help {plz!} neck back shape, bongo specs, and translating it for CAD

[CRTL+ALT+DEL]

[CRTL+ALT+DEL]

mad scientist
May 25, 2008
201
23
4,551
Brooklyn
#1
hello,

I was building a bass. for various reasons, halfway through, and then i decided to go looking for some help. i'm trying to get a bunch of work done through a fab shop. and turn my half built bass into more of a "bass kit", that i can feel more confident about finishing.

i'm compiling all my notes for the guy who is going to turn it into cad and put it through some cnc.

i got to the part about the back of the neck shape. i originally was going to do it by hand, decided against it. was going to have a real luthier do it but, long story short....

i'm compiling info for the fab shop, who prolly knows nothing about this subject. i want to figure out how to tell them the specs to make the back of the neck shape or contour. it's more of an oval shape than a circle for your average shape neck, right? i'm looking for a middle of the road shape. or if someone has the specs on a bongo 5 string, i would love to figure out how to get that neck back shape. i'm i just too tired and over thinking this? is it just that this project has collected dust and i lost a note, or my mind? lol.

i've been scouring around for hours here and on google. i have all the other specs to do with the neck; nut width, neck thickness, etc. just trying to figure out to get the measurements to give the cad guy to get the right neck back shape.

thanks
tb friends
 
#2
IMO, ultimately you'd provide the shop with a Class A surface of you neck's rear contour that extends well past where it intersects the fretboard. The fab shop would then utilize this surface for defining their tooling and tooling paths.

The exact contour of this surface is where the skill of the Luthier morphs with the skill of the CAD designer. The possibilities of the exact contour curves are endless, and subject to personal preferences.

In it's simplest form, the rear profile of a J-style bass is very similar to a C at the first fret and is stretched as the neck widens and deepens on its way towards the body.
 
#3
thanks for the reply. sorry i didn't provide enough info, i was trying to keep it brief. for starters, i am making a super long scale neck through bass.

i've customized many a guitar/bass, but this is my first build. originally my plan was to do everything my self. between my day job taking over my life, my inexperience as a builder and the fact that the woodshop i had a membership too always had mechanical issues with the "publicly" used tools, i decided to bring in outside help. i talked to almost all the luthiers in the nyc area. most said they wanted nothing to do with my project regardless of what i was willing to pay. one guy told me to get with a fab shop. which is where i am now. putting together all my specs in a coherent way for someone who isnt a luthier but a cad/cnc shop. also, i don't have, or have access to any basses but the cheap highly customized basses i own.

many of the specs i am using are based on a bongo, because i always wanted one of those. of course many elements have nothing to do with a bongo. i don't care if it's exact. i'm looking for a middle of the road neck back profile. preferably a bongo, but it doesn't have to be. does anyone know the shape of a bongo neck back profile for a 5er? maybe i should go p/j bass since that is what most people are used too?
 
  • Like
Reactions: saved
#5
do you have the list of details that the fab shop requires from you to take on your project? what level of detail have they asked for on reference info like drawings, CAD model(s), parts to replicate, tolerances, etc ... should all have been quantified and qualified by the shop so you know exactly what they need to make your parts.

when all is said and done, it will be these references that they will hold all parties accountable to for end product and $$$
 
#6
earlysecond said:
Can i somehow assist?
Click to expand...

that would be perfect. i love talkbass. i will make it back to all of you in my own way later on.

the measurements don't have to be perfect. no two basses are the same from hand sanding anyways.

this bass project sat on the shelf for months. so there are a few things i'm re-figuring out. so you could help me out a lot.

if you had a pair of mics and could give me the following:

fingerboard thickness at the highest point, i know they use a 11" radius

for neck width mine is 1 and 3/4 at the nut ~2.18" at the 12th fret ~2.39x" at the 24th fret (those last 2 measurements are me measuring sizes from my blueprint, that i know were right, but i didn't keep great notes, which i kicking myself for now)

for the thickness at the nut(minus the actual nut or fb) is .593" and neck minus fretboard at the 12th is 1.03" and @24th fret 1.26" this would be interesting to see if these # are similar to yours.

the real question would be to figure out the compound radius of the back of the neck.
 
#7
CRTL-

I have V. Calipers, which are digital. I am not skilled in reading mics anyway

1, The fingerboard is installed on the neck so I cannot tell you the max thickness. If you have a properly cut-non compound radius then the most wood is cut from the 10th fret on. I am new to this but it is a recent observation as I have begun to cut, yes cut as in a router fixture vs. sand the Leo Fender way (Fender used a giant belt sander with a top fixture)
2. I can get you the width now:
  • 1.78" at the nut
  • 2.47" at the 12th
  • 2.82" at the 24th

5 String with 15 mm string to string center spacing (gaps are uneven)

3.Again, since the fretboard is on an the guitar is strung . . . . I have no idea how to give the measurements you are hunting. Can you think of a way to measure this without removing the strings and with calipers? I am struggling to find something that will work AND be accurate,

I actually think that I can capture you the neck profile, but doubt it is going to be helpful. If I can find it, my contour gauge would take the shape I could then trace it on paper and take a picture or scan to scale. If you are looking for CAD measurements, you would have to translate that on your own. I am more of a route, shinto rasp, file, check profile and sand type of neck builder! haha

I would not be able to capture the profile until tomorrow as I am in the middle of other things.

AGAIN, this is a kit and I am taking measurements with digital calipers- - - -even the fretboard width is SO drastically different that what you posted that I already have some concerns that what I have is not what you seek!

Hope this helps in any way. If you figure out a way for me to get better measurements, without removing the strings or the fretboard . . .. haha let me know.

Finally I will tell you that the neck on this bass is my SINGLE most favorite, it just feels right to me and I have copied to an extent to other necks. It is very slim compared to a Fender C profile. Much more a flattend D shape vs. a C shape. It is really nice. I am NOT sure it is accurate to the MM design though!
Regards,
Brent
 
#8
thank you very much. my design is bit different, starting with it's a 4 string with 42" scale. but ultimately, i'm really trying to get some of the specs to be a modified version of a bongo 5. i'll go into the method of my madness once i have this thing finished and tested.

so thanks again. this is all very useful.
can anyone with a factory bongo confirm or deny what earlysecond is saying with some of these measurements? it is more of a modern flat d shape, correct? the functional specs of a bongo is what i'm after, if they made them in suuuuppppeerr long scale, i would have just bought a stealth black HH w/peizo and saved myself the headache and the $$$$s i've spent on the wild ride i'm on now. although, once i'm finished i will have the bass i've been gassing for since i was a wee lad
 
#9
are there any cad knowledged luthiers who could give me a cross section of a flat-ish d shaped neck profile from your already designed bass neck? i know that's a lot to ask. but it would be great. something that compares to a bongo 5 neck, or even better is a bongo five exact copy. like a slice from the 1st and 12th fret. i started learning cad, and intend on becoming proficient eventually. but this would help me out tremendously until then. i'm trying to get as much as i can done before i go back to work in a few weeks, which means another 10 months of hell, and not getting much done on anything i care about
 
#10
What I would do is look for a local 3D scanning / printing shop. A quick google search pulled up about a dozen in Brooklyn.

Buy a used Bongo from Guitar Center. Take the bass to the shop that you have selected, have them scan it and then keep the bass, return it to GC or sell it privately.

Since this is not a commercial project, I don't think there is any issues with "counterfeiting" the neck.
The grey area for me is whether using GC for this purpose is ethical. Better solution is find a Bongo on loan locally from a friend or acquaintance.

I think @Joe Nerve has or had one, but you'd better reach out fast because he is quitting TB and selling all of his basses ;)
 
#11
Pure sacrilege! What sell all his basses and then quit here. I hope he is doing that because it is simply time to do something else!

CTRL- Sorry I could not help more than I did. I understood you to say you were building a 5 string. BTW- please take a minute to check out my kit build called Iced Bongo #5.

I have to say that just based on my bongo kit which may or may not be accurate and the passive, overseas pickups. . .I am more than motivated to make my own version with HH and the "correct" electronics. I think it would be a total riot to build one with some really pretty wood. . . radical horn lines and all. I would want another 5 string. It would be a fairly expensive build and I have just sat here and decided NOT to build it from oak or ash. That bass in basswood is VERY heavy. It IS well balanced but it is, by far and away the heaviest of the 7 basses I have, most of which were kits or refinishes of cheap stuff.

I understand your desire to make a modified bongo. I am willing to help any way that I can and might as you to return the favor when you nail it!

One final thought, which is more a a disclaimer. . . .I am very green on basses, building and terms. PLEASE do not accept my description of the neck profile as technically accurate! I will say that I LOVE it though. Enough to use it tomorrow as I put the final finishes on my current neck build which currently is hardly wide enough to accommodate a 1.5 inch nut. . .read skinny and it might as well be thin too!
 
Last edited:
#12
thanks, fellas, i think charlie gave me the best idea yet. as far as i see guitar center rents, as well as a bunch of other places in nyc. the fab shop i plan to use has a scanner. they have a bunch of fun toys like a 3d cnc robot arm mill thing. http://timburllc.com/ hopefully i will be able to report back with some things finally completed soon. and this is a prototype for a commercial venture. although i'm just taking some specs as a guide, my design looks entirely different and is not a standard bass in any way. i will show pics and complete specs as soon as i'm done.
 
You must log in or register to reply here.
Top Bottom
Back