Official Luthiers Forum!
http://w-ww.luthiersforum.com/forum/

Archtop Neck Construction
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=54884		 Page 1 of 1
Author:  solaris72 [ Wed Apr 06, 2022 11:22 pm ]
Post subject:  Archtop Neck Construction
Hello,

I've started the neck on my first archtop build but am getting bogged down in the details. I've listed my questions below. Any thoughts would be greatly appreciated.

1) What are your opinions on carbon fiber rods? It seems like a good idea to put them in. The bendetto book recommends a rather elaborate routing jig to make the slots but I feel like I could just do it on the table saw. The important thing seems to be that the slots are parallel to the sides once they are tapered.

2) The book gives the option of two nut widths - 1 11/16 and 1 3/4. Any opinions on the two options? How do they impact the way the guitar plays? I'm making this guitar for my use and I have large fingers so would the wider nut make it any easier to play? The book also recommends different neck thicknesses for the two widths - 5/8 and 9/16 respectively (before addition of fingerboard).

3) What is the best way to locate the nut on my unfinished neck? A lot of the directions in the book are based of nut/fret position but I'm not sure where to measure from. From what I can tell, the fret side of the nut sits is 3/8 inch down from where the head and the neck meet. I bought a 24 3/4" Gibson fret scale from Stew Mac - any advice on which of the three scales to use?

Image

4) The fingerboard I bought is only .235" thick and not the full 1/4 that the book talks about. I already added the neck taper and when I lay the fingerboard on top of it, it measures .855 in the vicinity of the 3rd fret and .900 near the heel. This seems comparable to the measurements I've found elsewhere on the forum but since I still have to shape the neck I'm sure it will come in at least a 32nd less than what it measures currently, making it quite thin.

5) How do you like to slot you fingerboards? Any recommendations on how to build the jig? Also, what depth should I slot them at? This obviously depends on what fret wire I use. What I'm not sure about is how deep to cut the slots considering that afterwards I'll radius the fretboard, making the slots less deep at the edges.

Thanks for all the help!
Author:  joshnothing [ Thu Apr 07, 2022 5:55 am ]
Post subject:  Re: Archtop Neck Construction
solaris72 wrote:
Hello,

I've started the neck on my first archtop build but am getting bogged down in the details. I've listed my questions below. Any thoughts would be greatly appreciated.

1) What are your opinions on carbon fiber rods? It seems like a good idea to put them in. The bendetto book recommends a rather elaborate routing jig to make the slots but I feel like I could just do it on the table saw. The important thing seems to be that the slots are parallel to the sides once they are tapered.

2) The book gives the option of two nut widths - 1 11/16 and 1 3/4. Any opinions on the two options? How do they impact the way the guitar plays? I'm making this guitar for my use and I have large fingers so would the wider nut make it any easier to play? The book also recommends different neck thicknesses for the two widths - 5/8 and 9/16 respectively (before addition of fingerboard).

3) What is the best way to locate the nut on my unfinished neck? A lot of the directions in the book are based of nut/fret position but I'm not sure where to measure from. From what I can tell, the fret side of the nut sits is 3/8 inch down from where the head and the neck meet. I bought a 24 3/4" Gibson fret scale from Stew Mac - any advice on which of the three scales to use?

Image

4) The fingerboard I bought is only .235" thick and not the full 1/4 that the book talks about. I already added the neck taper and when I lay the fingerboard on top of it, it measures .855 in the vicinity of the 3rd fret and .900 near the heel. This seems comparable to the measurements I've found elsewhere on the forum but since I still have to shape the neck I'm sure it will come in at least a 32nd less than what it measures currently, making it quite thin.

5) How do you like to slot you fingerboards? Any recommendations on how to build the jig? Also, what depth should I slot them at? This obviously depends on what fret wire I use. What I'm not sure about is how deep to cut the slots considering that afterwards I'll radius the fretboard, making the slots less deep at the edges.

Thanks for all the help!


Welcome! Is this your first attempt at a guitar, or have you built other types of guitars before and this is your first archtop?

1) I don’t use cf rods but many here do, they may offer some specific help. I will say that of course many fine archtops, including many, if not most, of the greatest ever produced during the golden age did not use cf rods in the neck. Well chosen wood, carefully constructed, and with a well-designed truss rod will handle the tension.

2) This is a very personal choice. If you don’t already have a favourite width, take your ruler and visit a music store. Play as many things as you can and measure the ones you find comfortable. You aren’t limited to only these widths, you can make it a little wider or narrower. Those are just conventional widths that many players are familiar with.

3) There’s no “best” way to do this, just different ways. You can locate the nut at the start of the neck surface and butt the fretboard up against it. You can angle the bottom of the nut and sit it on the slanted surface of the peghead. You can leave the fretboard longer and rout a shelf or channel at the “zero” fret location to hold the nut. There’s so many decisions to be made when building a guitar, and so many ways to skin a cat - my advice if this is your first guitar is to follow a single methodology (eg one author/book) and ignore other options for now. If you closely follow a single good methodology, all the design decisions that have been made will be compatible and you will succeed- mixing and matching can cause unforeseen issues as the build progresses.

In terms of the three Gibson scales - 24 3/4 is conventional for archtops - the stewmac rule has some different “versions” of that scale length as Gibson changed it a little over the years. I say it doesn’t greatly matter as long as you make sure to always use the same version of “24 3/4” throughout the build.

4) I wouldn’t sweat the thin fingerboard presuming it was true, straight and dressed at that thickness. If it’s that thick but rough or warped and needs dressing, it’s too thin. But this leads to my next answer …

5) Tooling up to slot super accurately can be expensive if you’re just making one or two or five guitars. Consider that many vendors will sell you a dressed, radiused, slotted, ready-to-use fretboard in the scale length of your choice, for less than $40. You’ll spend more than that just buying a good fret-slotting saw.

If you want the challenge of cutting your own slots, a mitre-box style jig is relatively simple to build - look at the Stewmac one for design ideas. Or you can build a cross-cut sled with an indexing pin and slot on a table saw. Both methods depend on a template with accurate indexing holes for your desired scale length. You need to make (accurately!) or buy that.

If you’re skilled enough with hand tools, you can measure, mark and slot by hand, with no jig.

Personally, I slot with StewMac’s miter-box jig. I have templates for common scale lengths. When I’m doing a one-off in a new scale length, I just buy a slotted board rather than retool.

Slot depth - I initially slot to a depth of around 2.5mm. Later, when fretting, I check each slot and may deepen any a little if they’ve lost too much depth during the subsequent build process, as you have recognised can happen. My advice is, rather than saw them overly deep in fear they might end up too shallow, just embrace the fact that you may need to run a saw through them again later in the process. You can keep more meat under each fret this way.
Author:  solaris72 [ Thu Apr 07, 2022 10:12 am ]
Post subject:  Re: Archtop Neck Construction
Thank you Josh!

This is my first attempt at a guitar. The questions are a give away:)

It does seem like there is a lot of personal choice and I'll just have to choose a route and commit to it. Spending some time at a guitar store with a ruler sounds like a good idea.

As for slotting and radiusing the fretboard, I'd hoped to do it myself, but, for the sake of time and my sanity, purchasing one premade might be the better option.
Author:  Freeman [ Thu Apr 07, 2022 10:32 am ]
Post subject:  Re: Archtop Neck Construction
Taylor, I just finished building a little archtop guided by Bob's book. It is my 29th guitar so I have a little experience but my first acoustic archtop. I have done carved top electric guitars. Some quick answers to your questions.

1 - I have never used carbon fiber on my necks up to this point and if the fretboard extension is glued to the top I don't think they are necessary. However the f/b extension on an archtop floats above the top of the guitar and I didn't want any humps or bumps at the joint so I put them in. They also give a little reinforcement at the scarf joined head - a weak spot on paddle head necks. I bought the CF from LMII and simply routed two slots when I routed the truss rod channel

2 - Nut width is a personal playing decision. I happen to like slightly wider nuts and 1-3/4 is my standard for any acoustic guitar. That is what I used on mine.

3 - I start building a neck by laying out the nut - I just draw a line and say "there is the nut". Using a fret position calculator (StewMac has a good one) I lay out the 12th fret and the one at the body joint (14th for an archtop). Later when the neck gets mated to the body I lay out the bridge location.

There are a couple of decisions to maker about the nut - how thick it will be, whether it sits on the flat or angled part of the head.

4 - All my fingerboards are 1/4 thick. I don't see why a slightly thinner one wouldn't work but I haven't tried. I use 1/4 tall binding which makes a flat surface for my router when doing the inlay

5 - I can slot fretboards but decided a long time ago to buy pre radiused and slotted boards from someone like LMII. You can buy slotting miter boxes and all sorts of jigs, some folks do it on a home cnc. I do lots of different scale lengths and its just so easy to order what I need.

It is a bit of a hassle to embed pictures in OLF posts, I would have to resize them. Howeveer I did do a build thread on my archtop on another forurm where I show most of the things you ask about. You might find it helpful to skim thru this

https://www.tdpri.com/threads/lets-buil ... p.1085372/

And please don't hesitate to ask questions if I can help
Author:  Ken Nagy [ Thu Apr 07, 2022 3:31 pm ]
Post subject:  Re: Archtop Neck Construction
I've only done a few guitars. I'm not making them professionally, so I'm not worried about a scale length. On my arch top, I think I made it 640mm, for the Stauffer I think it was 620. Do people get obsessed with scale length? On violins they seem to, but if they didn't know, it might not bother them.

I figured out where the frets would be with a calculator, and marked them on each side of the fretboard with pencil. Connect them with a line. Saw on the line to about the depth of the tang. It worked out fine, it isn't hard, and doesn't take much time. You can even buy, or make some sort of miter box, that has sides that automatically set the depth of the cut. I checked with a fret with the barbs removed.

I think that I've sawn them both with the board flat, and with the radius already on. I don't think it made any difference. You can be sure that the depth is good on the ends if they are already radiused though. It might be a little trickier to get it square that way. I didn't use a miter box.

The arch top has a compound radius, 12-16 inch or something. I don't remember. I figured out the radius on each end, and blended it together with a straight edge. It works fine. The Stauffer was probably supposed to be flat, but I made it 16"; the fret wire I had was pre-bent at 16". Go with the flow.

I've made violin fingerboards, but it isn't difficult with a plane, and scraper.

If you don't feel comfortable, buy one. You can buy them with pseudo binding, but if you want inlay on the edges for bling, you might have to do that yourself. I did the binding on the Stauffer. The next one should be better. To me, it is more trouble than sawing slots. Your eyeballs may be better than mine.

An arch top makes the placement of the neck less of a problem: the bridge is placed wherever you want it. Of course you WANT the 14th fret right at the body join, but like a violin or cello it is up in the air anyway. How do you get it right? The Stauffer was up in the air too, and had a pinned bridge; but with measuring I still managed to get it right on. And it has zero compensation at the saddle!

The thickness of the fretboard is not a problem, as long as it is deep enough for frets. The plans I have on guitars from the early 1800's have 3mm thick fretboards. That's what I used on the Stauffer. It was bendable!

I put a truss rod in the arch top. I haven't played with it. The others are nylon strung, and are just wood.

I had the most trouble just putting the tuners in! I didn't have the right size drill, reamer tool.

Go on and do it. The whole process is learning how to do it with less mistakes, and how to fix the mistakes so they won't be noticed.
Author:  Alan Carruth [ Thu Apr 07, 2022 3:40 pm ]
Post subject:  Re: Archtop Neck Construction
I have to wonder if the sot depth really makes any difference, other than cosmetic. So long as the frets are properly seated, so that the bead is tight against the top surface, space under the slot should not matter. Making the slots too shallow is a real problem, though.

I usually bind the fretboard on archtops. I make the slots deep enough so that there's no chance of the tang bottoming out before the bead seats. I use strips of soft plastic of the correct thickness, cut from polyethylene can tops, to fill the slots before cutting the board to width and gluing on the binding. This keeps the glue, or anything else, from getting into the slots while you work. I only remove the plastic strips when I'm ready to fret, and I've got nice clean slots to work with.
Author:  Terence Kennedy [ Thu Apr 07, 2022 6:25 pm ]
Post subject:  Re: Archtop Neck Construction
I run the carbon bars into the extension and into the headstock. I made a router jig to extend the slots into the extension. It keys into the slot in the neck. There is a stop for the router base and you just adjust the length as needed.

I have a second jig to extend the truss rod slot into the extension with a different guide that fits in the truss rod slot

ImageB80B8F9F-835B-4292-969B-581B9B937EDB by Terence Kennedy, on Flickr

ImageE4982FFF-6262-477B-9A27-606407D29F84 by Terence Kennedy, on Flickr
Author:  Darrel Friesen [ Sun Apr 10, 2022 4:36 pm ]
Post subject:  Re: Archtop Neck Construction
"3) What is the best way to locate the nut on my unfinished neck? A lot of the directions in the book are based of nut/fret position but I'm not sure where to measure from. From what I can tell, the fret side of the nut sits is 3/8 inch down from where the head and the neck meet. I bought a 24 3/4" Gibson fret scale from Stew Mac - any advice on which of the three scales to use?"

You'll have to decide whether you will be using continuous purfling that continues from the headstock to the fretboard in which case you'll want to do the fretboard stop that Benedetto details in his book. If not, then make sure the joint where the headstock meets the fretboard is perfectly square and which will be where the nut meets the end of the fretboard regardless of whether you have chosen to have the nut on the headstock with an angle on the bottom or if you want the nut on the fretboard side of the neck. If you have already cut the dovetail then you have established your 14th fret location where the neck joins the body. This will now dictate where the nut goes regardless.

I always leave the heel of the neck oversized slightly until I get the headstock squared to the flat part of the neck where the fretboard will go as close to perfect as I can. It may just be the picture but the headstock to neck where the nut will sit looks a hair out to me. I'll then cut the dovetail or tenon making sure that the length is correct from the nut to the 14th fret where the neck joins the body. I usually make laminated necks so it takes a little more work the way I do it to ensure the headstock to neck transition is square.

Sorry for the confusing explanation. My first guitar was also an archtop. Good luck on yours.
Author:  TimAllen [ Mon Apr 11, 2022 12:35 am ]
Post subject:  Re: Archtop Neck Construction
Good answers to all the questions! Re cutting a truss rod slot, I've made about 10 necks and cut all the slots with the table saw. I glue in a little fillet at the nut end so the slot is stopped. I'm comfortable using the table saw for lots of things, and only make 1-2 guitars a year. I'm sure routing works well, and would be more efficient once you were jigged up and used to the procedure.

As has been said, nut width is a matter of personal preference. However, for steel strings, 1 11/16" is by far the most popular width, so I don't think you'd go wrong choosing that.
Author:  Freeman [ Mon Apr 11, 2022 12:25 pm ]
Post subject:  Re: Archtop Neck Construction
solaris72 wrote:
Hello,


1) What are your opinions on carbon fiber rods? It seems like a good idea to put them in. The bendetto book recommends a rather elaborate routing jig to make the slots but I feel like I could just do it on the table saw. The important thing seems to be that the slots are parallel to the sides once they are tapered.



I don't know if Solaris is still watching this but I will add one more comment. I am used to building my necks dead flat and letting string tension pull a few thousands of relief, which I control with slight truss rod tension (I use double acting rods and like 4 or 5 thousands of relief). The neck on my recent archtop build has two carbon fiber beams and under string tension (12's) I can just barely measure the relief - maybe a thousand or two. It plays fine but I wonder if its possible to build the neck too stiff.
Author:  Alan Carruth [ Mon Apr 11, 2022 4:20 pm ]
Post subject:  Re: Archtop Neck Construction
I generally think of the purpose of the truss rod as balancing off the bending load on the neck, so that it doesn't cold creep over time. A piece of wood subjected to a long-term bending force, even if it's well below the nominal yield stress, will creep over time, taking a set in the direction of the load. You can see this in telephone poles that have a wire off them to a house but have not been guyed up; they bend toward the house. You could not get them to bend that much with a short term pull of any reasonable magnitude, let alone the small force the wire puts on, but over time... If you rely on the string load for relief you're working with an unbalanced load, and over time it's likely to pull the neck up further.

I used to run into this when I did repairs for a local music store. They'd get in low-end electrics with straight necks and no tension on either the string or the rod when they opened the box. They'd tighten up the strings and hang them on the wall. A year or so later, after they'd been sold, they'd come back with unplayable high action; 1/4# at the12th fret or more sometimes. The only thing I found that would correct this was to remove the stings and crank up the tension on the rod for a a few days or a week, until the neck was pulled back straight with no load, either from strings or rod. Then you could level the frets, get the relief right, and put on the strings. You see how much the neck pulls up under string load, and put enough tension on the rod to get it back to where it was. Often the wood on these was not wonderful, and the neck would take on the look of a snake with indigestion. And, of course, they needed the instrument before next weeks' lesson, and it had to be perfect. I don't do repairs any more.... ;)
Author:  solaris72 [ Tue Apr 12, 2022 2:38 pm ]
Post subject:  Re: Archtop Neck Construction
Thanks to everyone for all the great insight. I still have lots of questions but I do feel more equipped to get past my doubts and start making cuts.

I see now that the nut position is already determined based on the fact that the 14th fret needs to be where the neck meets the body. I could change it slightly by choosing a different scale length but I will just go with the Gibson 24 3/4.

As far as carbon rods go, I will go ahead and insert 2, one on either side of the truss rod. I realized that I cut out my neck incorrectly. The board I used was quarter sawn to start so now that its been turned and glued the neck has a flat sawn pattern. What should I use to glue the carbon rod in place? Titebond or epoxy?

For the truss rod, what do people use to wrap it? In the book it says that an unwrapped rod can cause feedback later. Is electrical tape a good choice? The truss rod I bought is too long (because I didn't extend the slot into the neck extension) so I will have to cut it and then recut the threads. I also bought a double action rod but it's too tall to fit comfortably in the neck I've made. There would only be maybe 1/16th material remaining if I cut the slot deep enough to accept the double action rod. Have other people used double action rods in archtops? I would like to switch to this as it seems to be the better piece of technology.

For the fingerboard, I think I will just go for it and cut it by hand. I mean, it's my first guitar so why not. I need more practice with hand tools anyways.

I will bind the headstock and fingerboard. If I go with a 1 3/4" nut width, should I then add the thickness of the binding to the nut width to figure out the taper? The book mentions that the binding is part of the playing surface. I don't really know how to factor that in as I don't own a guitar with a bound finger board.
Author:  Freeman [ Tue Apr 12, 2022 2:52 pm ]
Post subject:  Re: Archtop Neck Construction
More comments

- one of the very first decisions I make when I decide to build a guitar is the scale length - that determines a whole lot of things. Gibson scale is quite fine for an archtop, after all that is what Gibson used. The 14th fret is the traditional neck to body joint. That also determines bridge location.

- carbon rods certainly won't hurt anything, just make sure your neck is dead flat when you install them. Use slow set epoxy for the adhesive (I think Benedetto uses CA). I use double acting truss rods from LMII for everything I build - there are no problems with depth in my necks.

- make youself some sort of little miter box to support your saw when cutting your fret slots. Check the depth of the slot with a piece of fret wire that you have filed the barbs off of. Its tedious but very doable.

- if you bind the fretboard that becomes part of the width of the playing surface. You might want to actually lay out your fretboard profile - there are several measurements (width at the nut and the body joint or 12th fret, string spacing at the bridge, string offset from the sides of the board). In reality two of those are independent (and you can decide which ones), the others follow.

If you have Benedetto's wonderful plans you can pick all of this from the plans. I also gave you a link to my recent archtop build, did you look at it?
Author:  solaris72 [ Tue Apr 12, 2022 7:55 pm ]
Post subject:  Re: Archtop Neck Construction
Freeman,

I have been perusing your build thread. Tons of good information. Thank you! I have maybe 15 pages left to scroll through.

I hope to get around to slotting the fingerboard soon. In the near term, I think I should get the truss rod set and glued in along with the carbon fiber rods.

In other news, I finally cut the body mortise. It took me about 3.5 months to build the jig and complete a successful test cut. So that's about the pace I'm moving at!

Image
Author:  Dave m2 [ Thu Apr 14, 2022 11:04 am ]
Post subject:  Re: Archtop Neck Construction
Slotting the fretboard by hand is not hard.

Get a good light on it.
Clamp your (good quality) ruler to the board so it doesn't move.
Arrange a magnifying glass.
Mark your positions with a sharp knife with a flat side.
Do a sanity check that the positions are right, perhaps compare with another neck.
Then score across the board using a square two or three times.
Use a tight fitting mitre box as has been said which can be used to set the slot depth.
Oh and do all this before tapering the board so you can use a square.
After radiussing the board you will need to deepen the slots at the edges. Use a depth gauge on your saw.

Cheers Dave
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/