3D Printed Bass with Aluminum Backbone

[GisserD]

I have never built a bass before, but I recenlty acquired a bass neck and i intend to build a bass around it. The neck is 35in scale 5 string. ebody board with compound radius, and 24 frets. string spacing at the bridge will be 17.5mm

The intention is to build a bass body from a 8 or 10mm aluminium plate, sandwiched between 2 3D printed slabs made from ABS. The idea being that the neck and the bridge will be directly mounted to the aluminium creating stifness.  Ill be putting nordstrand blade in the neck and nordstrand blademan in the bridge with john east preamp.

Theres some scheme drawings below to give you an idea of design. The neck has been scanned and loosely modeled. bridge chucked on for ilustration purposes.

Id welcome any feedback from the more experienced builders if youd care to give it. Particularly if you have experience with metal or 3D printed guitars.

ill keep this thread wpdated with progress for those interested.

 

 

 

 

Edited November 11, 2019 by GisserD

[MoonBassAlpha]

Might be worth considering minimising the use of aluminium to the structural areas as it might turn out rather weighty. 

[Si600]

@Andyjr1515 is the man to talk to about how much structure you actually need, he's accidentally built a bass out of something with no structural value once and deliberately a second time.

Interesting concept you have though, like it.

Edited November 11, 2019 by Si600

[GisserD]

7 minutes ago, MoonBassAlpha said:

Might be worth considering minimising the use of aluminium to the structural areas as it might turn out rather weighty. 

the currently modelled ALU plate is 8mm and weighs in at 2.3kgs which is about what id be shooting at for total body weight. so once ive removed material for electronics cavity, holes for mounting etc, i dont expect to be too far off as the plastic part will be roughly 0.7kgs.

Regardless, i can tune the mass of the bass by either making the backbone thicker, or cutting holes in it.

 

Edited November 11, 2019 by GisserD

[sprocketflup]

Don't forget wiring holes/routes!

[verb]

Flat metal plate may flex under string tension, strips of metal positioned to form a T with the main plate would help reduce this.Think of an RSJ. 

[GisserD]

9 minutes ago, sprocketflup said:

Don't forget wiring holes/routes!

thanks i wont  i literally strted drawing this today so still loads of work to be done!

[Andyjr1515]

12 minutes ago, Si600 said:

@Andyjr1515 is the man to talk to about how much structure you actually need, he's accidentally built a bass out of something with no structural value once and deliberately a second time.

Interesting concept you have though, like it.

No experience in either metal guitars (although I did used to be in the aluminium industry) or ABS, @GisserD , but, from a strength point of view, this would be more than strong enough.  Significantly so. 

With this type of sandwich, as long as you could stop the ABS / Ali laminations sliding across each other and allowing the whole structure to bend, 3mm aluminium sheet or even thinner would, I suspect, be more than adequate.  Are we talking pure aluminium or an alloy?  Worth bearing in mind that the body and wingskin of a modern airliner is less than 2mm.

I also would have thought that this would be exceedingly heavy, but if your CAD says that for the finished body, then presumably it's going to be there or thereabouts.  I don't know what the strength of ABS is compared with, say, nylon, but I suspect that alone would be strong enough.  All you need, to be honest, is enough rigidity between the neck joint and the bridge (and a decent way of firmly fixing the two to the body) and the rest is just a convenient place to hang the pickups and controls.

Fascinating - watching with interest

 

 

[GisserD]

thanks for your input @Andyjr1515

i actually want the bass to look and feel like a "normal" bass eventually. Once i proved out the concept, and everything is working playing correctly, i will bond, filler and paint the body like any other. With that in mind the aluminium actually serves another purpose of distributing the mass throughout the body. This is to avoid the bass "feeling" odd. For example if you were to pick it up by the upper horn. 

I antisipate many fixings across the "sandwich" eliminating the posibility of any sliding betrween the layers (especially once glued). The ABS components are intended to be an integral part of the design, not just a beauty cover over a minimal metal guitar body. The sandwhich construction will go a long wat to achieving what is effectively a composite. The 2 materials resonating at 2 very different frequencies effectively dampen eachother.

Yes aluminium alloy, probably 6082 as my local cutting shop keeps a stock.

I have seen bass/guitar bodies entirely made of 3D printed polymers, so i know its feisable..... But the Engineer in me is saying its not stiff enough. Hense the additional metal in my design. The main reason for using ABS over PLA is its resistanceto impact. Than and that it can be chemically smothed/bonded to itself with acetone which may come in handy later in the project.

 

Great to have you on board!

Edited November 11, 2019 by GisserD

[TheGreek]

Inevitably (surprised nobody else beat me to it TBH)

Do you think it will be any good for...........

[itu]

If ABS is soft, use some PA with 40 - 60 % GF and it certainly will not bend. I used to be in a company that produced plastic things out of PA with lots of GF. Those ones with high fiber content tend to sound like glass.

Of course you can consider some wave, or box like shape to the plate and make it far more tough to bend. Italian alusonic produces basses with (partial) aluminum body.

[GisserD]

10 hours ago, itu said:

If ABS is soft, use some PA with 40 - 60 % GF and it certainly will not bend. I used to be in a company that produced plastic things out of PA with lots of GF. Those ones with high fiber content tend to sound like glass.

Of course you can consider some wave, or box like shape to the plate and make it far more tough to bend. Italian alusonic produces basses with (partial) aluminum body.

is ABS considered soft? hardness is usually corelated with flexural modulus (stifness)

Glass/carbon filled nylons are really only common on SLS printers. I only have FDM which limits me to PC, PP, Nylon, PLA, ABS and CPE.

Glass/carbon Filled nylon is available as an FDM material choice but its hard to print with and ebrasive on the feeders and nozzles and i just dont feel its necessary.

Edited November 12, 2019 by GisserD

[itu]

1 hour ago, GisserD said:

is ABS considered soft?

Glass/carbon filled nylons are really only common on SLS printers. I only have...

No sir, I just added a material option. As your system is FDM, ABS is certainly fine.

[Si600]

I've not traveled by plane with a bass so I don't know what the process is, but it would be interesting to say the least if it got x-rayed and all they could see was a black bass body shape on the screen. No idea how you'd prove it wasn't hollow and filled with Columbian marching powder (to contaminate this thread with the Den of Iniquity one 😉)

[Matt P]

As you are planning to smooth and paint this body i would be tempted to reduce the amount of aluminium to a minimum, you only really need the high strength round the centre to counteract the string tension, the outer areas could have a much thinner skin of only 1 to 1.5mm, with a thicker central area for the bridge etc, i'd suggest some kind of bonded in threaded metal insert to take the strap buttons as well.

if this was my project i would be tempted to go for a clear coat finish to show off the construction methods! a brushed or polished finish on the aluminium parts with the printed section visible at the edges could look really striking.

 

the only thing that i would be wary of is the thermal expansion of aluminium, i seem to remember that alu necked basses were a thing at one point and they had tuning difficulties if the temperature was not stable (under hot stage lights or coming in from a cold journey) this might cause bonding issues between the aluminium and the printed parts or tuning issues. it might be worth making a small test part to check (simple printed block bonded to a small sheet of aluminium. then try warming and cooling it to see how it holds up. it would be embarrassing to have the body split or crack after all the work.

I should say that i am a mechanical design engineer by day so my first reaction is usually to look for the areas that would cause a product to fail (i spent a long time designing access platforms for offshore use and they get a little shirty if people fall through them into the sea)  but a little bit of experimentation before launching into the project could save you from making an expensive paperweight.

 

Matt 

[GisserD]

20 minutes ago, Matt P said:

As you are planning to smooth and paint this body i would be tempted to reduce the amount of aluminium to a minimum, you only really need the high strength round the centre to counteract the string tension, the outer areas could have a much thinner skin of only 1 to 1.5mm, with a thicker central area for the bridge etc, i'd suggest some kind of bonded in threaded metal insert to take the strap buttons as well.

if this was my project i would be tempted to go for a clear coat finish to show off the construction methods! a brushed or polished finish on the aluminium parts with the printed section visible at the edges could look really striking.

 

the only thing that i would be wary of is the thermal expansion of aluminium, i seem to remember that alu necked basses were a thing at one point and they had tuning difficulties if the temperature was not stable (under hot stage lights or coming in from a cold journey) this might cause bonding issues between the aluminium and the printed parts or tuning issues. it might be worth making a small test part to check (simple printed block bonded to a small sheet of aluminium. then try warming and cooling it to see how it holds up. it would be embarrassing to have the body split or crack after all the work.

I should say that i am a mechanical design engineer by day so my first reaction is usually to look for the areas that would cause a product to fail (i spent a long time designing access platforms for offshore use and they get a little shirty if people fall through them into the sea)  but a little bit of experimentation before launching into the project could save you from making an expensive paperweight.

 

Matt 

The great thing about constant thickness aluminium is that it dosent need machining. I dont have access to a mill, and prefer to keep all the manufacture in house (my actual house)the only part ill be ordering is the ALU plate itself waterjet cut from a local supplier that i know and trust.

I intend to drill and tap into the aluminium for the strap buttons. This way the load will all be taken through the backbone.

The body will likley have to be printed in 4 or more pieces, and im thinking about dovetalling the pieces together, which may look nice, it may not. It will all be in the development. if it looks attractive then i may choose a clear as you suggest. I had assumed that the edge of the aluminium will be unattractive but i like your suggestion about leaving it exposed, ill give that some thaught thanks.

The body will be designed to function without glue. The glue process at the end will only be once i have valitated the design and this will help the body become more momodgeneous and remove any vibration between parts/fill gaps. Id likley use an adhesive that can take up any movement if there is any. But over a length so small (400mm) and the temperature differential its likley to see, im not really that concerened as any sheer loads would be incredibly small.

 

 

[Matt P]

i must apologise, I managed to get your plans all back to front! in my head you were planing a printed core with front and back plates of aluminium.

the solid core plan is much more robust, and a single thickness through the body will certainly give a good solid foundation for everything to mount to, i'd probably go for some lightening holes in the alu plate as it would be much easier to add some mass back in than try and remove the material at home.

i would still suggest that testing the adhesives on a small scale and under fluctuating temperatures would be worthwhile as the embarrassment of part of your bass falling off on stage would be pretty high, also having used a 3d printer i know how long it actually takes to get a print out (even ignoring the fact that there is a fairly high failure rate with 3d printing) having a part that took hours to print fall off and get damaged would not be ideal. the thermal co-efficients of aluminium and ABS are quite different so the testing should show up any issues that might occur.

If you can design the whole thing to work without glue then that will work much better but i would still make allowances for the different rates of expansion of the materials and the vibration of the whole instrument will be subjected to.

i look forward to the first parts being made! 

Matt

[HazBeen]

Alusonic use solid aircraft alloy bodies, do not think overly weighty.

Great idea! 

http://www.alusonic.com/aluminium-bass-django-supreme4.php

[Owen]

I would love to contribute to this thread in a meaningful way. But I cannot. But I will say YES! Very cool. 

[Hanry]

...as for the airport scanners, just rotating it by 90 degrees should do the trick? 😉

[honza992]

On 13/11/2019 at 18:34, owen said:

I would love to contribute to this thread in a meaningful way. But I cannot. But I will say YES! Very cool. 

Yep, this.  Lots of skills and knowledge which I really wish I had!  Really looking forward to this one....

[GisserD]

Thanks to all those who have commented, it's great to have you on board.

Super busy with work this week but I'm hoping I might get a couple of days to iron out some details next week. 

I'm seriously contemplating putting the pickups in shuttles that can be moved along the strings at will. Find that sweet spot!

[SpondonBassed]

23 hours ago, GisserD said:

I'm seriously contemplating putting the pickups in shuttles that can be moved along the strings at will. Find that sweet spot!

Like Westone's The Rail eh?  Nice.

[GisserD]

1 hour ago, SpondonBassed said:

Like Westone's The Rail eh?  Nice.

Yes but, because the components will be 3D printed, I'll find the sweet spot then re-print the core (centre front) to fix those positions on the final guitar. 

 

[SpondonBassed]

12 hours ago, GisserD said:

Yes but, because the components will be 3D printed, I'll find the sweet spot then re-print the core (centre front) to fix those positions on the final guitar. 

 

I get you.  The first build being a test bed for the prototype.  Good thinking.