Build yr own bean - I figure, why not?

[Terry McInturff]

Actually the Bean necks, including the fretboard, were turned at the same time making it a seamless contour. Perhaps very early versions were glued after turning, but most of them were done at once. This is directly from the main machinist. I was really surprised that the rosewood didnt chip, but he said that rarely happened. Id assume it was because 2 necks were sandwiched together and spun at the same time.

They were all zero radius until the end of production and then they introduced an slight radius.

They also went to a 2 pc fretboard because of delamination of earlier versions.

Very cool information, thank you!
My Bean did have a "step" at the neck/fretboard joint...must have been an early one.
I do believe that there was no radius too, but I am working from memory.

I worked on a batch of around ten for Bill Kaman back around 1993. He has/had quite a few. I regret that my notes have been lost.

I suppose that my only Q is why a 2 pc fretboard would have any effect at all regarding de-lamination probs. Am I correct in guessing that you are referring to the fretboard/neck glue joint failing???

One thing that I did dig were those big covered humbuckers. To me they tonally resembled the big Fender 'buckers as found on those '70's Tele Deluxe's etc.

All in all the original Bean...the big double-cut with the Koa...was a kick-ass sounding guitar. Great to see them discussed here.

[skinny honkie]

1) The Bean necks were turned on a lathe and therefor the shape of the back of the neck is always a section of a circle.

2) The all-important side of the fretboard was always rather square as opposed to rolled-over. This is because the fretboard was epoxied to the completely shaped neck shaft. There never seemed to be any sort of teased-in blended transition. In fact, due to the mfg process, if the fretboard did not match the width of thew neck shaft, there would sometimes be a very small "step" at the glue-joint transition.

3) The fretboard thickness was rather thin..from memory I'd guess that on average it was 3/16" at the crown on a good day, often thinner. The reveal at the edge was usually just enough to keep the side-dots from breaking thru the top...I'll guess that it averaged .125

4) Again working from memory, the fretboard radius was really big, almost flat. Im guessing a 16-18 inch radius...really flat feeling.

5) Again working from memory, I'd GUESS that the total neck thickness specs would be around the following:
1st fret: around .825
10th fret: around .950

Very interesting Terry. This puts it loosely in the ballpark of my TC90 (.866 from 2nd fret to 14th), I was expecting thinner, and cylindrical rather than tapered. Thanks for clearing up my misconceptions!

Kevin, I know that your necks are routed out - in terms of profile are they based on the bean necks? How deep are the two channels that you take out? I'm not trying to rip off trade secrets or anything - I'm just trying to get an accurate idea of how much metal I can take off the neck (to prevent the headstock diving towards the floor) without compromising it's relief appreciably if I switch between DGCFAD and F#BEAC#F# for example.

[Terry McInturff]

Please remember that Im working totally from memory as regars all things Bean. All told, Ive only worked on at most 30 over a 32 year career!

As far as body balance goes...remember that if you think that your design may get neck-heavy...to be avoided at all costs!....design the body so that the upper strap button will be as far towards the nut as possible.

If you can offset the body so as to make the strap button closer to the nut...whilst retaining a pleasing design and good upper fret access...sometimes an inch closer to the nut (as regards the upper strap button location) will make a big difference as regards the balance on the strap.

[gse]

Heres some approximate measurements I took from a friends tb1000 ( its in the 1700 s/n)
Width at nut. 41.5mm
thichness at nut 21mm
radius 20.5mm

width at 22nd fret 53.5mm
thickness at 22nd fret 25mm
radius at 22nd fret = 26.8mm

divide measurements by 25.4 if you want the imperial equivilents

If you know the exact widths and thickness you want use this site to work out radii
http://www.1728.com/circsect.htm

[gse]

Dont take those measurements as gospel. Im sure Kevin at EGC may be able to confirm if these dimensions are close or correct. Next time I get a chance Ill check the 1000 again

[scott]

Unless I'm not understanding it right, your radius measurements are crazy. The radius should be more like 15 times the thickness, more than that even, as opposed to being roughly equal to it, shouldn't it? If the thickness and radius are equal, that would mean the fretboard is as rounded as the *back* of a normal guitar neck is at the nut!

Hang on, when you say "radius", are you describing the neck profile, or the fretboard radius? Now I'm thinking you're probably describing the neck profile, which makes a lot more sense!

[ptay]

Hang on, when you say "radius", are you describing the neck profile, or the fretboard radius? Now I'm thinking you're probably describing the neck profile, which makes a lot more sense!

The radius is mathed out by taking three points you know: the point where the fingerboard attaches to the metal on either side (2) and the point on the back of the neck exactly at the centerline and at the thickness. You figure out a circle that hits those three points, and the radius comes with it.

An easy example would be a nut width of 1-1/2" and a material thickness (excluding fingerboard) or 3/4". The radius is 3/4" ... if the thickness is thinner, the radius gets slightly longer.

Since the neck tapers, disagreeable as i may be, the radius at the heel is bigger than at the nut.

Old lathes usually only have a 12" tapering length so I don't know how Travis Bean did what I've describe, though they must have. Maybe in sections? ... good question for the resident master.

All this is relatively moot if you're casting the neck, since you can have any profile you desire. Turning necks is an old production technique that I know Martin used, not sure if they started it. Funny too, because it was intended as a mass production technique -- funny old Martins and Beans are far from any association with mass production now!

[skinny honkie]

Cheers GSE! They look very close to Terry's numbers - I'll consider those my baseline.

[scott]

I dunno ptay... pretty sure the way to measure a fretboard radius is to take a length of string of the desired radius, tack down one end, and swing the other end around it in a circle (with a pen) and draw an arc. That arc corresponds to the fretboard contour you'd get for the given radius. To reverse-engineer a fretboard, you'd have to try drawing various arcs and see which one matched.

If you look at numbers you'd find on the net, fretboard radii are usually things like 9", 14", 15", etc. A Travis Bean, with its flat fretboard, would have a corresponding radius of infinity, which is not a real radius, but a flat fretboard doesn't have a radius; it's flat.

If you look at the measured numbers above, 20-something millimeters is less than an inch, and that's just not a realistic fretboard radius. The fretboard would be curved like a thick broom handle. For a neck profile, though, it's possible. But profiles aren't usually refered to as having a radius, even though they're essentially an arc in many cases; they have a "profile" or "contour", which is often described as "C" or "V" or "U" or whatever, indicating what the shape roughly corresponds to.

[ptay]

Scott,

we're totally in agreement. if the back is radiused, it'd be somewhere between a 3/4" and 1-3/4" radius, where if the finger board radius would be 10 to infinity inches.

To reverse-engineer a fretboard, you'd have to try drawing various arcs and see which one matched.

you can also use the thickness of the fingerboard, it's width, the height of the sidewalls above the metal and do a little trig/geo. to get the radius ... or use templates. When it's reasonable to measure down to a thou, the math method is pretty foolproof.

If you actually want to turn a metl neck, do the math for back radius the same way, but add 0.025 to the point where your tool contacts metal on the final cuts so that it isn't hitting the fingerboard-glue-surface ... which would result in a positive rake hitting a positive rake--meaning your tool will dive, the neck will dive and the neck will be toast.

Speaking of deflection, bolting two necks together ... say on tapered steel spit, the way limmyjames said they did it at the factory ... would go a long waay to stabilizing the long and flexible (hard to machine) neck.

[gse]

I should have been more clear
The thicnesses I described include the fretboard, and the radii are refering to the neck profile, not fretboard.

I might try to make a couple of necks at once as JJ6 described). the one I made, whilst it sounds great is quite chunky and hard to play ( i didnt have the measurements ive described when i made mine)
Thinking of making a lathe for this purpose as I havent been able to find one with large enough centers for less than 3 or 4 grand (aus)
Does anyone have an idea of what type and speed motor I should use

[ptay]

Thinking of making a lathe for this purpose

For turning wood or aluminum? I've seen wood turned on a metal lathe, and I've turned aluminum on a shop-built wood lathe.

Does anyone have an idea of what type and speed motor I should use

Depends on whether you'll have one neck or two on the machine at once. If it's only one, you're lathe needs to turn really slow, since it's an unbalanced load, and even a 1200-1500 lb. machine won't stabilize it going much over 100 RPM.

But! It's not the speed you are worried about at first, but the work-holding. You have to have this figured out or your parts will be a huge chattery mess since the neck (even splinted onto a holder) will flex a lot.

Id assume it was because 2 necks were sandwiched together and spun at the same time.

Did you ever hear how they mounted the necks in the lathe?

[chris jury]

I've fussing w/ this off and on for the past couple weeks. Finally found a foundry in seattle that seems interested in working w/ me (a few others said they'd do it, but basically spent the whole time telling me it wouldn't work, or that they wanted to do more than a few pieces to start with).

So I'm going to take my rough pattern down and meet w/ their pattern maker, he'll give me advice, let me know which process will be best (I guess there is a flask-less system that they prefer, and it might work for me), and get me an accurate quote. Should be fun.

I have learned 2 things making this pattern:
1-use alder. it works easy, doesn't chip out -totally worth the $8 I spent on the board

2-use a router - I have this great old hoof rasp, which can remove a lot of material, but a router is way better to start with. You can thin certain parts down to an accurate thickness, and a chamfering bit removes a lot of the material on the sides of the neck before you start w/ the rasp. Probably saved me an hour.

A friend who engineers those stupid 200' yachts is gonna give me a hand w/ CAD to look at machining a couple.

-this has been a fun exercise so far.

[skinny honkie]

Nice one Chris.
I'm still plugging away at my pattern - the kwila wood I'm using is incredibly hard, but amazing stuff - it buffs up like marble with a bit of elbow grease. I'm taking it very slow because I'm waiting to spend some quality time in my uncles garage, he gets back from aussie very soon.
In related news, I called a few hardware shops around town to get a price on a spokeshave (for roughing out the neck) - I couldn't get one anywhere. A couple of the places even said "A what?" I was pretty gobsmacked. I've routed the neck to the side and top-down profiles, leaving a rectangular neck profile thus far. I can rout a rough round profile out, but I'd rather use a bladed tool like a spokeshave, it just feels more right to me. After that I'm going to run a sanding block with a cutout matching the profile I want over it, until its all purty.
Good luck Chris. Keep us posted.

[skinny honkie]

This thread is useless without pictures. Here's where I'm at thus far:


Looking from the nut toward the body -



Quality control is interested in the tassel on the camera -



Strictly side-on shot:



No peeps at the headstock yet. There's a small knuckle down by the nut which fits my hands perfectly - I can slide down to 1st position and no matter what, my hand knows where the frets are. I'll show more of that later. I have left a lot of meat in the pattern so far, as you can tell from the last shot - the edge of the heel correspond to where the 22nd fret will be. The neck is 21mm (0.826") thick at the 2nd fret, 22mm (0.866") at the 12th. I think it would be called a "U" profile neck in neck-nerd terms, certainly it's non-circular. I have left a bit of draft in it for the foundryman, and it feels really lovely to my hands..

[ptay]

Don't forget to make it oversized ... forgot to mention that! Aluminum shrinks when it cools!

That think looks awesome. Nice oily wood too from the looks of it--must be nice to work with.

Are you going to cast the neck hollow? IF you plan to do this consider NOT trying to carve out that pattern to make it hollow. Instead make a channel of the back of the batter board that it'll get mounted to when they gate it and port it for sand.

For instance if you just wanted to scoop out a few rough grooves/chambers in the inside of the neck, you could use a wood router and a straight-edge (but into the batter board). Pretty fool proof. If you want to try different neck wall thicknesses, this would let you experiment really close to the edge of the envelope but without any risk of damage to your baby, the primary pattern.

Oh, yeah, consider putting in some 1/8" (or what you happen to have) sized alignment pins in the neck while you still have your fiducial markings (before you sand and finish and every surface is round). If you put these on the center-line of the neck (at a fixed spacing so you can drill them by measurement into other things ... you'll find it goes a long way to helping align the cavity in the neck if you choose to go that route.

Oh yeah, those alignment pin holes have to be drilled square or they'll be of no use.

Hope it helps. You're obviously off to a good start. Phil in Seattle

[skinny honkie]

Yeah, 2% shrinkage as I understand it. I'm interested to see what that does for my scale length, because I'm not sure if that means 2% of total volume or off each dimension. Thinking about it, it would probably be volume.

I'm gonna go with a solid, one-piece neck - I prefer the simplicity. However, I am going to cast a hollow shape like a bathtub section between the bridge and the neck (as per those TB1000 flickr shots I linked a few pages ago), and I've been wondering about the best way to do that. Do you reckon putting a positive solid on the batter board is a better option over routing the pattern for this?

[ptay]

That shrinkage figure is off any dimension. Patternmakers have rulers that are 2% oversized. Pretty funny when you think about it.

Doing a bigger cavity that's thicker than the 1" mounting board is possible, but you're not going to do by carving into the mounting board alone. Until you've made a few patterns, this is a situation where working with the people at the foundry (the people who'll be gating your patter and mounting it) will help.

The parting line on the mold doesn't have to be flat, of course.

Some foundries use _a lot_ of what they call "cores" which are sub assemblies of packed sand ... for making hollow items fast and easily. This might be another option for you.

[skinny honkie]

Did some mental calculations....my 25.5" scale could end up being 25", which I think is the same as the original beans, assuming that a 2% shrinkage applies to the length of the cast piece.

I lol'ed when I figured that out. I swear I am not that much of a lamer in real life.

BTW, that wood is fantastic. I don't know what it gets called up there in america, or even if you guys have it there. It tends to get used for patio furniture here, because it's very insect and water damage resistant. I've been really impressed with its stiffness and also its resonance - I'm going to use it for the body of the guitar.
I've really like working with it. To the extent that I'm almost considering slapping a fretboard on the pattern and stringing it up. Also, I better give zom-zom a nudge and confirm his curmudgeonly suspicions that making a guitar out of wood is indeed very enjoyable.

[skinny honkie]

Gotoh bridge turned up - is nice, yay!
Wilkinson tuners turned up - they feel pretty rough, I gotta say. Somewhat underwhelmed, in fact. They feel like the cog on the bottom of the string-post has been cast, and no-one ground off the die-marks. Once every x turns, you can feel the tuning button gets tighter and sort of "lumpy-feeling".
However I was able to lay them out and ascertain that my whacky headstock layout is SPOT ON, and I'm pretty stoked about that. I guess they'll do for now.
This might sound a little wrong, but I'm gonna cast the nut as part of the neck. Sure, it'll be a bitch to alter in the future, a one-way road to larger string sizes for one thing, but I'm thinking I'll just go all-in. If I'm gonna cast a one-piece mofo, why the hell not try and make it as one-piece as possible? It seems silly to me to have an adhesive attaching a different solid between the string and the main resonant body.