truss rod routing

[vilered1]

what kind of truss rod route are you all using? I used a curved route on my last build, but it was a bass. I'm getting ready to do two LP JR necks and I'm thinking I'll do the same on them. I have some vintage style 1 way truss rods and the necks are 1 piece quarter sawn Sapelle. I've seen flat routes done for the 2 way truss rods, and I've also seen a method where the rod is angled in the neck. I want to be able to go kind of thin on these necks, so I'm not realy sure what the maximum depth should be. any advise?

 

[gator payne]

I assume you mean the profile inside edges of the rout. If you have a two way rod like LMI's or Allieds then you want square profile because they are designed to set in a square profile slot. Some others can acommidate a 50% radial profile slot. Other can accommidate a full radius profile slot. It is all dependent on the type of rod you use.

If you tried to put a LMI TSRD rod in a slot with radial profile, because it has retangular nut ends it would not set flush because the corners of the nut ends would bottom out on the radii before it would be fully seated.

So It all depends on the rod being used.

 

[vilered1]

I appreciate the info. what I am referring to though is any variation in the depth or the truss rod channel along the length of the neck. so you might be cutting 3/8" at the nut, 5/8" @ the 8-12th fret area and then back to 3/8" @ the neck heel. I have a Gibson neck that I can chop up and get the right curveature, but I'd rether keep it for a later project.

 

[Reverend D]

For the type of double acting truss rods that a great many of the people use here (Hot rods, LMI, Allied and other double truss rods) the slot is cut square and the channel is the same from the nut to the end of the truss rod slot. Check each site for installation depth and width's. For example Stewmac and the hot rod sells a router bit that fits the rod (I believe its .220 if I recall right). So the simple answer, chuck up a router bit set the depth and cut it.

Regards,

Don

 

[vilered1]

I'm up for trying it if you guys think that a flat rout will work with a one way rod. I've been racking my brain trying to come up with a jig for a curved channel. I was going to draw out a curve on a board, cut the curve out on the band saw and then saw the board in half so that I had two matching sides, then build a sled for the router that could just be clamped to the neck blank... I still may go that direction. on my first build I made a 3 piece neck with a 1/4 inch piece of walnut down the middle. I cut the channel out into the walnut on a scrool saw before gluing the 3 pieces together. when it was done I just dropped the rod in, clamped the filler strip in place and glued it up.

I plan on doing a 2-4 guitars a year, so making a fixture to do this job is important to me. the 2 way rod with a straight channel sounds pretty straight forward, and honestly very appealing, but I have a few thoughts/ questions about the 2 way rods that maybe you folks could answer...
my guess is that they are heavier and could cause neck dive, and will brighten the sound of the guitar more due to a larger amount of steel in the neck. the brightening may not be too bad of a thing but the guitar's balance and playing position is very important to me. any info or opinions would be appreciated.

 

[bruce bennett]

a one way rod needs a curved bottom slot in order to work properly, and the dual action rods I use still require a rounded bottom.. but, if your useing a Gibson styled rod then I have an easy way to make that curved bottom rout.

Ok . now that I have my blank and I'm satisfied that its diamensions are as close to factory as i can get.. I need to start working on duplicateing the factory style truss rod.. so I need a jig to make the curved bottom slot in the neck blank.. and this is how I did it..
I started with a 1/4" thick piece of baltic birch and routed a 1/2" Slot in it about 20" long.

I then added some small riser blocks at both ends of the slot on the "down" or neck side of the birch.

i then planed of the blocks to a desired thickness .. that took a while to come up with that thickness and I measured a lot of old broken gibson
necks to come up with that figure.

 

[bruce bennett]

here is more of that thread.

this shot is of the blocks on the headstock end of the neck you can see it isn't a very high angle on these truss rods at this end at all.

then I drilled two holes about midways down ( actually it was exactly where my "angle" was in my drawing) and I countersunk the holes on the "top" side of the jig,

of course whenever you make a jig you draw a centerline first. that way you always have a refernce later after you have removed material.. Here I was checking my centerline on my neck blank..

 

[bruce bennett]

and the last bit.. Hope this helps!

a small block drilled with corresponding holes and some long bolts and nuts finish out my routing jig..

and about now your asking "how the F*** is that gonna work?"
well here is how..

nice curved bottom slot!

 

[bruce bennett]

while tis true that the heavier dual action rod does add some weight, its not that much .

and even if you DO use the dual action rod i HIGHLY recommend you install it deep and add a filler stripe. this keeps down any "truss rod rattle" and it helps even out the pressure this type of rod places on the underside of the fingerboard.

but either way you go.. that same fixture will work for either rod.

 

[silverkw]

and the last bit.. Hope this helps!

Bruce, this is freaking Awesome.

 

[bruce bennett]

heres the rest of that thread, its all about re-making a Les Paul Custom neck.

http://www.mylespaul.com/forums/luthiers-corner/137017-les-paul-custom-rescue.html#post2609941

and the chick in your sig. photo is freaking awesome.

 

[dazzaman]

Bruce, this is freaking Awesome.

+1

I had no idea where that was going until the last post, and then it was a "That is so simple why didn't I..."

 

[fatdaddypreacher]

not to start the whole truss-rod channel issue all over again, but i thought i saw somewhere when i first stated 1 1/2 ago that some single action slots were flat bottomed (but angled---deeper at the bridge end by apx 1/8"), and some were curved, that it really didn't matter, so long as the flat bottoms were below the center line of the neck.

could that be clarified, as i have used flat bottomed, angled channels on my builds. the rods seem to work just fine...at least now, but don't know if i need to go to curved bottoms where i used one pc rods.

thanks for the thread V1. lot of good info in just a few posts.

 

[bruce bennett]

not to start the whole truss-rod channel issue all over again, but i thought i saw somewhere when i first stated 1 1/2 ago that some single action slots were flat bottomed (but angled---deeper at the bridge end by apx 1/8"), and some were curved, that it really didn't matter, so long as the flat bottoms were below the center line of the neck.

could that be clarified, as i have used flat bottomed, angled channels on my builds. the rods seem to work just fine...at least now, but don't know if i need to go to curved bottoms where i used one pc rods.

thanks for the thread V1. lot of good info in just a few posts.

I'm sure Gator may chime in on this, and I'd like to hear his thoughts on this..

but my experience has been, that if your useing a one way "gibson styled" rod, as long as the bottom of the slot has any curve or even angle, so long as the rod itself has a "bend" of some degree. it will work.

as for the bottom shape of the slot, if the rod is round, I would use a round nosed ( bullnosed) router bit in order to make the rod fit as tightly in the slot as possible to keep down any truss rod rattles.

but there is no law that says you couldn't use a flat bottomed slot.

and I've heard about the whole "lower than centerline" thing.. but I've done a few super shallow and they still worked.... although maybe they were less predictable in their operation. and of course they "ran out of working room" very quickly.

one of the real issues with these rods is where the apex of the curve/angle is located along the necks length, and how deep to make the curve/angle..
this changes with the style of neck your building.. example: a les paul neck which has the heel starting at the 14th fret won't need its truss rod apex as far forward as say a DC LP JR would with its heel starting at the 18th fret. ( more unsupported neck than a les paul)

these two things have the most effect on the operation of the rod and how effective it will be in counteracting forward bow on the completed neck.

Terry C Mcinturff had a great thread on this over at TGP ( the gear page forums) a few years ago. he covered a lot of details in that thread and a great deal of the theory on the use of these rods.

here it is.. http://www.thegearpage.net/board/showthread.php?t=404471&highlight=truss+rods

 

[bruce bennett]

If you tried to put a LMI TSRD rod in a slot with radial profile, because it has retangular nut ends it would not set flush because the corners of the nut ends would bottom out on the radii before it would be fully seated.

So It all depends on the rod being used.

I do exactly this Gator,

I use a 1/4" chisel to inset those short square end blocks. they only need like a 1/32" deep square bottomed channel to sit in.

and the square channels tend to hold the rod in place and reduces any "twisting" motions when actually useing the rod.

 

[vista]

I was too lazy to make a jig for routing an arched slot so working on an idea from Roman Rist, I did this;

Route a straight slot ~1/2" deep
Cut two pieces of filler,~7" long, taper from 0-1/8"
Glue in these 2 pieces at either end of the bottom of the channel
Bend truss gently by hand so it lays against the bottom
Shape top filler strip to conform as close as possible, then glue and clamp in.

Brian

 

[jonas335]

Thanks, Bruce, for this brilliantly simple idea. I've used a variation of this to mark curved lines in carpentry and cabinet making, but never thought of using it for a TR channel. This will be used on this years LP build...

 

[Paul Rhoney]

A single-action rod in a straight channel will work, the difference is it takes a lot more turns of the nut to get it to do anything than a single-action rod set in a curved-bottom channel.

 

[vilered1]

Great Info! I had imagined a similar jig but seeing it in action helps so much. I hope to get my neck jig up and running and get some pics up for you guys this week. I'll also check out that thread on the gear page. Do you guys use cardboard "straws" when you install your truss rods? I did on my last build. I liked it because it helped to hold the rod in place while gluing and placing the filler strip. also didn't have to worry about getting any glue on the rod at all. rod rattle is my biggest fear... I'd have a hard time not scrappin a neck where the rod rattles. thanks again!

 

[emoney]

If you pay close enough attention to your filler strip, and the width of your router bit,
then truss-rod-rattle shouldn't be an issue. Don't install a loose filler strip, as that can be
a quick source of unwanted noise because you've left room for the rod to rattle. I've
built only 5 necks, but they've all had flat channels, single "Gibson-style" rods and none
of them rattle, and they all do their job.....at least they're doing it now.

I think some of the biggest issues that develop come from too much excess room in
the channel and a weak filler strip. Gotta remember that the filler strip is an integral part
of the whole equation and not just a cosmetic addition.