Positioning scarf joint

[Mac McElwain]

I like to use an under-the-fingerboard scarf joint when building, but I'm having trouble positioning it right. I always get the tip of the join under the neck right at the point where the headstock angle breaks away and I really struggle to feather the join invisibly. How can I position the join further back down the neck so it's away from the break and therefore easier to feather?

Currently, I split the neck plank and reverse the grains. Then I taper the blank and accept that the headstock will have a slight taper. Then I cut the scarf to 15 degrees. and glue it Then I fight the feathering!!! Is there a smarter way?

MAC

[Andrew]

I’m having a hard time picturing your current process as you describe it here, but I dont understand what you mean about splitting the neck plank and reversing the grain, and I dont understand why any tapering would occur before the scarf is cut. Could you clarify or provide pictures? I don’t build much and when I do I don’t use scarf joints as of yet but it seems to me your scarf should be located and cut while the neck blank is still straight and square. I believe the location of the scarf relative to the angle break at the nut would be dependent on the angle of the scarf and the thickness of the stock.

[Mark McLean]

Is there a smarter way?  Well, there are 2 ways to do a scarf joint.  Each has pros and cons.  And there are other ways to create a headstock angle without a scarf joint.  It’s your choice.  There is a good discussion of the issues here:

https://www.gluedtomusic.com/blog/1/headstock-and-scarf-joints-expl...

I stole one of their pictures to show the two options for the scarf.  

I prefer method 2 so that the joint is not visible in the neck.  I put a face veneer on the headstock and a backstrap which extends a bit down the back of the neck.  This means you don’t see much of the joint, except on the side profile of the headstock.  As Andrew mentioned, you would normally do the scarf joint while the neck blank is still a square plank, before any tapering or shaping.  

Here is the backstrap that I am talking about. 

Alternatives to the scarf joint are discussed in the link above.  Cut it all from one piece - more attractive but wasteful of good wood and creates a headstock which is at an angle to the grain; so weaker.  Stack blocks like you do for a heel - efficient for wood, and strong, but uglier.  Or do it like a Stratocaster neck, without an angle.  It is your adventure.  

[Andrew]

Personally, I like seeing the scarf joint in the neck, and seeing a nicely positioned scarf under the backstrap would be extra sexy ;). Nice work. Comprehensive & concise response as well.

May I ask what kind of saw you prefer to cut the scarf? A mitre saw seems pretty convenient.. but maybe a table saw/sled arrangement would do nicer work of it?

[Mac McElwain]

Table saw with sled every time for me. Gives terrific control over a nerve-wracking moment!

[Mac McElwain]

Mark and Andrew - thank you both for your erudite inputs. There's a common thread here to do with cutting the scarf when the neck plank is true and square, before any tapering. Which is what I have not been doing, so next time I will change the order in which I do things. I can see how doing this would have the ability to move the join a bit.  I'm trying to achieve results like the attached. Cheers. PS - love the look of your work.

[Mark McLean]

Hi Mac

Your examples are definitely Method 1, which sounds like your previous method.  All good - but I think you will definitely get improved results with a true and square plank.  I follow the method in the Gore and Gilet books (which I highly recommend if you don’t have them).  They stress the importance of a neck blank which is squared up on all faces.  The cut can be made with various types of saws but you won’t get a good joint with fresh sawn faces.  Clamp them side-by-side and clean up the faces together with a #5 or larger plane.  Then check flatness longitudinal and diagonal.  Finally, check on each piece that the line between the two faces (the flat face and the inclined face) is exactly 90 degrees to the sides.  If this is all good, you are ready to glue and clamp.  I am sure you already have a clamping method worked out.  It is certainly easier if you are working with flat and square boards.  As we all know, it can be a tricky joint to clamp because it wants to slide around on you.  G&G describe a nice trickto keep the 2 pieces still while assembling.  Clamp the long (neck) piece to the bench, standing on its edge.  Position the peghead side, also with its edge flat on the bench.  Place a block or something solid at the far end of the peghead piece so that it stops that piece from running away when you apply the clamps.  Get it all lined up and apply glue (I prefer Titebond rather than hide glue, for more open time) and then place non-stick cauls on the front and back faces and multiple clamps across the lot.  That is all I know.  

[Mac McElwain]

Yep - that's pretty much what I do, except that my order has been different. I will revise that. I very much like the look of the back strap and would like to try one. Could you share a bit more on how you do it? Cheers, MAC

[Mark McLean]

 A backstrap is often used for peghead repairs.  Our host Frank Ford has a good pictorial/tutorial at frets.com:

http://www.frets.com/FretsPages/Luthier/Technique/Structural/Broken...

(It is amazing to think he put that stuff up over 20 years ago - a real internet pioneer.  But I digress). In that example he is putting mahogany over mahogany and trying to make it invisible, but if you follow the same routine with a contrasting timber you can make a feature out of it.  I got this idea from Nigel Forster (check out his website for some inspiration), and Nigel describes it as being like how snooker cues are made.  There are interesting Youtube videos available of that too, and they will help you understand how to glue up flat layers and then carve them into a round shape for the final effect. So, if you are doing this on a neck blank under construction you can do it after the scarf joint, while the blanks are still flat.  The backstrap veneer is about 2.5 mm thick.  An offcut of side material works well.   Bend it on a hot pipe (a sharp crease, not a gentle bend), to match the angle of your scarf joint.  Glue it to the neck blank and then proceed to carve your curved neck profile.  You will carve off most of the backstrap material on the neck and only a thin tapering strip will remain in the centre.  You will need to adjust the overall thickness of the neck and peghead by taking some material off the front, so that it maintains your desired dimensions.  

[Mac McElwain]

Lovely - thanks. I was puzzled about how you matched it to the headstock angle. Now I'm not. Sounds like a good excuse to treat myself to a hot pipe! (I use a blanket for bending)

[Randall Curtis Bowman]

I've had luck bandsawing the joint, then cleaning up with sandpaper glued to a dead-flat surface. Once trued up, placing at least four brads on the outer edges prior to gluing will hold everything in place.  The initial bandsawing is not without risk, but excess length is allowed towards the heel;  then trimmed last. I drill holes for the brads using one for the bit. Just snip the head off. The headplate and backstrap will cover any errant holes, within reason.  Just a thought from an amateur.

[Mac McElwain]

Thanks Randall. The Brads thought is a really good one - reminds me of using brads at 1st and 11th frets to hold a fingerboard still during gluing. I'll use the idea

MAC

[Russell Vance]

Hi Mac. hi all.

Firstly,  in no particular order,  I use screws for locating stuff like scarf joints  (stainless steel long humbucker ring mounting screws or similar)  - this allows the glue joint to be slid back and forth to gain a better initial contact and grip and consistent glue thickness before getting the initial  clamp down done with screws locating the thing accurately and applying some pressure before the clamps are located..  The ever-essential brads do not allow this cabinet making process of sliding the glued surfaces.

Secondly, in the imagery of neck joint configs - number (1)  every time - you are gluing semi end-grain to long grain  which makes for a weak joint. The number 1 config when capped with a fingerboard gives you a "birds beak" joint and twice the gluing area or method 2.  Much stronger and when coupled with some short or full length carbon fiber reinforcements through the joint, which I believe is essential good practice, will give you half a chance if you drop the guitar on its head.  My thoughts on carbon fiber (or Titanium) are  that the only reason to not see it in necks is that it wasn't available or its too expensive or difficult for some.   But a neck break is never cheap so its a good investment in a quality instrument.  The added bonus of stability and strength is a given.

We glue scarf joints and center joints etc straight off the saw.  Its an Altendorf, but any well tuned quality platform with a large enough planer/finishing  style blade will do it. We keep my planes out in the kitchen to use as cheese graters.but occasionally I give them a run because  its a nice feeling taking a shaving offa an edge.

Its also debatable that scarf joints are stronger in some way than one piece cut billet.   Given that scarf joints are weaker by way of the end-grain gluing component and that a drop will stress a number (2)  joint in exactly the same way as a cut billet I'm not convinced that that a scarf joint provides anything other than a cheaper input cost.   

Most of what is here is drawn for experience with Electric Guitar building which sees additional operational stress being put on the joints from  various factors.  However,  the basics of sticking things together in the strongest possible manner are much the same.    

Regards, Rusty.