Twiggy - An EBB5 bass prototype

[SamIAm]

I suspect that 10mm or less would do; I can take slack up in the string mount at the neck.

Design looks good ... but the bits I've got to hand are

 

 I can also 3D print stuff ... and (If Xena plays ball) I may be able to mill the 3mm aluminium I've got. (Think like a metre ruler but without markings lol)

 

It's a bit like doing a puzzle, I keep shifting bits around on the table to see if an idea springs forth.

 

S'manth x

[LukeFRC]

2 hours ago, Si600 said:

 

Elegant tuner on an inelegant back of envelope. 

 

Or...... how much movement does a tuner actually need, could you adapt the fine tuner mechanism on a Floyd Rose style trem to work?

I measured and think the Lefay has 20-25mm travel 

[Random Guitarist]

2 hours ago, 3below said:

Having never owned a headless bass I am interested to know how much tension you need to get on the strings before locking and tuning, and as @Si600asks, how much movement is needed.  Me, I like headstocks, stops my left hand falling off the end of the bass

 

Being bored I attached a pointer made out of a post-it note to the top of my tuner and measured the rotation of the post required to go from pitch to slack. The  E (.105) needed 1/8th of a full rotation, the G (.045) needed 3/16ths.

 

The tuner post is 11.1mm diameter which stirred together I think gives:

 

 

Note 1: This was with TI flats

Note 2: I need to get out more

Edited June 13, 2022 by Random Guitarist
added notes

[3below]

^no need to get out more, plenty of entertainment with engineering mathematics. It is the kind of thing I also do for entertainment, lifelong physicist / engineer here. You have me wondering do you need (b+c)*pi or (b/2+c)*pi, what is the effective diameter causing the length change, however in real world mode, the difference is negligible so I will stop @Smanththread wander. perhaps I need to get out more 🙄

Edited June 13, 2022 by 3below

[Si600]

40 minutes ago, Random Guitarist said:

 

Being bored I attached a pointer made out of a post-it note to the top of my tuner and measured the rotation of the post required to go from pitch to slack. The  E (.105) needed 1/8th of a full rotation, the G (.045) needed 3/16ths.

 

The tuner post is 11.1mm diameter which stirred together I think gives:

 

 

Note 1: This was with TI flats

Note 2: I need to get out more

The E string needs 5.4 mm of travel from slack to pitch? 

[Si600]

1 hour ago, LukeFRC said:

I measured and think the Lefay has 20-25mm travel 

Yeahbbut, how much does it actually need? Could a slight downward movement a la the fine tuners be enough? I've no idea BTW, I'm designing/pontificating on the fly 😉

[Random Guitarist]

15 minutes ago, Si600 said:

The E string needs 5.4 mm of travel from slack to pitch? 

Yes, that appears to be the case. 

[Random Guitarist]

38 minutes ago, 3below said:

^no need to get out more, plenty of entertainment with engineering mathematics. It is the kind of thing I also do for entertainment, lifelong physicist / engineer here. You have me wondering do you need (b+c)*pi or (b/2+c)*pi, what is the effective diameter causing the length change, however in real world mode, the difference is negligible so I will stop @Smanththread wander. perhaps I need to get out more 🙄

Yes I pondered that for a moment. But it is (b+c)/2.

 

I have Post Diameter 'D', String Thickness 'S', and the formula for circumference of a circle C =2 * pi * R

My effective radius is half the diameter plus half the post thickness

R = D / 2 + S/2 which equivalent to  (D+S)/2

From this  C=  2 * pi * (D+S) / 2 

The expressions to mulitply and divide by 2 cancel leaving C = pi * (D + S)

 

 

[3below]

11 hours ago, Random Guitarist said:

Yes I pondered that for a moment. But it is (b+c)/2.

 

I have Post Diameter 'D', String Thickness 'S', and the formula for circumference of a circle C =2 * pi * R

My effective radius is half the diameter plus half the post thickness

R = D / 2 + S/2 which equivalent to  (D+S)/2

From this  C=  2 * pi * (D+S) / 2 

The expressions to mulitply and divide by 2 cancel leaving C = pi * (D + S)

 

 

You are correct , I was thinking in radii, (R + S/2) and diameters at the same time.  With a diagram it became obvious, overall diameters require (D+2S/2) - the string wraps round the post on both sides. 

 

 

 

 

 

 

 

 

 

 

 

Edited June 14, 2022 by 3below

[Si600]

11 hours ago, Random Guitarist said:

Yes, that appears to be the case. 

Hmmmm. That kind of puts the kibosh on nicking the design of a Floyd Rose I think. Downward movement of up to 6 or 7 mm to tension the strings means the tailpiece height is going to be ridiculous.

[SamIAm]

Progressing with Twiggy.

I took her into the makerspace and did some chopping to try to slim down the neck; I'm just going for it!  It will probably turn out badly, but I'll be learning loads.  Aiming for a C profile with a thickness of 18mm at head to 25mm at body end.  I just rasping, shaving, sanding, repeat and feeling/measuring it now and then.  I'm finding it amazingly relaxing; total immersion in the process; the smell of sawdust; loving it!

 

Sadly a crack has developed in the bottom section (body as such) of Twiggy; it does not seem to have compromised the structure much (if at all)  I'm going to try to glue/clamp it and hope it hangs together for a while.  I'm totally prepared to need to set Twiggy aside at some point as having met her intent of providing a platform for me to prototype some stuff, but it would be great if she actually survives and plays ... the sustain I've been getting on trial tune-ups has blown me away and with a lovely grunty growl!

 

The tuners are a nightmare tho, they shift position as I tune and require two hands to stabilise; I can tune up but it is a trial!  I got hold of some Nylon filament (Nylon has one of the higher tensile strength ratings of printable material) and am printing some tuner ball catcher bits, something like these.

 

But with a cylindrical cross section rather than the pictured flat one.  I've recessed the ball hole slightly at the bottom so under tension it should not pop out of the slot.  I'm just going to see by trial and error if they are strong enough to cope with the string tension; I do have a backup plan to add in a couple of thin longitudinal M2 bolts to add strength, the other option is to mill them out of some aluminium rod (But I don't have any to try with at the moment).

 

S'manth x

[crazycloud]

10 minutes ago, Smanth said:

I just rasping, shaving, sanding, repeat and feeling/measuring it now and then.  I'm finding it amazingly relaxing; total immersion in the process; the smell of sawdust; loving it!

Wonderful, isn't it? I won't have music or any other distractions, especially when it's only hand tools.

[3below]

2 hours ago, Smanth said:

Progressing with Twiggy.

I took her into the makerspace and did some chopping to try to slim down the neck; I'm just going for it!  It will probably turn out badly, but I'll be learning loads.  Aiming for a C profile with a thickness of 18mm at head to 25mm at body end.  I just rasping, shaving, sanding, repeat and feeling/measuring it now and then.  I'm finding it amazingly relaxing; total immersion in the process; the smell of sawdust; loving it!

 

Sadly a crack has developed in the bottom section (body as such) of Twiggy; it does not seem to have compromised the structure much (if at all)  I'm going to try to glue/clamp it and hope it hangs together for a while.  I'm totally prepared to need to set Twiggy aside at some point as having met her intent of providing a platform for me to prototype some stuff, but it would be great if she actually survives and plays ... the sustain I've been getting on trial tune-ups has blown me away and with a lovely grunty growl!

 

The tuners are a nightmare tho, they shift position as I tune and require two hands to stabilise; I can tune up but it is a trial!  I got hold of some Nylon filament (Nylon has one of the higher tensile strength ratings of printable material) and am printing some tuner ball catcher bits, something like these.

 

But with a cylindrical cross section rather than the pictured flat one.  I've recessed the ball hole slightly at the bottom so under tension it should not pop out of the slot.  I'm just going to see by trial and error if they are strong enough to cope with the string tension; I do have a backup plan to add in a couple of thin longitudinal M2 bolts to add strength, the other option is to mill them out of some aluminium rod (But I don't have any to try with at the moment).

 

S'manth x

Cylindrical rods will have a tendency to rotate and twist the string as the tension increases. Print cylinders with some flats on the sides so the rotation is stopped by the neighbour.

[SamIAm]

9 hours ago, 3below said:

Cylindrical rods will have a tendency to rotate and twist the string as the tension increases. Print cylinders with some flats on the sides so the rotation is stopped by the neighbour.

You're absolutely right, they do spin; something I can sort when I reprint.

At present they seem to be holding up, I'm pleasantly surprised!

Currently printing knobs to mount on the brass collets.

[Si600]

And? Has anything important gone "Sproink" yet? Is Trampa playing it for you? Is it now an LCD multiscale fretless? Have you given up and called it firewood?

[Richard R]

30 minutes ago, Si600 said:

And? Has anything important gone "Sproink" yet? Is Trampa playing it for you? Is it now an LCD multiscale fretless? Have you given up and called it firewood?

Worst case scenario- Trampa has become sentient and taken over the CNC machine to create an army of killer instruments. S'manth has had to take on Sarah Connor's role and is fighting back with the mantra "There is no bass but what we make".

 

 

Sorry, it's been a long day.

[SamIAm]

The Trampa-nator is not on the loose, Zena is safely quiescent on my desk, Twiggy is far from firewood. (I did laugh at the comments tho!)

 

Things have been progressing.

I reprinted the ball-end holders for the tuners; they now have an extension that sits against the 'body' to prevent them just spinning.

The Nylon filament is well strong enough, but it does tend to 'string' (Hence all the fuzzy bits which I was in too much of a hurry to play and so did not file down).  I also mounted some ball races to cut down on the force required to turn them; it's still not great but it's workable.

 

In the first photo you can see I've also printed strap buttons and a case for the electronics (Well apart from the battery lol), there is an active 3 band tone control + volume in there).

 

I've also printed a new style pup holder, the pup was sitting too high in the body forcing a crazy high action ... it's a fair bit better now.

 

I've settled on a 780mm B0 to 740mm G2 and started to shape the neck accordingly.

 

 

The neck is asymmetric (by choice) and meanders all over reflecting the relaxing just go for it hand crafting (with some one eye closed, tongue poking out, power jigsawing) I've been doing.

I was so chilled, I goofed and did not leave enough space at the edge of the fingerboard so whilst my B0 is just about OK, my G2 tends sneak off the edge.    With an unfinished pine fingerboard I'm not getting the flatness nor hardness of surface that I think I need, so I'm trying to print a fretboard.  I've actually got a 500mm radius on it.  I should be in a position to try it out in the next week or so.

 

So ... S'manth, why have you fitted a strap!?

Twiggy had her first outing to band practice on Tuesday ... the reception was warm!  OMG that's amazing was repeated a few times.

We are not in the habit of taking a photo at practice, this was our first time all together, our new lineup, where everyone remembered to bring their "shirt"; some 'photoshopping' to be done before they go on the web site, but you can see Twiggy!

 

To be honest, I need to do a lot more practice with her.  The longer scale length than I am used to, the fact she has 5 strings, her being multi-scale and fretless ... all new and different for me, but I'm enjoying the journey!  And she sounded pretty good!

 

We've our first "performance" in a couple of weeks (We are playing to entertain (hopefully) the folks who will be taking part in the Worthing Pride march whilst they are getting organised) ... I am hopeful Twiggy will make her first public appearance there

 

Once I've got the fretboard printed and on I'll try to get a recording to share.

 

S'manth x

  

 

 

Edited June 23, 2022 by Smanth
Minor typo correction

[Richard R]

Very impressive!

I'm surprised that the printed components have the required strength. Most of what I've seen printed has next to no strength and certainly wouldn't hold anything under tension. 

[Si600]

It lives!

 

It's an interesting looking beastie certainly

 

Given that you don't have a trussrod do you forsee a time when you end up with a banana or are you going to leave Twiggy thick enough not to need one? How playable is a neck that thick?

[SamIAm]

With Twiggy's asymmetric, thin, non reinforced pine neck I suspect that it will not be long before physics start to come into play and I get unwanted twist.  I'm toying with routing out a channel to drop in a dual action truss rod, but will that help with any twist I might get?

I've been surprised how much I like the feel of the fretless neck, so Flo is likely to have the same.  But this time a more considered neck profile, with internal supports and truss rod.

If I were to craft Flo from a single piece of wood ... which wood should I go for?

Or is it a better design to go for a through body neck made from a different piece/kind of wood?  With the equipment I have available at the maker space I've joined I will be able to plane/fit/joint wood and I've the clamps & space to assemble them.  If I go this route, what recommendations for neck wood/body wood?  I think I will got for a dark fingerboard (either stained wood or 3D printed if it works well on Twiggy) but I love the idea of the natural wood of the body showing with a protective oil (or similar) finish to give her a nice satin sheen.

 

I feel that Twiggy is short enough for me not to have to try out the pulley system I was thinking of, tho it would allow me to hide the tuners on the rear leading to a really minimalistic look from the front.  My plan for Flo is that the electronics will live in body cavities, the knobs for such will present on the top edge and be hidden (From the front view at least) by a recess.

 

S'manth x

 

 

[SamIAm]

11 minutes ago, Richard R said:

Very impressive!

I'm surprised that the printed components have the required strength. Most of what I've seen printed has next to no strength and certainly wouldn't hold anything under tension. 

I was very surprised also.  I went for Nylon filament (Overture Easy Print Nylon to be exact) as I gather Nylon has the second highest tensile strength of 'conventional' £d filament and I printed the parts on the large side ... touch wood they seem to be holding with no ominous cracking or even creaking!  I printed at 0.15mm layer height.

[SamIAm]

13 minutes ago, Si600 said:

It lives!

 

It's an interesting looking beastie certainly

 

Given that you don't have a trussrod do you forsee a time when you end up with a banana or are you going to leave Twiggy thick enough not to need one? How playable is a neck that thick?

The neck is thin on the treble side and thicker on the bass side and feels pretty good from a playability perspective.  As you say I need to either expect a limited neck life or add in some beefiness, the latter seems most likely for sentimental reasons as well as giving me experience of another technique that I can learn from and apply to Flo.

[Si600]

43 minutes ago, Smanth said:

I feel that Twiggy is short enough for me not to have to try out the pulley system I was thinking of, tho it would allow me to hide the tuners on the rear leading to a really minimalistic look from the front.  My plan for Flo is that the electronics will live in body cavities, the knobs for such will present on the top edge and be hidden (From the front view at least) by a recess.

 

S'manth x

If you haven't already, check out Mr. Jr1515s thread on how to hide almost everything behind the body. Psilos is the name of the bass.

[Frank Blank]

I must refrain from swearing but that is f****** amazing.

[3below]

To my take, the ultimate anti twist and relief solution would be two truss rods (I could be totally wrong).  Whether this is necessary rather depends on the tensions of the different strings.  Choice of woods is almost a religious matter, balsa is probably unsuitable Something hard and wear resistant for the fretboard. Ebony, Katalox, Ipe spring to mind or one of the synthetic / semi synthetic alternatives- rocklite, richlite.

Edited June 23, 2022 by 3below