Official Luthiers Forum!

I'm ready to upgrade to fiberglass rods from the kite supply. Is 3/16" or 1/4" the best size?

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Steve Smith
"Music is what feelings sound like"

I use the 3/16 rods.

24" long 3/16" dia. with 1/2"-1" of deflection will provide the ideal clamping force (roughly 8lbs). If your clamping height is taller than 36" then move up to 1/4"

Thanks guys, I'm using a 24" deck so 3/16" it is.

Merry Christmas and Happy New Years!

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Steve Smith
"Music is what feelings sound like"

Keep in mind though that if your joints fit like mine do, you'll want to have 1/4" too for their extra clamping force.

Don't forget to by extra caps as well - they seem to magically disappear from time to time.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

let me warn against over clamping! too much pressure is as bad as not enough. 8lbs of force is just right for braces and most all joints with hhg or pva

Thanks Andy - that's a good point. I'll get some 1/4" as well plus extra caps.

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Steve Smith
"Music is what feelings sound like"

That may be true but sometimes you need a little extra to bend the wood into position e.g. when gluing a ladder braced back to the rim. I've got 3/16" rods and 1/4" - there's no way the 3/16" rods would have bent the back to meet the heel and tail and provided 8lbs force.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Andy I have built roughly 50 ladder braced back. I attached all but 4 to my rims using my go-bar deck and 3/16" bars.
now if you are using radisued braces glued to the backs in a radiused dish, the back will be very close to the rim shape anyway. So I am not seeing the problem But my intent is not to be argumentative. Also to note the rod lengths used to attach a back and side to a rim in a fixed height go-bar deck will be 3 to 4.5" shorter than those used to clamp braces to plates. This shorter column height make 3/16" dia rods much stiffer.

Well, I've only built one so take that . The deal I had was that both the top and back sides of the rim were profiled to 25 and 15' respectively. The top, being x-braced held its domed shape after gluing in the braces. The back, being ladder braced (braces were curved) was more cylindrical than domed i.e. the dome held laterally at 15' but was almost flat longitudinally (it had a little arc from the center reinforcement but not much). The top sitting on the rims was almost perfectly with no force. The back had big gaps heel and tail when touching in the waist and it required additional pressure to git it in there.

As to length of the rods, I use 24" rods and a 24" deck height for all my go bar-ing, I just bend them more to glue tops and backs. That's the great thing about fiberglass rods is once they've bent, they provide the same pressure irrespective of how much they're deformed. Shortening the length is a good way to get more pressure though.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

The top sitting on the rims was almost perfectly with no force. The back had big gaps heel and tail when touching in the waist and it required additional pressure to git it in there.

Just curious to know if this is a common thing or avoidable in some way as it seems a bit less than Ideal..

I only ask because Ive been there too!

As I mentioned, my experience with guitars = 1 so... the "issue" with ladder braced backs is that there's nothing to hold the form longitudinally. The center seam reinforcement's grain is oriented so that it gives least stiffness longitudinally. I've read here of a guy who glues a carbon fiber strip to the reinforcement and that holds the dome longitudinally. Is it really an issue though?

In another thread, most experienced builders think that after a few months any stresses imposed by bending the back or top to fit the dome are gone anyway. I just assumed it was typical.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Just a note, It is not a good idea to flex your go-bars more than 1" of deflection As most know adding more deflection to the bars adds no additional clamping strength but rather is stored as potential spring energy constrained between the clamped piece and the top deck plate. This potential spring energy is dangerous to both you and possibly the instrument if it gives way. I build bars specific to tasks so that I induce no more than 1/2-1" deflection.

Just remember to use eye protection while using gobars, installing and removing them. That's the one thing in the Mayes' tapes that bothers me is when he is gluing on the braces and his face is pretty close to the gobars with no eye protection. I hope he is taking better safty precautions these days. Although he might be able to pull off the pirate eye patch look.

John in an eye patch? Then all his DVD's would be rated "Ahrrrrrr"!

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http://www.presnallguitars.com

Wouldn't it be a good idea to fit the deck roof with a wire mesh, perhaps the type used for a light fence?
- i mean, line the top of the deck with the mesh, with a 1/2 inch gap or so.

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Build log

I have no problem with mine but I make my bars from hardwood.

Buy the 72" size and custom cut with dremel. I bought 30 of them and have in no way got them all cut up yet.

I think it cost me $70

Mike (www.goodwindkites.com)