neck installation - drilling holes

[Jean-Philippe Regnard]

Hi everybody,

i'm building my own electric guitar. I have some questions about neck installation, especialy for the drilling.

1- for the solid body, i have to drill the holes larger than the screws but how many?

2- for the neck it's the inverse, i have to drill holes (to avoid wood rupture) smaller than the screws but how many? 

Thank you for you answers.

[Barry Daniels]

The best way to determine this is to make some holes in scrap wood to find what works for your specific screws and wood. The body holes should just be large enough for the screw to pass through without the threads engaging. The neck holes should be small enough to get a really good grip on the threads, but large enough to allow you to install the screws easily and not stripping the head or cracking the wood. A little beeswax on the threads will help during installation of the screws

[Mark Wybierala]

There are screw drilling guides available if you search google. Here's one:

https://diy.stackexchange.com/questions ... t-diameter

Top top chart shows the recommended screw hole for the screw to bite and hold in the wood and the chart below it shows what size hole the screw can rotate freely in. Generally these charts are a good idea but like Mr Daniels says, Its good to test on scrap and use a lubricant on the screw. If you don't have beeswax, you can drag the threads of a screw across a bar of soap. Buy good screws and not ones from Walmart.

When drilling holes for a bolt-on neck, I like to use a couple of cauls, clamp the neck in place and temporarily install the first and last strings to line up the neck correctly. If this isn't possible due to your sequence of building, you can use string or thread to simulate your string lines.

[Chris Richards]

Usually in a Fender guitar the neck screws do bite in the body by a fraction, some neck screws are threaded all the way to the head and in which case I would drill the clearance hole 0.5mm smaller than the outside diameter of the thread, if the screws have a shank (unthreaded part) then drill the hole a fraction bigger than this diameter, for the holes in the neck measure the diameter of the screw at the root of the thread and the hole should be a fraction smaller than that. Screwing in to a hard maple can be difficult but DON'T be tempted to force the screw you'll end up breaking it, in which case drill a slightly larger hole. Also lubricate the screw with soap or a white grease that makes it A LOT easier to fit.

[Barry Daniels]

That goes against everything I know about screws. If the threads are biting into the first layer of wood then there will be no clamping action in the second layer.

[Peter Wilcox]

That goes against everything I know about screws. If the threads are biting into the first layer of wood then there will be no clamping action in the second layer.

I agree. I make the body holes just slightly larger than the thread diameter. That also provides a (very) little wiggle room to make sure the end of the neck is tight against the pocket (by slightly loosening the screws when the guitar is strung up to pitch and re-tightening.)

[Steve Sawyer]

Think about installing threaded inserts into the neck. Not a requirement by any means, but I always figure that anything that is designed to be screwed together, and has need of being disassembled and re-assembled can benefit from bolts and threaded inserts.

Also, I agree with Barry - there should be no engagement between your screws and the body holes.

Finally, what you're asking is the size of the "pilot hole" in the neck that is a) small enough to allow the screw threads to fully engage and b) large enough to not "bottom out" in the gullets between the screw threads, which can make the screws too tight and risking snapping the screws off while inserting them. The advice re waxing the threads is a good idea. Personally, I use a small dab of paste wax; it's easier to apply and sticks to the threads. Beeswax is "dry" and will fall off the threads, although it works fine if you warm the threads with a lighter or something so that the beeswax melts a bit onto the threads.

There are well-established guidelines for pilot hole sizes. They are determined by a) the number size of the screw (#8 or #10 is common for neck screws) and b) whether you are screwing into hardwood or softwood. Print this out, laminate it and hang it on the wall!

Everything we use for guitars is pretty much hardwood. I pulled a bunch of info together for this chart which shows the actual size of the screws (so you can determine what you have in your hand with some calipers) and the size of the pilot hole. If you have tapered drills which are specific for drillling pilot holes for wood screws, use them. If not, straight bits are fine, but more likely to need that wax depending on how hard the wood is and how tight you're trying to make the hole.

[David King]

I'd suggest skipping the threaded brass inserts which are quite difficult to install correctly and are prone to failure if not installed perfectly. Rather use a 10-32 or M4x.7 machine screw and "bottoming" tap. Outer of diameter of a 10-32 screw is nominally .190" but a 3/16" drill will get you close enough with a little soap on the threads. A #24 drill is ideal for 100% thread depth in a maple neck but a 5/32" drill will get you to 75% thread depth which is plenty strong enough for neck bolts. Just 1/2" of threads in maple will not strip out before the bolt breaks first (at around 950 pounds per screw). No wood screw can come close to that holding power.

[Steve Sawyer]

I've never done a neck mount as David describes, but I can attest to the strength of threads in wood. I see no reason why that would not be a first-rate solution.

One suggestion is that you clamp the neck into the neck pocket, and drill through the body into the neck with whatever size drill you use for the neck. You can then go back and enlarge the holes in the body using the existing holes as a guide. This ensures that the holes line up perfectly.

If you're using a plate on the body (as is common on Fender-style guitars) you can place your holes accurately by sticking the plate onto the body with some double-sided tape, and marking the hole centers by using the plate as a guide to center-punch the drilling points in the body. Use a drill bit that most closely fits the holes in the plate and give it a tap to mark the center. If you have a set of transfer punches (cheap and a good investment - paid less than $15 for my set on Amazon), they're even better. Best is if you have a "vix" bit which will self-center in the mounting holes in the plate, but usually don't drill deep enough to go through the body (they're primarily made for drilling holes for hinge mounting screws) so they'll just give you a good guide hole to start your drilling. Also, if you don't have a drill press, one of these is indispensable to keeping the drill square to the back of the body