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uncle.fogey - Posted - 05/11/2012: 14:04:55
Now I’m going to make a neck - in fact 2 necks. One will be cherry and one will be maple.
I’m going to be illustrating, to the best of my ability, how to make all the parts of the neck, at least the way I do it.
I’m going to try to make the two necks different in some ways if I can to show different things.
Of course, I welcome any ideas anyone might have.
Here are the aspects I will be trying to explain:
It’s hard to separate the fingerboard from the neck, and the very first thing I have to do is to figure out what length the FINGERBOARD is going to be, because that determines how long the neck is.
There was another thread a few days ago about scale length, and I posted some diagrams about that. I have a few other ones I’ll use here in order to explain how you determine the length of the fingerboard, and thereby, the length of the neck.
On that thread, someone requested that it be explained from the bridge out, so that’s what I’ll do.
I can re-post stuff from that thread onto this one, if it helps.
FIRST AND FOREMOST - I’m showing how I do it, and explaining MY design process. in a one-off custom banjo, you can decide all these things for yourself - even if someone else is making it for you, it’s good to know how it’s done.
STEP 1 - Determine where the bridge will be placed on the head:
I am making banjos with 11” heads, and I want the bridge position to be 7 inches from the fingerboard edge of the head.
that’s 7/11, or .64 of the way across, just a little bit less than 2/3, which would be .66. I like this position because of the way it sounds, but you can choose any position you like. Generally, the closer you move the bridge towards the middle of the head, the more soft and “plunky” it’s going to sound, and the closer you move it towards the tai\lpiece, the more bright and snappy - maybe “harsh”. A lot of players describe the “center of the head” sound as “tubby”, and When Vega introduced the “Tu-Ba-Phone” design back in the day, they spelled it “Tu-Ba-Phone” because they didn’t want it to be mis-pronounced “TUB-a-Phone”.
Lots of players LOVE that tubby sound - it’s a “period instrument” kind of thing, so if you like that, design for a more center-of the head bridge placement, build it. If you don’t, stick with the 7/11. Go farther south at your own risk, but I once (40 years ago) made a 26 3/8“ scale neck for a 10” pot, and it was only “OK“. When you venture out of the comfort zone, it gets uncomfortable and "OK"
SO, I start out with a drawing of an 11” pot, showing the bridge at the 7/11 position.
STEP 2 - Determine the scale length you want:
I decided I wanted a scale that was a LITTLE less than 27”, but longer than my old Gibson 26 3/8“, so I decided on 26.9” I like this scale length, having gone through shorter scales in my youth, thinking they would be easier to fret, or something like that. I have now made a lot of banjos with this scale, and it has never let me down.
The shorter the scale, the looser the strings will be and the more likely they will buzz, so you need a higher action or heavier strings to compensate for the looser string tension, etc etc.
We all have our individual preferences, and I like 26.9”.
SO, on my drawing, I project 26.9 inches out from the bridge position, and that gives me the “nut position”. What falls between will be the fingerboard, and the fret spacings and the number of frets is a mathematical thing.
STEP 3- calculate the fret positions:
NOW, without entering into a discussion of historic tempering systems and the like (and I realize that Gibson, during the Lloyd Loar era, experimented with an unique fret spacing system for a while), I’m going to use the modern day accepted formula. (PLEASE - if you want to create an untempered banjo with some goofy fret placement system, don't respond to this thread - PLEASE PLEASE). Start your own, PLEASE.
Here’s an interesting treatise on it: liutaiomottola.com/formulae/fret.htm
I’ll quote from it:
“Unless you are building or repairing historical instruments, use the equal temperament constant of 17.817. It is the currently accepted standard.”
SO,
Here’s a spreadsheet showing the fret intervals for a 26.9” scale. You use the running total column.
Using that system, you can calculate all the fret positions, which I show here:
STEP 4 - make a fingerboard diagram:
If I impose an outline of my fingerboard on this drawing, I can make an accurate drawing of the fingerboard:
Stone walls tomorrow morning
Tall Grass - Posted - 05/15/2012: 09:03:40
Friend Levan: Hope I'm not intruding on this august forum, I couldn't resist. Tis a joy to be simple Tis a joy to be free - - - -Waiting but VERY patient. Continue when you can, and put me down on your book list. Adios!
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uncle.fogey - Posted - 05/15/2012: 13:01:54
We got a lot of rain in PA - no mortar mixing, so I can work on this thread. I have a LOT of info, but I have to organize it.
The next step is to pick good pieces of wood to make my necks out of.
I’m going to make one neck out of cherry and the other out of curly maple - one very stable wood (cherry), and the otherone not very stable. By using laminations and reinforcement techniques, and paying attention to the grain direction, I will be able to make necks that don’t bend or twist and are adjustable .
In the spirit of providing good engineering information, or to quote Dorothy L. Sayers, “to create the illusion of efficiency”, I was going to post a lot of “physical properties of wood” charts, which I got from the Dept’ of Forestry and various flooring manufacturer’s websites.
I started looking at these “modulus of elasticity” MOE (as opposed to Larry and Curly) (stiffness) numbers, and I said “HUH”? Wood from different trees, grown in different places is different. It’s not like metal which has exactly the same characteristics from piece to piece.
Not long ago, I conducted a simple experiment with pieces of wood I actually use - I wanted to see how stiff they were one to the other:
I made strips of wood 1/4“ thick, 1” wide, and 24“ long, propped them between 2 bricks, weighted them down in the middle with 2 bricks, and measured how much they bent or deflected.
Here they are from the stiffest to the least stiff.
2 pieces of cherry I tested were very different, and the Brazilian rosewood, which should have been the stiffest one wasn’t. The poplar was stiffer than I thought it would be, but.
What I learned from this was that I ought to depend on good construction and reinforcement rather than using no reinforcement and trusting charts showing what the stiffness of the wood “ought to be”.
Nonetheless, the quality of stiffness AKA the modulus of elasticity , is the most important (engineering) quality for a banjo neck.
This quality is most important for one piece necks. For laminated necks, we can often overcome inadequecies in MOE by good design, and construction.
“HARDNESS” is important for fingerboards, as well as “darkness”. Darkness you can see with your eyes, and I think the Janka scale of hardness is probably more universably reliable than the modulus of elasticity data I found.
Nowadays with 2-way truss rods and carbon fiber rods, we can make a viable banjo neck out of species of wood that wouldn’t have been feasible 20 years ago. Nonetheless, I am sticking with the time-tested varieties, both of them, maple and cherry, which are closed grain. This will make finishing easier by eliminating the step of filling the grain - PLUS, I want the necks to match my rims.
In order to make a one-piece neck, you need a piece of wood that’s 2” x 3” x 28” for a one-piece neck, and a piece that’s 1” x 6” x 28” IMPORTANT - I’m talking about ACTUAL SIZE, not nominal size - a nominal “1x6” is really only 3/4” x 5 1/2”.
For this project, I am making laminated necks. I would make a one-piece neck for some historical restoration, or a conversion neck for a banjo where the original neck was one-piece. I HAVE made them - I just don't like to. Here’s a restoration of a one-piece Gibson neck:
All my wood is air dried outside, under a roof. The cherry has been seasoned for about about 8 years , the maple at least 30 years. As a general rule, 1 year for each inch of thickness AFTER it’s been cut and stickered.
I always being it indoors for at least a month to acclimate and do any “happy to be inside” dancing it’s going to do before I cut it and plane it - you never know what it’s really going to look like until you plane it. BY FAR the biggest problem in my shop is the storage of acclimated wood, and wood in process - I can't put it outside, and it takes up space inside and collects dust. I wish I had a separate heated space to keep it, but I don't.
Nowadays, VERY few logs are actually “quarter cut” It’s wasteful, and requires a special carriage for the sawmill. The way they normally saw logs, most of it is flat cut, and there are quarter cut boards in the middle, and one side of flat cut boards is often “quarter cut”. If you sort through the stacks, you can find good pieces.
For a one-piece neck, I would want a quarter cut piece with the grain running top-to bottom of the blank. to make a laminated neck, the kind of board in the picture below is good - we are going to cut two opposing neck halves out of it, making it for all intents and purposes, quarter cut, so we want the end grain to be symmetrical:
Here’s how it will be cut up:
The “waste” piece in the middle will be used to make perfectly matching peghead “ears”, and the dowel stick - maybe a few bridges.
Next - which way to you orient the grain?
uncle.fogey - Posted - 05/16/2012: 11:53:39
Michael, I cut the boards like that because it is less wasteful of the veneer I use for the laminations in the middle, plus, as you will see as I continue this, it makes it easier to see what you are doing as you glue everything together.
You COULD cut the board like this:
You would get a more perfect book-match, but in the case of curly maple, you could lose some excitement in the grain, depending on the board.
I will explain this in more detail soon.
By the way, your thread about the neck extension is very interesting.
Ken
uncle.fogey - Posted - 05/17/2012: 10:27:52
quote:
Originally posted by rudy
quote:
Originally posted by banjonutter
I've read elsewhere that some people rotate the centerline of the neck counterclockwise such that the endpoint of the centerline at the nut is 3/16" from its original position at dead center. Then the frets are drawn/cut perpendicular to this rotated centerline. I didn't see where you do anything like that, do you keep everything centered? Do you know why they do such a thing? How would you describe the centerline of the neck in relation to the pot?
Not to distract from Ken's essay, but this relates to when the neck is actually being mounted to the rim. You most like ly ran across the statement on my website. If you go to the link below and scroll down to "Banjo Neck Geometry" you'll see the complete explanation.
bluestemstrings.com/pageBanjoC...ips1.html
The way I align the neck is by using a line that runs from the third string nut slot to the center of the tailpiece as the centerline. The frets are perpendicular to that line.
After I cut the heel, and before I set the dowel stick, I firmly attach the neck to the fully assembled pot via a cleat and screw through the dowel hole in the pot as a "DRY FIT". This also verifies the center point of the dowel mortise, yet to be drilled.
I then attach a mason's line to the peghead, and run it through the 3rd string slot on the nut to the tailpiece lug. It has to run exactly down the center of the fingerboard from the 5th fret to the pot. If you put a bridge on the pot, you can also check what the action will be.
If it is catty-wampus in any way, you have to adjust the heel cut until it is right. THEN, drill the mortise and fit the dowel stick.
Once the dowel is glued in, this becomes 10 times harder to do.
If the neck isn't centered, the bridge will pull to one side or the other, ESPECIALLY with a non-frosted head
uncle.fogey - Posted - 05/17/2012: 17:59:11
I said I would be a little slower with the posts. I am building stone walls in the morning now that it has warmed up, plus, I have actual banjo work to do. Climbing up and down onto a scaffold carrying stones and buckets of mortar makes me tired.
Anyway, on with the neck building.
I talked about quarter sawn and flat sawn, and I'm going to assume that the kind of board you can readily get will be flat sawn and might have an end grain like this - this is a good piece - 6 inches wide:
You see that the end grain runs in a kind of arc. You want to make your 2 halves “oppose each other” - in other words the grain in one half should be exactly (as exactly as possible) opposite from the grain in the other half - a mirror image, called a "bookmatch" if something is going to move, the other side will move, too, and the two movements should (in theory) offset one another.
Since the end grain goes in an arc, there are 2 ways to cut the board into neck halves, down the middle, making a fairly perfect bookmatch, or the opposite way I showed earlier, with the "waste piece" in the middle.:
I am going to cut it so that the waste piece is in the middle, as shown on the bottom picture above. Why? I want to have an angular end grain oriented in a kind of “herringbone” pattern, and I want it to be going out from the center, as opposed to going in:
Why this way, as opposed to the other way? The other way seems better, intuitively.
It has to do with getting the “quarter figure” to show on the neck as opposed to the “flat figure”
In order to illustrate this, I turned a curly maple cylinder on the lathe, stained it a little, and sealed it roughly to bring out the grain a little - you can see what happens when you rotate it - the grain intensifies and diminishes depending on what side of the cylinder you are looking at - you want to have the quarter figure showing on the neck as much as possible instead of the flat grain:
It can make the difference between having a curly maple neck look “OK” or really strong.
uncle.fogey - Posted - 05/18/2012: 16:12:09
By the way,
as I write this - May 18th 2012. Douglas Dillard has died - May his soul rest in peace. He was my favorite banjo player bar none - I have internalized all the Dillards records, have them all including the one with Byron Berline, where I understood "A", and I have watched every Andy Griffiths episode featuring “the Darlings” at least 10 times.
When these banjos I am making for this project are finally done, the sound files I use to represent them will be either “Doug’s Tune”, Banjo in the Hollow” or both. I will miss him - his sound was always my “model” of what a bluegrass banjo should sound like, and I have always built and set up my banjos accordingly. I have a banjo like (one of) his, which I use as a test to "keep me honest" as I build banjos.
In the case of this thread,
It’s very interesting!
I was SURE that lots of people would be interested in the explanation of the grain rotation and orientation of figured maple, which took me a long time to figure out, AND a long time to figure out how to communicate it, but I’ve gotten no response -go figure. ha ha. figure figure figure.
OK - I’m making 2 banjos - a cherry one and a maple one. I want to have wood, metal parts, purfling, binding, and inlays that all work together to make something interesting looking.
I have a lot of materials to work with- cherry, maple, Texas ebony, darkened brass, dyed veneers, veneers that I cut myself, Corian, nitrocellulose, MOP - it ‘s overwhelming.
I’m a product designer, and these are products, so I have to lay out my materials and colors, just as if this was a set of mixing bowls, kitchen utensils, or chairs.
I know I’m going to be laminating center strips for the necks, cross-banding below the fingerboard and peghead. Before I start making strips of maple and mahogany where the saw kerf will be 3X the thickness of the finished strip, and cutting into expensive “made in France” dyed sycamore veneer, I have to have a plan - “a man, a plan, a canal - Panama”
SO, I work this out on my computer - Adobe Illustrator does wondrous things - I can create color stripes and other ideas using my colors.
I can “paste it in” to a photo of a neck that has the finish I’m going to use to see what it will look like:
After I have concocted a “plan”, I have to get back to reality, which, sadly, means squaring up the tablesaw blade - this is a Freud thin kerf ripping blade. It has to be 90 degrees, dead nuts, to cut these sliver thin strips:
Then I cut very thin strips from maple, walnut, and Honduras mahogany. I like these to be the same thickness as my .9mm French veneers, although even those are not consistent:
The thin French veneers tend to curl when they are wet with glue, so you have to act fast:
I do it in two stages, the first is the outer veneers, which I glue onto the neck halves and put a piece of polyethylene in between.
I make the peghead part of the veneer go at a different angle, which you can see in the pictures. I clamp the bejeezus out of these at every stage - I want to see Titebond weeping out of every joint.
Then, after these outer laminations are set, I do the inner cross-banding, based on my computer drawings.
They look like poisonous snakes at this point. When the whole thing is glued up, it looks more subdued - remember, what shows is end-grain:
Then you clamp it - a lot of glue:
As for the glue, I use a little kosher salt, sometimes, to keep it from slipping, but mostly, I'm just VERY careful - if something slides out of line, I loosen the clamps, and push it back. Titebond grabs pretty quickly.
Finally, you sand it down, and get to see the finished look.
As I said before, it isn't quite as jarring looking as the glue-up when you see it in the final view - that crazy baby puke chartreuse actually looks good!!. The dowel stick is done at the same time and in the same pattern as the neck blank:
I’m jumping ahead a little here, because some of this is the fingerboard.
Dave1climber - Posted - 05/18/2012: 19:33:14
Ken
You have come to what I think is the most interesting part of banjo building, and the part that allows the most artistic scope. Some might rightly think that it requires the widest range of technical skills also.
I found your explanation of grain orientation to be clear and concise, once again good writing and great illustrations.
Thanks
Dave 
uncle.fogey - Posted - 05/22/2012: 14:39:12
Now that the neck blanks are glued together, and the tops are sanded as well as I can get them with a disc sander, I want to get them perfectly flat.
I do this by rubbing them against an adhesive backed sandpaper strip that is attached to a perfectly flat surface - I have a piece of lab top, but a table saw table will work for this.
I scribble pencil lines all over the top of the blank, then sand it until they are gone. By this method, I can see the low spots.
Eventually you sand off all the pencil scribbles:i779.photobucket.com/albums/yy...uence.jpg" style="width: 500px; height: 925px;" />I use this flat surface for fingerboards, pegheads, bridges, sharpening chisels and plane irons - lots of things. It’s a handy tool. You could get a scrap piece of granite or marble from a kitchen counter contractor, and that would work great.
The top of the neck becomes perfectly flat, which is essential:
After the top is perfectly flat, the next step is to cut the groove for the truss rod.
With the excellent choice of products and materials available today, there’s no reason to risk having all the time and work you put into a neck go for naught because it bends.
Of course, if you are making a neck for yourself and you don’t want to reinforce it, that’s your perogative, and you are willing to take the responsibilty for it - it’s a gamble.
If you are making a neck or banjo to sell, I think it’s unprofessional and scary not to reinforce it unless it’s a historic restoration and the customer doesn’t want it to be reinforced. Ebony strips, by the way, don’t do much, but they look nice.
I use 4 different reinforcement systems:
(1) The most familiar one is the double-rod up-down truss rod kind. Several companies make these.
Here’s the way they work:
The weak spot in these is the weld, so I like to overtorque them in both directions to make sure the weld is sound:
If it’s going to break, let it break now, not after you’ve delivered the banjo to your customer and they say - “my strings are buzzing”
The Version of this called the “Hot Rod” has no weld to break, but requires a little deeper slot. They work the same way.
My favorite kind for regular length necks is the “Martin” type truss rod, which is encased in a stainless steel “U” channel, which all by itself is a reasonably decent reinforcement. I use one made by Gotoh. These are strong enough to resist twisting, and I would use these on a one-piece neck because of the extra structure.
Here’s how they work:
(3) The double rod kind, which is available in an electric bass length will work well in a long neck, BUT, longnecks can twist, which is a real problem, so I like to flank them with 1/8” x 3/8” carbon fiber strips:
With this system, you are getting “out there width-wise, and you have to be careful that you can still drill a hole for the 5th string peg.
ALSO, I think the carbon fiber strips would be overkill with the U-channel kind of truss rod
(4) You can use carbon fiber rods alone if you REALLY don’t want a truss rod - say you’re making a historic reproduction neck with a dowel stick where a truss rod wouldn’t be accessible. This will work very well, and is stiff, but is not adjustable.
Once again, I would not do this unless it was a historic reproduction, and I would explain to the customer, that this cannot be adjusted, and I cannot fix it if it goes south, east or west. I would get them to sign off on that. You’d be amazed how many out there don’t think they need an adjustable neck. Meanwhile, a truss rod costs $11 - $15 - go figure.
Cutting the slot is done with a tablesaw or router - I prefer a tablesaw because I can more perfectly tweak the slot(s)
I glue a piece of mahogany as a filler at the heel end.
The truss rod has to fit snugly, but not so tightly that expansion and contraction will cause the neck to split. Some people put a bead of silicone caulk in the slot to preclude buzzing. I do that with the double-rod type.
I like to mark the fingerboard position with pencil, allowing 1/4” for the nut.
I also cut the heel at a 3 degree angle, but a little oversized to allow for some cutting
IT IS VERY IMPORTANT to keep the neck square for as long in the process as you can - it makes everything easier to deal with. Don’t shape the neck until the very end.
Now I am going to put these aside because the fingerboards have to be done next.
I think I’m going to start a different thread for the fingerboards and switch back-and-forth.
uncle.fogey - Posted - 05/23/2012: 17:50:42
I meant to add this to the neck blank lamination sequence, but I forgot.
You can make a neck blank with the groove for the truss rod already there by making the center lamination strip the same thickness as the truss rod, and placing it down to the depth of the truss rod when you glue it up. No need, then, to cut a dado.
I used to do this all the time in the days when we used single action tension rods, and I would cut the center lamination at the proper arc:
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