000FHDSCU/ref=pd_bbs_8/104-8106137-6398351?ie=UTF8&s=hi&qid=1188905820&sr=8-8
************************************************

I have been using this tool (w/o light) for years to build temporary and take apart items. A collection of different length deck and drywall screws and you are in business. It is amazing

[Dale R. Hamilton]

http://www.imagestation.com/picture/sraid225/p0e56e4ca76ac7fca0153466905b35ce5/e933cc81.jpg

Sam- Here's the building jig I use to build 16' mahogany runabouts. Notice the jig itself is fully boxed with 3/16" steel bos beams thru bolted every 30". It cannot move or distort. Plus the whole thing can be raised/lowered by means of the hydraulic jacks. Also it rotated 360 degrees with detentes every 2". Jinally when rig is rotated at 180 degrees, you have a 16' long table to assemble long members. I put this together fro about $1200- cheap when you consider how easy it makes building. It would adapt very easily to your work.

Dale

[Dale R. Hamilton]

http://www.imagestation.com/picture/sraid225/p0e56e4ca76ac7fca0153466905b35ce5/e933cc81.jpg

Sam- Here's the building jig I use to build 16' mahogany runabouts. Notice the jig itself is fully boxed with 3/16" steel box beams thru bolted every 30". It cannot move or distort. Plus the whole thing can be raised/lowered by means of the hydraulic jacks. Also it rotated 360 degrees with detentes every 2". Jinally when rig is rotated at 180 degrees, you have a 16' long table to assemble long members. I put this together fro about $1200- cheap when you consider how easy it makes building. It would adapt very easily to your work.

Dale

[Don Z.]

Dale,
That is way cool. I don't suppose you have more photos? Construction plans?

[George Roberts]

"Given the sorry state of the plywood and dimensional lumber"

I use 1/2" plywood for both the strongback and the forms. I set the strongback on top of a 10' long bench - a 1x6 with a set of legs on each end.

---

I can set up 4 in my shop at a time with enough room to work on one/two boats at a time. They are light enough move around every day as needed.

[cs]

I built a strongback for my Micmac canoe from an old LVL that was left over from a job. I ripped it in half and than screwed it together to create a "T" and it workded great, but heavy.

Chad

Just noticted that down there in the similar threads there is the link to my orginal topic on this.

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=2788

[Songololo]

The strongback for my current Wee Rob project is made from two of these :

http://www.imagestation.com/picture/sraid225/p29778629f346645a215f9e427c1aefb6/e7d5a632.jpg

To give this:

http://www.imagestation.com/picture/sraid225/p65112126feb7cf89796e845e746e8a03/e7d5a62c.jpg

It is all mounted on lockable swiveling castors
http://lh5.google.com/Songololo/Rt2fUEuLt6I/AAAAAAAAAJg/egU_R-PN18g/DSC05246.JPG

http://lh4.google.com/Songololo/Rt2fS0uLt5I/AAAAAAAAAJY/EB9TOjyczV4/DSC05250.JPG

They allow it to be moved around the limited workspace and then locked in place. The boxes are made from 1.5mx0.5mx27mm shuttering plywood sheets - they are straight edged, flat and square.

The boxes will be used for shelving once they have served their current purpose ... until the next project that is :) ...

[Dale R. Hamilton]

http://www.imagestation.com/picture/sraid225/pbaa584e10a2f4c47ff2e117284254dbc/e933cc06.jpgmore picshttp://www.imagestation.com/picture/sraid225/pd9f21341ce66389b2767768e10541ea9/e933cc5a.jpg

[Chan]

Uh Oh I think I see a spotless shop!

[JimConlin]

I have two strongbacks. For small boats, there's a box beam with 2x4 sides and ply top & bottom. It's 12' long and there's a plug-in extension (2x4's and ply) for longer boats.
It's curled a bit over the years, but it's pretty straight. When not in use, I've screwed it to the garage ceiling which seems to suit it.

For larger boats, i have a box beam of nominal 10" i-beam joists with play top & bottom. It has been quite stable.

The benefit of either of these is that the setup can be moved around the shop and even tilted to save the back.

I do like that rotisserie.

[pipefitter]

And for the earthy outdoor types with sandy soils,I concreted these T's made from the straight sections of 10' pt 2x4's for knowing what PT 4x4's can twist /warp into when they dry. The boat was light enough for 2 but I needed to straighten the not so straight,straightest 2x8 I could find.

http://home.earthlink.net/~tigmaster41/sitebuildercontent/sitebuilderpictures/00610016.jpg

When the boat was flipped over, I merely stubbed them off and attached a crude cradle to it built from what I cut off. It served me well and I was able to break it apart and the boat now sits in the same spot on it's trailer.

http://home.earthlink.net/~tigmaster41/sitebuildercontent/sitebuilderpictures/321a.jpg

Notice the long bench on the saw horses. It was designed to pinch the A$$es that would stop by and try to distract me from my work for conversation sake.

[Songololo]

In a prior kayak building project I made use of the following strongback:

http://www.imagestation.com/picture/sraid225/p207d648c2d81315f167428e37e028b0e/e7d59ef2.jpg

http://www.imagestation.com/picture/sraid225/pdf2676d80aef75486631514534f0ecd9/e7d59eef.jpg

It was made up of a lower, 3 layer sandwich of 1.5m overlapping beams bolted together and a finished off with an upper, screwed on top cap.

Advantages:
- I could make use of available offcuts for its construction
- it can be dismantled into shorter lengths for easy storage.

Instructions and more pics can be found on Tom Yost's site at: http://www.yostwerks.com/Stronga.html.