Neck reinforcement rods vs truss rod

[Dadagoboi]

Warmoth trussrods are single action, double expanding. They only put in back bow.

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I wouldn't design back bow into any neck unless it had a true double action trussrod tat is capable of adding front bow (relief).

The easy way to tell if you have a double action trussrod is to try to fully remove the TR nut. You can't do it with a DA rod.

 

[Gilmourisgod]

The DA rods I’ve used (LMI and Stewmac) can be put in a vice and visibly front or back bowed by turning the nut, which is captive. Is that considered a “true” DA rod?

 

[HaMMerHeD]

Seems like a good idea. No so much in practice. I didn't do it on purpose, but don't ask me how I know this.

Now, should I put rods in medium scale mahogany necks or not?

I would.

And in fact I did. The one mahogany-neck bass I made has CF rods in it. Whether or not it would have been fine without them...I don't know.

 

[reverendrally]

^ Yeah see @Bruce Johnson has a great theory about stiffness and tone and I'd rather risk a little stiffness and go for that big warm tone. Otherwise I put in bars and have the bass sound the same as everything else available. Thunderbirds came with mahogany necks and no CF rods. Everyone loves the warm thick TB tone (yes I know a lot of the sound is PUs too).

And it's medium scale, not long scale.

 

[Dadagoboi]

The DA rods I’ve used (LMI and Stewmac) can be put in a vice and visibly front or back bowed by turning the nut, which is captive. Is that considered a “true” DA rod?

Yes. Warmoth doesn't use them.

 

[saved]

I use carbon to avoid goof notes

 

[chinjazz]

I'm not sure how I missed this great thread? Thanks for starting it abarson.

So many good points brought out about the use of stiffening rods, or not.

I'm wondering at what point does one feel they need stiffening rods in conjunction with a DA truss rod?
Of course sealing the whole neck is an important step. Including the fretboard.

I'm wondering if there's a physical inspection of the neck blank before glue up of the fretboard?
Or is there no real way of knowing what the wood will do after glue up and put under tension?

I'm prepping up 3 neck blanks currently. One is an all maple 3 piece laminate. Dried and stable.
I cut this one up a few months ago, and just glued it up 2 weeks ago with West Systems 105/206.
It's flat and seems good.

The other two are 5 piece laminates (3 maple strips, with 2 walnut strips around the maple center).

I certainly don't want to make necks too stiff and cancel what the truss rod is for.

Ultimately, my question becomes, how do you know you've done a good job following the three
steps @Bruce Johnson shared on page 1? Or is this just one of those things you have to discover by doing over time?

Much appreciated! I'm still very new at it