Neck set / depth

[buddyellis]

I'm at the point where I'm about to glue the necks on my next two, and was wondering how you all generally get the depth of the set right. For me, it's mostly been a ####-shoot and I'm wanting to examine this part of the building process a bit more. When you set the neck in, how to you determine how deep to set it in the dovetail? How do you measure the height from the middle of the soundboard dome?

[sunburst]

I make a gauge that is a straight edge that lies on the fingerboard surface of the neck and extends over the top. I attach a short ruler so that it projects down from the straight edge toward the bridge position of the top. I set the gauge so that it projects the amount that will give me the bridge height I want, and fit the dovetail until it touches the top.

[s1m0n]

I make a gauge that is a straight edge that lies on the fingerboard surface of the neck and extends over the top. I attach a short ruler so that it projects down from the straight edge toward the bridge position of the top. I set the gauge so that it projects the amount that will give me the bridge height I want, and fit the dovetail until it touches the top.

That sounds simple enough. Does this mean that there's no need to build in an allowance for the neck to flex slightly under tension?

[Hans]

Buddy, here's the jig I made many years ago from a mangled F/B :grin:, a wedge of maple representing the frets plus the string action and an ebony straightedge with a screw at the bridge location.

http://i723.photobucket.com/albums/ww234/ivoroid/m3-1.jpg

I make sure my neck sits around 1/4" above the top (riser block is around 7/16" from the rib).

[sunburst]

...Does this mean that there's no need to build in an allowance for the neck to flex slightly under tension?

I would have to say that an allowance is built in because I arrived at my measurement by "reverse engineering". In other words, I made mandolins, measured the distance with the gauge, then saw what bridge height I got, then adjusted the gauge height until I got the bridge height I wanted. In other other words, it was "trial and error", though I was lucky enough to avoid neck sets that I would consider "errors".

My jig works the same as Hans', but I measure without the fingerboard in place.

[Lefty Luthier]

That maple wedge is a great idea. I have always used a 1 x 1 steel angle atop the fretboard (pinned in place) with a screw threaded through at 13 7/8 to gauge the distance but Han's tool is far more elegant.

[buddyellis]

Han's tool is pretty much how I've been doing it before, although mine is just a stick of maple with a spruce pin at 13 7/8. I guess the height is just 'trial and error' and I need to measure some mandolins to see what works. Here's the neck, btw:
http://lh4.ggpht.com/_0Sp-JKdheeQ/S4KpsiiHPzI/AAAAAAAAHV4/Wd2ybtze2D4/s720/DSC_4822.JPG

I'm assuming you guys pretty much have everything done on both pieces before the neck goes on the body (i.e. before finishing, the neck set is pretty much the last thing that goes together)?

[Mark Franzke]

I use a gauge similar to Hans' above, that lays on the flat part of the neck and has a wooden pin at the other end. When the pin touches the top, the neck is at the right height. I glue the neck on before I glue the back on. I've done it both ways and there are pros and cons for each, but I do it this way now.

[sunburst]

My necks go on before my backs, but I carve and sand the necks nearly to completion before installing them, especially the heel. If the scroll and heel are completely sanded before the neck goes on (on Fs) the sanding can be done without having to work in that tiny little space between the neck and the scroll.

[buddyellis]

Last one I built ended up with string height off fingerboard is as follows (fairly low setup):

fret 1: 3/64
Fret 12: 3/32
Fret 20: 5/32

String height at bridge with current setup 15/16

Bridge height by projecting off fingerboard + frets = 25/32.

Subtract fingerboard + frets thickness (1/4" or 8/32) yields 17/32. This is the projected height at bridge of the neck sans fingerboard

I get the same measurement (17/32) if I attempt to use a ruler to project out the aproximate bottom of the fingerboard to the bridge, So I'm pretty comfortable that this is the projected height of the neck w/o fingerboard at bridge.

Now I think the height at the bridge is about 5/32 too high, so does it make sense to settle on a projected height of the neck at the bridge location of 3/8? Or maybe I should make it 1/2 so I can work down the fingerboard thickness?

[Hans]

Sounds like your neck angle is too high. Should be around 5 degrees, and the bridge should be around 3/4".

[buddyellis]

Ah, I think I'm using 6. I was just assuming I had the neck set to high

[sunburst]

I use a .020" fingerboard, a 1/4" overstand (height of neck over top at joint), about .040" height frets, and I like about 3/4" bridge height, more or less. My gauge height at the bridge location is about 1/2". I don't bother with measurements as small as 32nds, when setting the neck, I use adjustable bridges, after all.
I don't know my neck angle, and it varies with the height of the arch of the top, which I vary somewhat depending on the wood I'm using and the sound I want.

[Rob Grant]

Like John, my neck angle will depend on the arch of the top (which does vary with my instruments). Basically I use a pretty rough guage consisting of one long (400mm) and one short steel ruler (150mm). A temp. fretboard and a bit of judicious eyeball work gives me the 19mm height at the bridge that I aim for. Pretty much like Hans only a lot less "flash" (elegant).

It is possible to correct a "bad" angle by laminating a wedge under the fretboard. I did this once with a flattop and it worked a treat. The different colour timber of the wedge actually added a bit of "eye appeal" to the instrument.

Nice work on the three-piece.

[Lefty Luthier]

I generally make a neck fit check before gluing the top to the rim. I shoot for 0.42 neck over headblock at joint, which should result in 1.060 rim to string intersection point for 13.875 scale. My nominal arch height at the bridge is 0.50 above the rim, which results in a bridge height of 0.80 or a bit less depending on neck angle that I generally set at 5+ degrees. I find it easier to get the neck heel properly trimmed before gluing on top or bottom using this method. Seems to minimize guesswork.

[buddyellis]

The neck was still somewhat rough, so I just put it on the belt sander and built in a bit of a reverse angle into the top of the neck/fingerboard junction (i.e. sanded more towards the dovetail end, and took of next to no material on the nut end). I'll have to adjust my jig that I use to cut the dovetails out with (or just toss a bit of a wedge in there when I cut 'em) Thanks for all the replies folks, as always you guys are a great wealth of information. This is my #2 'scratch' and I wanted to try and work out some of the issues I had on number one (and this was the biggest one, the neck in general) I do ok with finishing, carving the plates is pretty automatic, and staining is pretty fun (even the spruce) but this dang dovetail vexes me :-)

[barry k]

......now , im even confused:confused: :confused: I use the same set up , basically as Hans and some of you others here....seems to work really well... 4-5 degree neck angle, string height for the "G" course ends up being .070 to .075 above the fret at the 17th fret with the bridge wheels set all the way down. Gives you plenty of room to move up the bridge for that "manly" action.

[Dale Ludewig]

I still basically use something like Roger Siminoff does. Like John, I put my neck in almost completely sanded, especially at the heel. I sink the whole neck into the headblock and do it before the back goes on. I use a cradle like thing that holds the body at a certain height right where the bridge is going to go. It is symetrical side to side and only touches the top in the middle of the bridge area. It is made to compensate for the fingerboard height, frets, action, etc. This all done upside down and with the back off it's easy to level the heel to the back rim before the back goes on. I also dowel the neck in before the back goes on. A dovetail is probably more elegant but I've never had a neck joint move.

The whole gluing job is done on a board that is set up to let me clamp on both sides of the headblock and on the heel. A center line is drawn down the setup board and also on the neck and body. By putting my pressure only at the headblock and fiddling a bit, I can get virtually perfect alignment on the center line but can also by measuring the distance from the top (upside down now) to the board and make sure that there is no twist going on.