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Filippo, I agree that the Stew Mac rod requires more depth in the slot, and that's why I don't use them either. But I get a difference of .085" which is a little less than 3/32", still too much to give up.

Chuck

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Ah, that's a bummer. Had the same thing happen to me with a HotRod. Blew out the back of the neck on an OM. I pulled the fretboard, glued the neck blow out, added a bit of wood and re-routed for the allied rod. The allied rod for steel string is also a bit longer so the end is more into the volute area. All has been good now for several years and the rod adjusts just fine.

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Steve Smith
"Music is what feelings sound like"

I've used 17 of those hotrods so far. Given that these necks are relatively thick, like a Les Paul neck, I can't complain at all. But I plan on using an Ibanez profile that I really like and this big ol' brass block is completely out of the question.

So your point is well taken. If I ever use a lower profile rod and it's trouble free (like the hotrods) I doubt I'll go back to the hotrods. I have to say though...I worry about that welded joint as opposed to a one-piece, machined block.

I have a notion for a single rod, dual acting truss rod that would be easy enough to pull off using the cnc machine. I'll probably end up using that exclusively...after I invent it.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I've had the weld fail on an allied rod in a customer's guitar; he was not a happy camper. Each rod design has pros and cons. I have used lots of the stew mac rods and never had an issue.

If the neck will be thin you can use a thinner fretboard to effectively make the channel higher relative to the back of the neck.

The weld on the Allied looks like TIG, which is good, but it also looks like they didn't bevel the edges and used no filler rod. That means the weld won't have much penetration unless the welder blasts it with current, which they can't do because it would mess up the threads. The weld bead appears concave -- is that the case?

For some insurance, you could silver solder the joint.

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David Malicky

I can see the rings from the filler rod in the picture. It looks like they fixture it with a small gap between the pieces, which is perfectly appropriate for small pieces like this. Maybe not 1" steel plates on the deck of a ship...you would bevel those...but not here.

Check out Cumpiano's method for installing this style rod. He makes a little channel for the filler strip to fit into, instead of putting it directly on the rod. This way the filler strip doesn't bend the rod and if it ever breaks you can simply slide it out and slide in a new one. Neat idea.

Todd where can one acquire these Martin rods? Martin directly? Or are these the same ones LMI is selling as martin style made by Gotoh? Are they one in the same?...Mike

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Another day, another dollar.

I wasn't too fond of the hot rod for a different reason.
I didn't like the top rod being threaded--which I realize is part of that design.
But it rattled and vibrated annoyingly. I had to wick some super glue into that back block to immobilize the rod and stop the clatter. Needless trouble.

Steve

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From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

Filippo, how deep of a channel did you make, was it capped? I have used a couple and thought that the filler above would make it way too close for comfort. I also considered epoxying some cf under to help bolster the wood, any thoughts on the value of that concept? Was the blow out behind the nut? I still have one on the shelf destined for an electric, certainly would love to avoid that issue.

I'm actually on the East coast this week in my old NJ home town, my daughter is experiencing both traffic and humidity for the first time.
Rob

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[quote="lex_luthier"]I've had the weld fail on an allied rod.../quote]

I had the weld fail on an Allied truss rod like the one shown in the photo above last year before I ever even got it installed- a single turn on the workbench jut to see if it was working correct and it snapped at the body end; clearly nobody ever tested it.

Good eye and points, though weaving w/o filler makes those rings, too. Their fineness and uniformity looks to me like weave w/o filler, as curiously, the weld on the other end shows filler: http://www.alliedlutherie.com/images/Tr ... ussrod.jpg

I was thinking what looks like a gap is shadow from slightly chamfered edges. While a small part, the steel is 1/4" thick... a structural joint would need either a bevel with filler, a large convex bead (too wide for the slot), or a blast of current.

The weld looks concave from the 2 pics, which is the normal outcome for a butt-weld w/o filler. That would put the bead in tension on cooling and prone to cracks. It's not surprising these are failing: little penetration, no filler, base-metal bead in tension. Silver-soldering would have the 2nd benefit of stress-relieving most of that tension.

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David Malicky

They do say in their instructions on the site to test the rod before you use it:

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Steve Smith
"Music is what feelings sound like"

Hey, Dave. I just went downstairs and checked out some of the rods I have here. They are indeed beveled as you guessed. Mine are not near as concave as the ones in the picture. Just slightly...enough that it ensures the weld doesn't poke out. Maybe the picture is exaggerating that, our maybe they've changed something in their process.

I must be an outlier, because I've used Hot Rods, albeit made by a machine shop in lengths useful to my various neck lengths for baritones and fan frets, and have never had an issue. Ever. I do bed the bottom and top of slot with caulk to avoid any rattles, but I've had that issue with LMI's rods, which have broken twice. A proper weld should be stronger than the metal itself. LMI's "welds" look pretty, but my observation is that they're not using enough juice. It's a fill, not a weld and therein lies the problem. When my rods broke there appeared to be no penetration of the weld, it was sitting on top of the metal rather than being one.

How thin are you making your necks? With a .830" at the nut, and a .25" fingerboard, that leaves you .143" of meat under the block.

"Check out Cumpiano's method for installing this style rod. He makes a little channel for the filler strip to fit into, instead of putting it directly on the rod. This way the filler strip doesn't bend the rod and if it ever breaks you can simply slide it out and slide in a new one. Neat idea."

Hi John, I tried to find this on Cumpianos website, but couldn't. Where can I find this at, I'd like to see it?
Thanks in advance.

Having done a fair amount of TIG during my stint as a fabricator and having examined and used the Allied rods the welds are fuse welded at least in the ones I have looked at. No rod used but perfectly strong if done right. I know they had a bad batch a while back but as far as I know they had corrected it. Test any rod first before installing.
L.

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Cut to size.....Beat to fit.....Paint to match.

You can see videos of it on LuthierTube. It's also in his book, I think. I'll explain it to you, though.

After making the slot for the rod, take a 1/2" straight bit and set the depth to the exact top of the rod. The way he does this is he installs the rod and then takes a pencil and marks where the top is. Then he removes the rod and makes test cuts lowering the bit until he just barely removes that mark. Once you're set, just make a full pass and make a channel with that 1/2" bit, stopping at the end of the truss rod. You end up with a neat, little channel to lay a filler strip into. Then you just have to round the end of your filler strip because the 1/2" bit will leave a round end.

You're not alone. I've used at least 80 of them with no problems. My necks are as thin as .770" but I use a thinner fb and always at least .125" under the block.

It probably also helps if you don't need to use the rod when the guitar is new. I rarely need to tighten mine more than snug.

Anyway, if the rod is blowing out the neck, I don't see how it's the fault of the rod. The rod is doing it's job.

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http://www.chassonguitars.com

Nope, nothing wrong with the rods as long as you can provide adequate wood underneath. I would just rather have a thinner rod that allows me to leave more meat underneath.

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Steve Smith
"Music is what feelings sound like"

This is the Allied rod that failed me in case it can help settle any speculation on how they're done... now I'm wishing I had taken a more detailed picture.

That picture shows it all. There's no penetration on that weld. As Dave said, and now I agree, no filler is used, and on your particular rod there was only a superficial melting of the metals. Yah' just can't do that, and only the welder knows what the puddle looked like at the time so it's difficult to inspect. It really makes me wonder why they're beveling the surfaces if there's no plan to add filler back.

I've used both Lmiis & Stew -mac rods for years.
Before that I made my own.

The Lmii rod can rattle-I put used sandpaper(1000 grit) in the channel
to get a tight fit -NO rattles.
Never had one fail.

I use the Hotrods and have had no problems at all with them.
Use a cove bit & square the brass block areas with a chisel.
As Steve said-it's not the rods fault if the design of the neck is
too thin.

Mike

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Mike Collins

Filippo...do you use CF rods in your necks? I've used many SM HotRods and have had 2 blow out the neck (accompanied by some overzealous tightening...). But these necks both had CF in there and I theorized that maybe the resistance created by the CF rods worked against the action of the truss rod and caused it to pop out of the neck. Anyway, as a result, I've moved to a slightly thinner fretboard (about .200") and Allied rods and stopped using the CF several guitars ago. I like this combination.

Where are all of these necks breaking, anyway? Is it happening right at the block? I've only used the HotRod once or twice (because I liked the wheel adjustment for those particular builds but got away from it). Anyhow, I guess it really doesn't matter but I'm just curious.

John, thanks for checking those out -- that's helpful to know. I wondered if the little chamfers were that way from the mill, or maybe the edges were too sharp so they deburred.

Welding without filler (autogenous or fuse welding) is ok for lightly stressed parts like sheetmetal. I also use it sometimes as it's faster and often looks better, especially for outside corners. But steel filler rod has deoxidizers that keep the bead ductile and strong, and the fill prevents concavity.

Sheetmetal butt-joints can be done like the Allied rod, but as thickness increases, the penetration decreases, as the base metal sucks more heat away. I know I've been surprised by this effect, getting a 32nd of penetration after what seemed like plenty of current.

As David said, a properly welded joint is stronger than the base metal. For many parts, a shortcut can be fine if it's considered, or you're lucky. Welding gets a bad name from parts like this truss rod, that have had too many unconsidered shortcuts.

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David Malicky