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so, we all know what truss rods are...

well, I had a recent project where I figured about an 8' long double action truss rod would have solved some issues...yeah, 8 foot long...why? custom made hidden door where I worried (justifiably as it turns out) about wood moving over time.

now, a double action truss rod going down the length of the stile (vertical part of a door) would allow adjustment to at the very least contradict the movement of the wood...

so my query is, does anybody know of a person who could custom make such a thing at some reasonable sort of cost?

as a note, the clients I work for are very high end, so such an addition to a custom project would most likely be approved if planned for...

http://www.blanchardguitars.com/guitarp ... _rods.html

May not meet the "reasonable sort of cost" criterion. Lovely work, though.

cheers

Something that size ought to be a reasonable project for your local welding shop. Scale up one of the double action rods that you like and have the welding shop make it for you.

I heard of people making their own truss rods... just a piece of 3/16" steel rod, folded down the middle (or whatever length you need), and then both pieces could then be threaded. A block is made so that end is connected.

I could see myself making a Stewmac Hot Rod style truss rod this way... I got a mill so I can fabricate the block out of steel squares. The rod could be threaded. A truss rod nut can be silver brazed on to finish it off.

Problem I have with steel rods like this is that they are very heavy... it adds a lot of weight to the neck making the guitar neck heavy. For example that Martin U channel rod is very good but too heavy.

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Sounds like a single action rod in a curved bottom slot (aka: Gibson style rod) would be perfect for this application.

the whole reason for the concept of a double action rod is one cannot predict how a slab of wood is going to react...

I'll be specific...in the case I referred to my assignment was to make a hidden door...on the 'hidden' side I had a wall of vertical dime gap paneling of alder...so I carefully selected wood from what I was supplied, cut to rough length, saved the cutoffs for the same piece of wood above the door, milled the door pieces special, glued them up, sent them off to a wide belt sander, carefully cut to tight size, then used a track saw to slot the glue up to match the 1/8" gaps between tongue and groove siding...this panel was 5/8" thick...needed a door 1 3/4" thick...the backside looked like all the other swinging doors in the house and was made out of 1 1/8" thick maple for the rails and stiles and had a 1/2" piece of baltic birch plywood rabbetted into it to create a 5/8" recessed panel...the the alder was glued to the maple panel, and that's the door...what I envisioned and jokingly told my boss was that I needed a couple of 8' long truss rods to put in the stiles (vertical pieces of a door) to be able to adjust as necessary for any problems...would have been fairly easy...just slot the stiles for them and then glue on the alder...have the adjustment heads on top of the door...

anyway, such a thing is beyond me, and I really wouldn't trust it to a local person who has never made a truss rod...

This idea won't help you at all if/when the slab twists....


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Concrete high rises use to if not still, use a tensioning rod for their cantilevered decks. The rod ties back to the main column of the building and extends out the end of the deck, with the end treaded. Every few years the building corporation will have a company come and tighten the nuts on these rods, acting just like our truss rods.

Making a large 2 way rod is going to be somewhat expensive. Any good welding shop (which I use to work for) will be able to make one. This isn't rocket science and honestly a lot of guys out there welding are far smarter then us guitar makers...


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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

I'm not 100% sure but I think what you've got there is something called post stressed concrete. Concrete is very strong in compression but sucks air in tension. By tensioning a steel rod (which is great in tension but not so good in compression) you can increase the magnitude at which the concrete will hit a tensile load.

It's been years (since school) that I've had to think about that though so I'm probably explaining it wrong....check here for more info: https://en.wikipedia.org/wiki/Prestressed_concrete

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If you sketch it up and go to a welding/fabrication shop I'm sure the would make it.

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How about two single acting truss rods and inch apart,
going the opposite direction from each other.
Tighten or loosen whichever one is needed.

Ya that's it Andy. Post tensioning is what I was looking for.

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correct...long, tedious, story short: I made the wall of paneling with attached door jamb BEFORE I made the door...the jamb was dead nuts straight with parallel legs...

normally one has a door when one hangs a jamb...this allows for all things to be seen (at least as they exist at the time of install) and make things 'correct'...

my worry (well founded) was I didn't know how well the door would match the jamb...double action truss rod of 8' length would have allowed me to bow the stiles either way allowing for alignment with jamb on the lock side (hinge side has 3 Sugatsune hidden hinges that keep it locked in place at those 3 points).

in the big picture had I done said trussrod install I would have f*cked myself! damned superintendent never told me it was going to have a one sided deadbolt installed...!@#$%^&*()(*&^%$#@!...righto...1 1/8" thick maple panel to install a 1" bore deadbolt into (on lock side of door the alder overhangs 3.75")...now that was supremely fun to pull of and not destroy things...

anyway, thanks for the thoughts...guess I was hoping an individual who actually makes the things would step in and say "hey, I'd be interested"...if I ever feel the need for such a thing in the future, I'd rather trust it to somebody with some experience as opposed to a local shop with none.

as far as post tensioning, that was offered as an option to do, but I figured it really wouldn't offer what I needed, which was adjustability as opposed to stiffening