Description Colours Explained? Screw Heads Explained Threads Explained Specifications

Pickguard and Plate Screws for Fender® Guitars

Commonly known as “Pickguard Screws,” these are more accurately described as Pickguard and Plate Screws designed primarily for Fender® guitars. (Gibson® guitars rarely use #4 screws for mounting pickguards.)

Strangely, these are a "second" type of pickguard screw, which seems to be a proprietry design, specific to some (but not all) Fender® guitars - and, honestly? They're a bit of a nightmare to explain.

They're a #4 screw (in so much that they have a 3mm diameter thread) but they have a #3 head (at just over 5mm, where a #4 would be just under 6mm)

They're a bit of a funny one really - and there doesn't seem to be any hard and fast rule as to when and where they turn up, but they're weirdly common on production guitars (and they usually get replaced with straight forward #4 screws) - but, if you want to keep things original? And keep the heads in the slightly oversized counter sinks, as Fender® indended? these are the screws you need.

 

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Features

• Oval head design: fits into countersunk holes and sits slightly proud

• Made from mild steel

• Electroplated to match guitar hardware finishes

• Available in 13.5mm thread length

 

Gibson®, Epiphone®, Stratocaster® and Strat® are registered trademarks of Fender Musical Instruments Corporation and Gibson Musical Instruments Corporation. Axesrus® has no affiliation with FMIC

#4s vs #4s w/ #3 Heads

Honestly, I've absolutely no idea why anyone would come up with these screws - but, they do, definitely exist out in the real world, so, its worth while us stocking them.

Rather then using this section to demo where you can use them, as i have with the normal #4s, i'll show these screws against the "other" pickguard screws, then you can see what the difference is.

Colours

We know that for most people, when it comes to guitar parts, the usual palette is Chrome, Black, or Gold. But as you’ve probably noticed, there are quite a few more options out there.

To give you a better idea, here are some photos showcasing various common color finishes available.

Screw Heads Explained

Screws come with various head styles. Most people think of just two types — round head and countersunk — but there’s a bit more variety than that.

For now, I’ll focus on the most common styles you’ll find in wood screws.

Screw Gauges Explained

Screw Threads

Alright, let’s be upfront about this – I’m not a screw thread expert.

I trained as an electronics engineer, and these days I’m basically a glorified guitar tech. So if you’re looking for a deep-dive into screw engineering? I might not be your guy. But if we’re talking guitar screws? That, I’ve seen plenty of.

So, this guide is entirely based on what I’ve seen work in guitars. It’s not universal screw gospel – just one tech’s take.

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The Basics – Gauge vs Metric

Screws, much like wire (which I am more comfortable with), are made in two basic systems:

• Gauge (Imperial) – the older, slightly awkward system still commonly used for wood screws.

• Metric – the more straightforward system, which became the standard for machine screws and bolts.

And right away, that gives us our first headache.

Because while metric won out for machines and bolts, gauge sizes have stubbornly stuck around for wood screws – especially in guitars.

So when you're digging through scratchplate screws or bridge mounting screws – chances are, you're dealing with gauged wood screws, not metric.

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A Quick Note on Measurements

Yes, gauge screws are “Imperial” in origin – but I’m not. I think in millimetres, and I’ll be sticking with those for most measurements.

But don’t worry – I’ll include common gauge equivalents in both fractions and imperial decimals, just to keep everyone on the same page.

 

Screw Gauge	Head diameter (mm) Approximately	Shank/thread diameter (mm) Approximately
0000	2.74	1.37 (0.054″)
000	2.89	1.44 (0.057″)
00	3.04	1.52 (0.060″)
0	3.20	1.60 (0.063″)
1	3.35	1.67 (0.066″or 1/16”)
2	4.06	2.03 (0.080″or 5/64”)
3	4.77	2.38 (0.094″or 3/32”)
4	5.48	2.74 (0.108″or 7/64”)
5	6.19	3.09 (0.122″or 1/8”)
6	6.60	3.30 (0.136″ r 9/64”)
7	7.62	3.81 (0.150″)
8	8.33	4.16 (0.164″)
9	9.04	4.52 (0.178”)
10	9.75	4.87 (0.192″)
11	10.46	5.23 (0.206″)

Sizing Examples – Wood vs Metric

So, let’s say you need a wood screw with a 2.4 mm thread and a 4.8 mm head.

What you're after is a #3 screw.

Simple as that.

You’ll probably see it listed as:

• #3 x 25mm

• No.3 x 1inch

Same thing – a gauge 3 screw, just in different lengths depending on your needs.

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Metric Screws – Much Simpler

Metric screws are way easier to read.

They’re normally written as M followed by the diameter of the thread, in millimetres.

• M1 → 1 mm thread

• M2.5 → 2.5 mm thread

• M5 → 5 mm thread

• M3.5 → you guessed it, 3.5 mm!

At the risk of insulting your intelligence, here's a handy table:

M Number	Thread Diameter	Head Size / Spanner Size*
M2	2mm	4mm
M2.5	2.5mm	5mm
M3	3mm	5.5mm
M3.5	3.5mm	6mm
M4	4mm	7mm
M5	5mm	8mm
M6	6mm	10mm
M7	7mm	12mm

Limits and Head Size Weirdness

Both gauge and metric screw systems go way up into massive diameters – but we’ll keep things grounded in the realms of guitar hardware for now.

You might’ve noticed I included head size / spanner size in the table above. That’s generally useful if you’re dealing with hex head bolts…

But! That column becomes basically useless if you’re looking at other head styles.

Take the five different M3 screws I’ve got in front of me right now – fillister, hex socket cap, round, pan, and oval head. They’re all M3, but their head sizes vary by about 0.5 mm. There’s no standardisation across head styles.

I’ve no idea why the metric system didn’t lock down head diameters the way the imperial/gauge system did. But… it didn’t. So here we are.

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A Rough and Ready Rule

So, without diving into the deep end of screw classification – here’s a rule of thumb:

• If it’s a “proper screw” – meaning:

  • It’s pointy,

  • It’s going into wood,

  • It’s doing the work of holding timber together…

Then chances are very high that it’s an Imperial/Gauged screw.

Doesn’t matter where the guitar was made – US, Korea, Indonesia, Japan – wood screws = gauge sizes, almost universally.

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When Things Get Bolt-Shaped

Now, if you’re dealing with something that isn’t pointy – like a screw that threads into metal, plastic, or a pre-tapped hole – we’re in “bolt” territory.

(I know, guitars don’t use many true bolts, but you get me – screws that act like bolts.)

In these cases:

• Threaded inserts, like:

  • Humbucker legs

  • Humbucker bobbins

  • Bridge saddles

  • Truss rods

  • Nuts

You could be dealing with Imperial or Metric threads.

And here’s the kicker – there’s no consistent logic.

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Want an Example?

I’ve got:

• A box of #3 humbucker height screws → 2.4 mm diameter

• A box of M3 humbucker height screws → 3.0 mm diameter

Both made in the same factory.
Both found on Epiphone Les Pauls over the years.

So… which is right?

Answer: yes.

They both are. And that’s the frustrating part – even big names like Gibson® and Squier® mix and match Imperial and Metric threads depending on the model, year, and even the batch.

I’ve seen metric threads on Gibsons, and imperial threads on Squiers made entirely in metric-tooling factories. There’s no reliable pattern.

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The Only Real Advice?

Learn how to measure screws.

Seriously – a good pair of digital calipers will save you hours of trial and error. They’re cheap, accurate, and easily precise enough for guitar tech work.

 

What Does UNC / UNF / Coarse / Fine Mean?

This doesn’t really come up with wood screws – but the terminology is still valid.

That said, no one really bothers to measure it when dealing with wood screws. Why?

Because:

• Wood screws are cutting their own thread into the timber as they go.

• You’re not mating them to a pre-threaded hole.

• So whether the thread is a bit coarse or a bit fine – it doesn’t really matter.

But when you get into the world of machine screws and bolts, thread pitch becomes critical.

Why?

Because now, your male and female parts need to mesh perfectly. If the threads don’t match, you’re either stripping the hole, damaging the screw, or it just won’t go in at all.

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UNC vs UNF (Imperial System)

In the Imperial (or Unified Thread Standard) world, you’ll see:

• UNC – Unified National Coarse

• UNF – Unified National Fine

They refer to how tightly spaced the threads are:

• Coarse (UNC) → Fewer threads per inch.

  • Stronger in soft materials.

  • Easier to assemble.

• Fine (UNF) → More threads per inch.

  • Stronger hold in hard materials.

  • Less likely to loosen under vibration.

You’re unlikely to come across these markings on guitar parts unless you’re digging into something unusual like an old-style truss rod nut or a boutique bridge post, but they do exist in some areas of hardware.

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Metric Threads – Much Simpler

Metric wins the simplicity prize here again.

Metric threads are specified with pitch, and pitch is just the distance between the peaks of each thread, measured in millimetres.

For example:

• M3 x 0.5 means:

  • 3 mm thread diameter

  • 0.5 mm between each thread

Like with UNC/UNF, metric also comes in:

• Coarse pitch (standard unless otherwise noted)

• Fine pitch (less common – usually explicitly stated)

So:

• M6 x 1.0 → coarse (standard)

• M6 x 0.75 → fine thread

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So, What Do You Need to Know?

• If you’re messing with wood screws, don’t sweat thread pitch too much.

• If you’re dealing with a machine screw, bolt, or anything that screws into metal or plastic, pitch matters.

• Imperial hardware? You might see UNC or UNF – try not to mix them.

• Metric? Easy – just check the pitch, usually written right there in the size.

 

Diameter	Coarse Pitch	Fine Pitch
1	0.25	0.2
2	0.4	0.25
2.5	0.45	0.35
3	0.5	0.35
3.5	0.6	0.35
4	0.7	0.5
5	0.8	0.5
6	1	0.75
7	1	0.75
8	1.25	1 or 0.75

Metric Threads – Lovely, But Still a Bit Silly

Now, I’ll be honest – I love the metric system. It’s clean, logical, easy to understand, and in most situations, it lets us be far more precise.

But even I’ll admit – measuring the gaps between threads (that is, the pitch) is... stupid.

Thankfully, in the world of guitars, it doesn’t come up that often. That’s because we’re usually limited by what the screw is intended for – not some abstract engineering spec.

For example:

• M3 humbucker pole screw? → Coarse pitch (standard M3)

• M3 humbucker height screw? → Fine pitch (yes, really)

And yeah, that’s a bit silly – but since you’d never use one for the other (wrong length, wrong function, wrong everything), it sort of works itself out.

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Imperial Threads – A Bit More Fiddly, But Surprisingly Sensible

Imperial (Unified) threads follow a similar naming system, using:

• UNC → Unified National Coarse

• UNF → Unified National Fine

• UNEF → Unified National Extra Fine (you’ll never see this on a guitar)

Now, instead of measuring the gap between threads like metric, Imperial pitch is based on:

How many threads there are per inch of screw length.

So, say you’ve got a screw that has a 1-inch threaded section, and you count 40 threads across that inch?

That's 40 threads per inch, or 40 TPI.

Measure the outer diameter of that thread – let’s say it’s 3.175 mm (which is ⅛" or roughly #5 gauge) – and now you’ve got:

#5-40 UNC

• #5 = Gauge

• 40 = Threads per inch

• UNC = Coarse thread (because 40 TPI is coarse for a #5)

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Wait, That Sounds Complicated…

And yeah, it can be. But the Imperial system, weirdly, knows its own limits.

Here’s the nice bit:

• For most screw gauges, there are only one or two standard thread pitches.

• For example:

  • #4 screws? You’ll see them in #4-40 (UNC) or #4-48 (UNF)

  • #6 screws? #6-32 (UNC) or #6-40 (UNF)

So for guitar work?

You can mostly ignore pitch, because:

• It’s baked into the gauge.

• You’ll pretty much only ever see the correct pitch for the given gauge.

And wood screws? They might technically fall into UNC/UNF sizing, but in reality – they don’t follow those rules, and nobody measures them that way. Their threads are made for cutting into wood, not mating with pre-cut threads, so standardisation doesn't matter nearly as much.

Gauge	UNC	UNF
No. 0	N/A	80 TPI
No. 1	64 TPI	72 TIP
No. 2	56 TPI	64 TPI
No. 3	48 TPI	56 TPI
No. 4	40 TPI	48 TPI
No. 5	40 TPI	44 TPI
No. 6	32 TPI	40 TPI
No. 8	32 TPI	36 TPI
No. 10	24 TPI	32 TPI
No. 12	24 TPI	28 TPI

And that about covers threads I think, atleast in the ideal – wood screws are much simpler then machine screws/bolts, and if you’re working with “bolts” , a set of digital callipers and an imperial thread gauge are really helpful to figure out what your need.

Guitars Are Weird

Let’s be honest — guitars are weird.

Now, this probably isn’t just a guitar thing. I’m sure carpenters, joiners, aircraft fitters, nuclear engineers, and model railway enthusiasts all over the world would say the same about the screws they deal with daily.

These measurements — these tidy little “truths” about screw threads and standards — are all great in theory. But in the real world?

• I’ve never seen an M3 screw that actually measures 3.00 mm.

• I’ve never seen a #4 screw with a 3.09 mm thread and a 5.48 mm head.

It’s all very precise on paper — but guitars? They just don’t need screws to be that exact.

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“Close Enough” Is Usually Right

So, if you’re measuring a mystery screw and trying to figure out what size it is, remember:

Close enough is probably good enough.

Example:

You measure a wood screw and get 2.1 mm thread diameter, with a 3.9 mm head.

That doesn’t match the official spec for a #2 screw exactly…
But it’s clearly not a #1, and it’s not a #3 either.
And the chance of it being a metric wood screw? Almost zero.

So… it’s probably a #2.

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The Great Factory Curveball

All that theory I’ve written above?

• Wood screws = Imperial

• Machine screws = Metric or Imperial

• Imperial = Gauge + TPI

• Metric = Diameter + Pitch

It’s all true, and widely accepted across engineering and manufacturing.

Except — and here’s where it gets fun — screw factories didn’t get the memo.

The small, specialist factories making guitar screws?

They only speak metric.

Even if the screw should be a #3, it’ll often be invoiced as 2.5mm, or M2.4, or even just 2.6mm pan head, depending on what mood the production team were in that day.

It’s not that they’re wrong — it’s just that Imperial sizing is such a foreign concept in places like China, Japan, and Korea, that it’s easier for them to round everything to metric.

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A Real-World Example (a.k.a. Why I Drink Tea Before Opening Screw Deliveries)

Sitting on my desk right now are four boxes of screws — all meant to be #3s.
They’re all 2.4-ish mm in diameter. They all have heads around 4.2 mm.
They’re the same screw, for all practical purposes.

But here’s what the invoices say:

• 2.5mm – PSH Countersunk

• 2.6mm – P90 Pan Head

• M2.4 x 30mm – Humbucker height screw

• #3 x 1.23” – Oval Head

Same sizes, officially, but, four different descriptions. Because at factory level, everything gets metric-ified, and as soon as we convert, we introduce errors... essentially.
No one’s worrying about matching it to a TPI chart or a gauge system from a century ago.

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So… What Do You Actually Do?

Thankfully, in the real world, it’s not quite so mad.

Once you figure out:

1. Is it a wood screw or a machine screw?

2. Is it going into timber, metal, or plastic?

3. Is it probably Imperial or Metric, based on the guitar/part?

You can usually narrow things down quickly and confidently.

Threads and Heads Are (Almost Always) Over or Undersized

I touched on this earlier — but let me double down on it:

Screws, nuts, bolts, threads, heads — they’re rarely the exact size they’re supposed to be.

They’re close enough that it almost never matters in practice…
But trust me — the factories making guitar screws are not working to the kind of tight tolerances you or I might expect.

And you know what?

They’re right.
We’re wrong.

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Metric Screws – The “Nominal Size” Lie

When you see a metric screw labelled as M3, M4, or M5 – the “M” stands for nominal diameter. That’s the theoretical, “on-paper” measurement.

But in reality?

• An M3 screw might measure 2.8 mm across the male thread.

• An M5 might come in around 4.75 mm.

• On the female side (like nuts or threaded holes), they’ll usually be slightly under the nominal too.

So don’t expect your calipers to read a perfect 3.00 mm on an M3 screw.
Undersized male threads and oversized female threads are completely normal – especially in the guitar world.

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Imperial Screws – “Ballpark” Is the Name of the Game

Imperial sizing isn’t much more precise, to be honest — and that’s fine.

Because most of these small screws are being converted to metric somewhere along the supply chain, it’s not uncommon to see things like:

• 2.6 mm screw listed on a packing slip

• Even though 2.6 mm isn’t a standard gauge or metric size

And here’s the twist:

It might actually be 2.6 mm!

But in reality? That’s probably just a #3 screw with a slightly fatter thread.

And if it’s only 0.2 mm out? That’s well within the “don’t worry about it” zone.

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So What Should You Do?

Knowing your screw gauges is a fantastic starting point.
But when in doubt?

Check the actual dimensions.

We list the most accurate, real-world measurements for every screw we stock right under the Specifications tab.

No guesswork, no conversions, no theory — just the numbers that matter when you’re holding a guitar and trying to make something fit.