Custom Aluminum Neck but NOT a Luthier!

[Deleted member 368008]

No aluminium neck, bridge, or tuners will do my way. I will not accept any aluminium which holds or let the string pass over, maybe only guitars pickups. No matter how you treat aluminium with coating, aluminium is made to extract and compress, swell and shrink, due to temperature shifts, and so very quickly. By 30-40 %. Wood or stainless steel has greater resistance to that, and although they will shrink or expand too, it is later on like 1 2 hours time and by a far lesser degree like 10 %. I have heard, and tried all of Strandbergs headless designs with headless tuners in "military grade alu" and they all go slightly out of tune, on stage in the stage lights. And certain whammy bar bridges, where you cannot solder ground wire onto because nothing sticks to aluminium. Which defies the purpose behind the idea of headless basses and guitars regarding staying in tune. Anything that holds the strings should be the same material as the strings are made of. But stainless steel necks would be too heavy so I would go for anything graphite instead. Strings DO expands/contracts to temperature changes too, going out of tune, but you do not have to exacerbate that with adding another factor that expands/contract even more.

And if it stays in the sun, or outdoors... ffs. Keep it to sturdy wood, or the graphite variants still left out there. This lightweight fad has gone overboard.

But still, good luck with your project! Aluminium doesn't warp to moisture at least, but that's all.

When I worked at the wholesaler for Travis Bean (Hagstrom Sweden) in the beginning of the 80s, we had HUGE problems selling them. It's Scandinavian climate, and the few we sold came back...they went south later on.

 

[Deleted member 368008]

A cool aluminum neck would not have a fretboard. Of course google showed me that someone has already done a version.

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Gittlers are/was not ever made in aluminium. Stainless steel or Titanium.

 

[Deleted member 368008]

Headless + aluminium. Les Paul knew a thing or two. Acknowledged here, that it was a bad idea.

 

[WilbursaurusRex]

I'm not a luthier either, but I was a pro machinist for a while. My thoughts / research on a DIY aluminum neck, take them or leave them:

1. ***Definitely*** plan for a truss rod and especially if you're doing a 2-piece. A friend of mine kit built a guitar with a no-truss-rod aluminum neck (unsure of the mfg.), and he fought the setup tooth and nail to get it even remotely playable (shimming, filing, leveling, etc.). To this day, it *still* needs more work to be gig-able. OTOH, a truss rod would have made it a snap. Sure, aluminum is stiff, but 200+ lbs of string tension is no joke. (see attached pic - this was for an E-A-D-G-C project I did long ago, what a coincidence!)(this is also a good reference for "occult" projects: Kalium Music | String Tension Calculator ) edit: I'm not 100% sure how Travis Beans or Kramers, etc., get setup, but I am super curious. String tension has to be a factor!

2. How do you plan to attach the fretboard? My big idea is a simple tongue and groove "dry" fretboard with "inlays" that are actually flathead (or low head) sockethead cap screws, which are then shaped to match the fretboard radius once torqued. Depending on what frets you choose (your fingers never really touch the fretboard with 6100s, for instance), re-shaping may not be necessary with a nicely dressed relief. With first fret "inlays" and bolts on the usual inlay positions, I think that would be enough to hold it together. If you have time and can bench your own tools, I would do a taper on the tongue and groove and offset "tune" your program (without breaking your setup) until you achieve the fit you desire.

3. 7075 wouldn't even be my third choice. Left untreated, it will get chalky and scaly. Depending on the budget, check out 7050. It's 6061 on steroids (and weldable), otherwise 6061 will work fine and be easiest to obtain.

4. Does your CAM package have thread milling capabilities? I would definitely do thread inserts for all threads (mandatory inserts in aluminum is a MIL spec, so you know it's good!)

5. What CAD software do you have?

1) That sounds reasonable. Would a trussrod still do much in an aluminum neck? I have wondered the best way to put relief into it, and I havent found much info on it. Milling it into the neck? adding some in your fret job, etc?

2) My initial thought was to mill a diamond pattern in the aluminum contact faces to increase surface area, then sandblast it, and use an epoxy/adhesive of some kind.

3) I didnt think about 7050. Whatever I decide to go with, I was wanting to coat it. I not sure what the best option may be, but I was considering DuraCoat to seal and protect it.

4) Ill have to check on the thread milling. I was either going to use fusion 360 for cad and cam, or fusion for cad and mastercam for cam. I also have access to solidworks, but I prefer 360's layout. Either way, I was already thinking about inserts. Better safe than sorry!

I agree with almost everything Anthony Fury said. I'm an experienced Luthier and Machinist, and I have messed around with aluminum and other non-wood necks.

Use 6061. I can't think of any good reason to use 7075. It's 3X the price of 6061, harder to machine, has that chalky problem, etc. 6061 will be so much nicer to work with.

I agree about the truss rod. You really should plan on putting one in. You're going to need to hog enough aluminum out of this neck, just to get the weight reasonable, that it will have some deflection under string load. Can you design this thing to deflect accurately to a fixed amount, in all conditions? I doubt it. You need to be able to adjust that deflection under load. That's what truss rods are for.

I agree with your choice of Richlite for the fingerboard, assuming that you want something other than aluminum. Richlite will be the closest to aluminum in thermal expansion characteristics.

You can epoxy Richlite to aluminum, and have the joint strong enough to take the loads.....but you need a lot of surface area for the glue joint. I recommend that, after you mill out most of the aluminum on the inside of the neck, add a thin top plate of aluminum on the top surface. Like 0.063" 6061. You could heli-arc weld it along the edges or attach it with countersunk screws. Give the neck a full smooth surface to glue the fingerboard to. Rough up the aluminum and the Richlite, and use a good marine epoxy.

Yes, use threaded inserts for any important structural threaded holes. Heli-Coils are fine, or there are many other types available. I personally would use threaded brass inserts and stainless bolts. I use that combination on all my basses, so they will never seize up or corrode together.

Be really careful in the design of that tang on the back, and particularly the transition to the tang. The way you have it sketched, it will be very weak right at that corner of the heel. And that's where the bending loads are the highest, because of the long lever arm of the neck. The tang itself needs to be about 1/2" thick, and the transition should be about 3/4" thick at the thinnest point. You can mill away a bunch of aluminum on the inside to keep the weight down, but you need the thickness in the side view to create enough beam strength. The vertical side walls are the structure.

So, the tang will need to be inset partway into the thickness of the body, like 1/2". You'll need to make notches in it to clear the pickups. You can work that out.

This neck is going to be a pretty complex engineering and machining job. If you have the time and machines, go for it!

All good points! Yes the transition point will be more robust. My sketch was more to show the attachment style. also, Ill be only have the single pickup a little closer to the bridge than the traditonal P placement. I dont plan for the tang to extend quite that far.

Whats up with the brass and stainless? Limits the possibility for galvanic corrosion?

 

[Bruce Johnson]

Whats up with the brass and stainless? Limits the possibility for galvanic corrosion?

Brass and steel will not corrode together, even when submerged in salt water. More important, they will not mechanically seize up and gall against each other. Stainless bolts into brass threads is the classic combination in machine design, when you want to make sure the bolt will always come apart in the future.

Stainless bolts into stainless threads are notorious for galling and seizing. Stainless bolts into hardened steel threads (like Heli-coils) is better. Stainless bolts into aluminum threads can seize.

 

[Gilmourisgod]

As a boat owner, I regularly tear my hair out trying to free up stainless bolts either threaded to, or passing through aluminum. Putting a boat into salt water effectively welds these parts together, which the outboard engineers must have fully realized would happen. I remain sceptical that aluminum is anything even remotely approaching the best material for a bass or guitar neck, which does not dimish the coolness of the attempt anyway. I have only one bass that never moves in response to humidity or temprature, never needs any setup related to relief, and will stay in tune for MONTHS: my Steinberger, which has a solid CF/Graphite neck. If there is a better material for a bass neck, I havent seen it. At any rate, you seem determined and undaunted, looking forward to build photos if you care to post them.

 

[ardgedee]

Stainless bolts into stainless threads are notorious for galling and seizing. Stainless bolts into hardened steel threads (like Heli-coils) is better. Stainless bolts into aluminum threads can seize.

This reminds me that old-school bicycle guys have said for years that the best way to secure a screw to a steel frame is to lubricate it. It sounds counterintuitive but oil will minimize the seizing, leaving just enough friction to keep the screw in place. Lock-Tite works but is overkill most of the time, and inserting a screw dry is the same as asking your tech to hate you in five years when you want that fender or rack removed.

 

[Max Bogosity]

I used to work for an aircraft engine manufacturer, and standard practice there was also to lubricate every bolt and screw with engine oil on assembly. It gives a higher and much more consistent clamping load.

And absolutely every thread in aluminum was fitted with a thread insert. If something is going to corrode, much better for it to be a cheap and easily replaceable insert, not an expensive proprietary part.

 

[WilbursaurusRex]

Just as an update. Ive kicked around some ideas but haven't started any CAD work yet. I also had a revelation that has shifted my priorities. In order to get the scale length right (and the dimensioning of the neck itself), I need to define where my bridge is going to mount...and bc im shooting for headless, that has led me down the rabbit hole of self-machined bridge and tuning systems

Im considering doing a 2 pc design like warwick, but instead of having a tailpiece, ill have my tuning mechanism.

Also, I drove over to Aluminati in Asheville, and got to check out some of their instruments. Really cool stuff!

 

[ardgedee]

Im considering doing a 2 pc design like warwick, but instead of having a tailpiece, ill have my tuning mechanism.

For design ideas, take a look at the two-part tailpieces and bridges for headless, from ETS and ABM. Status used to build basses with two-part bridge/tailpiece too. Basslab still uses this type on their headless basses. (Why yes, I am keeping a document offline about headpieces, tuners and bridges for headless basses. )

Some people in Luthier's Corner have built those type for their own projects. Do some searching here and they should pop up, with step-by-step construction details. MPU comes to mind but he's not the only one who's done it.

 

[WilbursaurusRex]

So, here is where the "not a luthier" part comes in. I'm still trying to consider dimensions and how they relate to one another on a musical instrument.

Here are my knowns (but subject to change based on advice/reality):

- 5 strings tuned E to C (16.5mm bridge spacing, not sure on nut width yet. I don't want a ton of taper)

- ~31" scale length

- ideally 24 frets

- using an old peavey patriot body I'll be modifying for the neck and bridge


What do I need to determine next? I know the nut to 12th fret x2 is scale length but that's based off a fretboard I haven't modeled yet. Maybe I need to do that first and take the length dimensions from that, then model the neck around those?

How do you luthiers go about laying out something like this when it's a non fender instrument?

 

[Anthony Fury]

Try this calculator (you can go down the fan fret rabbit hole as well): ekips.org - FretFind2D

 

[ardgedee]

So, here is where the "not a luthier" part comes in. I'm still trying to consider dimensions and how they relate to one another on a musical instrument.

Here are my knowns (but subject to change based on advice/reality):

- 5 strings tuned E to C (16.5mm bridge spacing, not sure on nut width yet. I don't want a ton of taper)

- ~31" scale length

- ideally 24 frets

- using an old peavey patriot body I'll be modifying for the neck and bridge


What do I need to determine next? I know the nut to 12th fret x2 is scale length but that's based off a fretboard I haven't modeled yet. Maybe I need to do that first and take the length dimensions from that, then model the neck around those?

How do you luthiers go about laying out something like this when it's a non fender instrument?

Not a luthier (yet) but I'm currently planning a design by designing a fretboard and string paths on FretFind2D, then taking the PDF it generates and pasting it over a clear square-on photograph of a bass body that I'm using as a design cue.

My impression of the Peavey Patriot is that it's more or less a tweaked version of a Fender Precision body: Horns are skinnier, lower bout has slightly rounder curves, but otherwise the lengths and widths of each should be in the ballpark of each other. Get a big sheet of paper and trace the body onto it, then you have a flat image that you can measure and draw over.

 

[T_Bone_TL]

You should probably peruse this thread https://www.talkbass.com/threads/cnc-fretboard-g-code-generator.1485378/ which has a fairly sophisticated g-gode generator for fretboard stuff with various options.

 

[WilbursaurusRex]

You should probably peruse this thread https://www.talkbass.com/threads/cnc-fretboard-g-code-generator.1485378/ which has a fairly sophisticated g-gode generator for fretboard stuff with various options.

well I know what I'll be checking out today! Thank you!

 

[WilbursaurusRex]

So I've been working away at ideas and one thing I'm trying to be mindful of is taper. I've learned I don't like too much taper.

Bc it's a shorter than standard scale length and I don't want the bridge string spacing to be less than 16.5mm it means the nut width may be chunkier. I drew up a model for the neck (well the first 1/4 of the scale length) with a nut width of 2" and 3d printed it. Just to get an idea. I think I'll probably settle on a 1.875 nut.

btw, how do y'all determine string spacing for a 5 string? Put the 3rd string in the middle at the the top of the FB radius and space the others out from there, which leaves the fretboard edges uneven? Or establish your edges plus midpoint of the string gauge you plan to use and then fit the other 3 strings equally between the high and low string?

 

[T_Bone_TL]

I think most people either have a center-to-center or edge-to-edge (between strings) spacing (and which of those can approach religion in some discussons...) in mind for the strings, and an idea how much they want to have at the outer edges, and make a neck width to suit, rather than working the other way. Particularly with edge-to-edge spacing there's not much odds the middle string will be in the center of the neck. With center-to-center it should be, unless the edge spacing is different on bass and treble sides.

 

[WilbursaurusRex]

Any more takes on the on center or based of fretboard overhang spacing methods?

 

[ardgedee]

Any more takes on the on center or based of fretboard overhang spacing methods?

Have you seen this thread: Question about string spacing at nut

 

[Matt Liebenau]

I figure out how far in from the edge of the fretboard I want the outside strings then match up the lines on the StewMac nut spacing ruler for the right number of strings and mark them out. I believe those are made for equal distance between the strings. Sorry, boring answer.