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Go-Bars, Go-Bar decks and what about torsion boxes?
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Author:  Mike OMelia [ Sun Oct 17, 2010 10:09 am ]
Post subject:  Go-Bars, Go-Bar decks and what about torsion boxes?
I have often asked why they are named go-bars. Nobody seems to kmow. But I think I know. Its because they go everywhere but where they are supposed to stay. Maybe not an issue for smaller bodied guitars, but my harp bodies are hard to work with. I have tried double layers of plywood and all I get is a heavier, still flexible g--bar deck. The problem is in the number of go-bars used to hold a back or top down. Eventually, any manageable weight go-bar deck is going to flex. Each bar adds some 7 pounds of force. 30 go-bars is 210 pounds. That is enough to flex 2 2x4 sheets of 3/4 plywood. And it only takes a little flex to cause previously secured bars to fall off (GO-SOMEWHERE bars). And then its like the spinning plates problem!! Whaa!

The best and easiest solution is to use the bottom of wall mounted shelves... but that creates access problems.

So, I am thinking about building two torsion boxes. 1/2" plywood skins. Maybe a total of two inches or so thick. Thoughts?

Mike
Author:  runamuck [ Sun Oct 17, 2010 10:46 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Sounds like a good idea to me.

You go, boy.
Author:  Mike OMelia [ Sun Oct 17, 2010 10:51 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Well, now I am considering a hollow core door. Luan surface.

Mike
Author:  Rod True [ Sun Oct 17, 2010 11:21 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Mike, check out my shop in my signature line. Look at my go-bar deck/bench. The lower bench is 2x4 framed, like a wall, 2x4's are on 8" centers. Upper portion of the deck is on 8" centers as well I think with 2 - 5/8" plywood skins. A built in go-bar deck is nice to have. You can use the lower bench for multiple things as long as the upper deck is high enough, like mine is. There is also storage above the upper deck too if you build it in. Also you can glue up multiple plates at a time if the deck is large enough, say a back and a top.

I noticed I don't have picture of the deck in use so here you go.

Image
Author:  Edward Taylor [ Sun Oct 17, 2010 11:30 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Im with Rod. I have a deck built in to the end of my wall bench with 2x4 frames top and bottom on 6" centers, lagged to the wall and connected on the outer edges with wrought iron spindles, man that thing is solid.
Author:  Michael Smith [ Sun Oct 17, 2010 1:24 pm ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
The space in my shop is limited and I weld so I make a gobar deck out of light angle iron. I welded some wheels on it so it seconds as a rolling table. Having an Iron frame I can add as much bracing as needed to prevent over flexing. When I need it I lift it up on a work table and go to town.
Author:  Mike OMelia [ Sun Oct 17, 2010 9:02 pm ]
Post subject:  Go-Bars, Go-Bar decks and what about torsion boxes?
Well, mine has to be longer than normal, about 40"x30" or so for the harp form. Anyways, I bought one if those Luan doors, cut it half, dressed the cut ends, added 1/2" mdf on the internal sides, some 1/2" mdf strips on the outside surfaces ( to provide sturdy support for the lag bolts that hold the cast iron base plates for the 1/2" pipe spacers) and it works awesome. Very light given the thickness and no flex with 30-40 rods.
Author:  Mike OMelia [ Sun Oct 17, 2010 10:34 pm ]
Post subject:  Go-Bars, Go-Bar decks and what about torsion boxes?
I also coated the internal sides with thin drop cloth canvas. That helps keep the rods from slipping. Used Scotch 77 and a heated iron to apply. It is amazingly light given it's size and does not flex under load.
Author:  Mike OMelia [ Sun Oct 17, 2010 11:17 pm ]
Post subject:  Go-Bars, Go-Bar decks and what about torsion boxes?
Rod, thanks for the input!!
Author:  Dan Pennington [ Mon Oct 18, 2010 8:36 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
I think I read somewhere that 'go' is from Japanese. And exactly translates to "An open box kind of thing where ones uses sticks or slats or dowels or kite frame members or rods to clamp things down while one glues them together."
The Japanese are very efficient with single words to convey a large concept. :D
Author:  cwood8656 [ Mon Oct 18, 2010 9:06 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Mike,

My go bar deck has 3/4" plates with a square structure of maple 1x3s for support both top and bottom. The 1x3s are screwed together with 2 1/2" deck screws, and the plates are screwed to the 1x3s with deck screws in counter sunk holes. Maybe something like this would work for you?

Image

Chris.
Author:  Link Van Cleave [ Mon Oct 18, 2010 10:43 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Quote:
So, I am thinking about building two torsion boxes. 1/2" plywood skins. Maybe a total of two inches or so thick. Thoughts?

Mike


Mike, That will work just fine. I would make it more on the order of 3" to 3 1/2" thick though, 6" spacing on your grid. Do you have to make two ? Isn't the bottom one supported by your bench or does it hang off your support somewhere. In that case you would need to make 2.

Link
Author:  Steve Saville [ Mon Oct 18, 2010 11:24 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
penndan wrote:
I think I read somewhere that 'go' is from Japanese. .....

Hmmm - go in Japanese is the number 5. Go is a fun Japanese game with the object to get 5 in a row.
Author:  Dan Pennington [ Mon Oct 18, 2010 12:18 pm ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Steve Saville wrote:
penndan wrote:
I think I read somewhere that 'go' is from Japanese. .....

Hmmm - go in Japanese is the number 5. Go is a fun Japanese game with the object to get 5 in a row.



Yeah, go means five. In the old days in Japan, a carpenter was limited to only five sticks for his gluing deck. They were tough on carpenters in those days. laughing6-hehe

And, here's my deck. From my workbench to some particle board screwed to the floor joists in my basement. I use 3/4 by 1/4 slices of whatever wood is left over from my banjo block rim making process.
Image
Image
Author:  murrmac [ Mon Oct 18, 2010 12:20 pm ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Steve Saville wrote:
penndan wrote:
I think I read somewhere that 'go' is from Japanese. .....

Hmmm - go in Japanese is the number 5. Go is a fun Japanese game with the object to get 5 in a row.


Hmmm - could it be that penndan was just being humorously facetious ???

EDIT: darn, penndan just beat me to it ... gaah
Author:  TonyKarol [ Mon Oct 18, 2010 1:36 pm ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
I think your issue Mike might be tht the decks are a tad too far apart .. I use two pieces of baltic birch ply as the upper deck, 30x30 ... it is suspended dwon fomr the ceiling. The lower deck is the top of my router table/bench. make sure that the rods have enought bend to them that even if the deck flexes some, its not enough to allow any given gobar to straighten out. rememebr, no matter howmuch you flex the bar, you stil only get about 7-8 pounds of force.

I used this size deck for my harp too, and just did the remaining extension on the upper arm with small bar clamps and a caul or two ...
Author:  Ed Haney [ Mon Oct 18, 2010 8:44 pm ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
I made my go-bar deck base out of of 18"x24"x3" thick granite surface plate. I built the surface plate into a 2x4 frame table on casters so that it is easily moved and is a multiple purpose work table, perfectly flat sanding station and sharpening surface. The other benefit is zero flexing of the base keeping a radius dish truly flat. Its a handy table/deck.
Author:  Mike OMelia [ Mon Oct 18, 2010 9:39 pm ]
Post subject:  Go-Bars, Go-Bar decks and what about torsion boxes?
Nice stuff all!! Like ur pics Chris and pendan.

Link, if ur base is mobile ( as mine currently is) both boxes need to be equally stiff. If you make the top stiff and not the bottom, then the bottom will flex as well (newton). I'm glad I asked this question again. In the past I got the answer: add more layers. Enough layers and yes it will work. Apparently stiffness of the beam goes as the cube of it's thickness. But weight can be a huge issue. My current build was just an experiment. It's very light and very stiff... I can move it around with no help. But I will come back to this later. I saw an intriguing design for torsion boxes based on peg board material ( with and w/o the holes) that was extremely light and extremely stiff. Just hard board and yellow glue! Now, my requirement to deal with harp guitar bodies goes beyond what most of you care about. But I think it would be cool to see how stiff, light, and functional we can make future go-bar decks... A standard design, inexpensive and reachable by any guitar builder.

Thanks,

Mike
Author:  Dave Stewart [ Tue Oct 19, 2010 8:53 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
FWIW, I recently put together a setup that involved the vise-mouted jig (used for carving/assembly) and a plywood ceiling plate. The carving jig is fully adjustable for height. Worked out pretty well and takes up zero dedicated space.
Author:  Mike OMelia [ Tue Oct 19, 2010 3:15 pm ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Yup. Ceilings and floors are sort of torsion boxes.
Author:  Rod True [ Tue Oct 19, 2010 3:21 pm ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
Hey Mike, check this out ;) A different kind of go-bar deck
Author:  Mike OMelia [ Tue Oct 19, 2010 10:06 pm ]
Post subject:  Go-Bars, Go-Bar decks and what about torsion boxes?
Rod, that is cool, but how did you mount the dry wall to the cinder? The normal way is to put wood strips on the wall and along the base and ceiling using shot concrete nails. Thus, ur go-bar method is not needed. Finally, drywall in concrete will fail over time due to moisture wicking. You need to keep an air gap between the dry wall and the block.
Author:  Rod True [ Wed Oct 20, 2010 12:56 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
We just left the cinder block exposed and painted it. No drywall over any cinder block ;)
Author:  David Barnett [ Wed Oct 20, 2010 10:03 am ]
Post subject:  Re: Go-Bars, Go-Bar decks and what about torsion boxes?
From the French goberge, perhaps because a row of these resembles le squelette de la goberge, the skeleton of the pollock.

http://tinyurl.com/goberge

Illustration, lower left, in caption.
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