EZO HSA750 Hipshot A-Style Bridge Layout & Drill Guide

EZO HSA750 Bridge Layout & Drill Guide

Precision bridge placement, alignment, and drilling for the Hipshot A-Style .750" 4-string bass bridge.

Installing a bridge is one of the most critical layout operations in an instrument build. Centerline alignment, scale-length placement, intonation range, mounting holes, and string-through locations all need to agree before the first permanent hole is drilled.

The EZO HSA750 Bridge Layout & Drill Guide brings those critical references together into one purpose-built tool.

Designed specifically for the 4-string Hipshot A-Style Bass Bridge with .750" string spacing, the HSA750 assists with both X and Y bridge positioning, provides a dedicated intonation midpoint reference, and accurately locates the bridge mounting and string-through holes.

Instead of independently measuring every feature of the bridge, the HSA750 allows you to establish the important geometry directly on the instrument.

Establish the scale. Align the centerline. Position the bridge. Drill with confidence.

More Than a Drill Template

A bridge isn't correctly positioned just because its mounting holes are in the right place.

Its position must agree with the instrument's:

• Scale length
• Neck centerline
• String path
• Saddle position
• Available intonation adjustment
• Mounting-hole pattern
• String-through locations

The HSA750 was designed around those relationships.

Rather than simply reproducing the mounting-hole pattern of the bridge, the guide provides physical references that help establish where the bridge belongs on the instrument before those holes are ever drilled.

Two Axes. One Bridge Position.

The HSA750 incorporates two primary layout references that work together to establish bridge position.

Longitudinal Centerline — X-Axis Alignment

The centerline running lengthwise through the HSA750 provides a direct reference for aligning the bridge with the instrument.

This allows the guide to be aligned with your established neck and instrument centerline, helping ensure that the bridge follows the intended string path rather than simply referencing the outside shape of the body.

This is especially valuable during scratch builds, where there may be no existing bridge holes or factory references to work from.

Horizontal Reference Line — Intonation Midpoint

The horizontal reference line on the HSA750 represents the midpoint of the Hipshot A-Style bridge's available intonation adjustment range.

This is an important distinction.

The line does not simply represent an arbitrary edge or dimension of the bridge. It references the center of the saddle's available fore-and-aft adjustment.

That gives the builder a meaningful reference when establishing bridge position relative to the instrument's scale length.

Instead of measuring from the front or rear edge of the bridge—dimensions that have little direct relationship to the vibrating length of the string—the HSA750 lets you position the bridge according to the center of its usable intonation range.

This provides a repeatable starting point while retaining saddle adjustment in both directions for final setup and compensation.

Designed Around Intonation Adjustment

Proper intonation requires the bridge saddles to move.

That's why simply placing a saddle at the nominal scale length without considering its available adjustment range isn't an ideal way to establish the position of the entire bridge.

The HSA750 makes that adjustment range visible during layout.

By referencing the midpoint of the bridge's intonation travel, the builder can deliberately position the bridge while preserving usable adjustment for final setup.

The horizontal intonation reference and longitudinal centerline work together:

Vertical/longitudinal centerline:
Controls neck, bridge, and string-path alignment.

Horizontal reference line:
Identifies the midpoint of the bridge's intonation adjustment range.

Together, these references establish the bridge position along both axes before any permanent drilling operation begins.

Purpose-Built for the Hipshot A-Style .750"

The HSA750 isn't a universal bridge template.

It was engineered specifically around the geometry of the Hipshot A-Style 4-string bass bridge with .750" string spacing.

The bridge centerline, intonation midpoint, mounting-hole pattern, and string-through locations are incorporated into one coordinated layout system.

That means you don't need to independently establish each of those measurements or repeatedly reposition the actual bridge while marking the instrument.

Place the guide.

Establish your references.

Verify your layout.

Then transfer the geometry to the body.

Mounting Hole Layout

Once the HSA750 is properly positioned, the bridge mounting-hole locations can be transferred directly to the instrument.

This eliminates the need to individually measure the mounting-hole spacing or use the actual bridge as a drilling template.

It also means your finished bridge can stay safely on the bench while drilling, marking, and other potentially destructive operations take place around the instrument.

Because the mounting locations are referenced to the same centerline and intonation geometry used to position the guide, the entire operation remains part of one consistent layout.

String-Through Layout

Building a string-through-body bass?

The HSA750 also incorporates the corresponding string-through locations for the Hipshot A-Style bridge.

Because these locations share the same geometry as the bridge mounting pattern, centerline, and intonation reference, they remain aligned with the rest of the installation.

This gives you a single reference tool for establishing the bridge and transferring both mounting and string-through locations.

Built for Scratch Builders

The HSA750 is particularly useful when building an instrument from scratch.

There are no factory holes.

There is no existing bridge position.

There may not even be a finished body perimeter available as a reliable reference.

Instead, the instrument is built around established geometric relationships: the neck, scale length, centerline, string path, and hardware.

That's exactly where the HSA750 shines.

It provides a physical bridge-layout reference that works from the geometry of the instrument rather than requiring an existing instrument to copy.

Designed for the Shop

The HSA750 was developed as an actual working luthier tool—not simply a dimensional model of a bridge.

Its larger footprint provides useful reference surfaces for positioning and alignment while making the guide easy to handle and secure during layout.

Integrated reference lines communicate the important geometry directly on the tool, helping make the installation process easier to understand at the bench.

It is reusable, purpose-built, and designed to eliminate repetitive layout work.

It's the kind of tool we wanted on our own bench.

So we made it.

Features

• Designed specifically for the Hipshot A-Style 4-string bass bridge
• Designed for .750" string spacing
• Assists with X and Y bridge positioning
• Integrated longitudinal bridge centerline
• Horizontal reference line indicates the midpoint of the bridge's intonation adjustment range
• Helps establish bridge position relative to scale length
• Preserves usable saddle adjustment for final intonation
• Integrated bridge mounting-hole locations
• Integrated string-through-body locations
• Helps maintain neck, bridge, and string-path alignment
• Reduces repeated measuring and layout operations
• Eliminates the need to use the finished bridge as a drilling template
• Reusable across multiple builds using compatible hardware
• Designed for scratch-built and custom instruments
• Designed and manufactured by EZO Guitars in Vermont

Recommended Workflow

1. Establish the instrument centerline

Determine and clearly mark the centerline of the neck and instrument.

The bridge should ultimately follow the neck and intended string path—not simply the outside perimeter of the body.

2. Establish your scale-length reference

Determine the instrument's intended scale length and establish the appropriate bridge-position reference on the body.

3. Align the HSA750 centerline

Position the HSA750 so its longitudinal centerline agrees with the established neck and instrument centerline.

4. Position the intonation reference

Use the HSA750's horizontal reference line to locate the midpoint of the bridge's available intonation adjustment range relative to your scale-length layout.

5. Verify the complete geometry

Before drilling, verify:

• Neck alignment
• Instrument centerline
• Scale length
• Intended string path
• Saddle adjustment range
• Bridge orientation
• Mounting-hole locations
• String-through locations, if used

6. Secure the guide

Once everything agrees, secure the HSA750 so it cannot shift during marking or drilling. We highly recommend double-sided woodworker's tape.

7. Transfer the mounting locations

Mark or drill the bridge mounting-hole locations using the guide.

8. Transfer string-through locations

If building a string-through instrument, use the corresponding guide locations to establish the string holes.

9. Remove and verify

Remove the HSA750 and perform one final verification before drilling any remaining holes to their finished diameter or depth.

Measure twice. Verify the geometry. Then make chips.

Compatibility

Bridge Type: Hipshot A-Style Bass Bridge
Configuration: 4-String
String Spacing: .750"

The HSA750 is designed for this specific bridge configuration.

It should not be assumed compatible with other Hipshot bridge models, different string spacings, 5-string configurations, or third-party bridges that appear visually similar.

Hardware manufacturers may revise products over time. Always compare your actual bridge to the HSA750 and verify all dimensions before performing permanent drilling or routing operations.

What's Included

• 1× EZO HSA750 Bridge Layout & Drill Guide
• Quick-start installation guide
• Bridge positioning and alignment instructions
• EZO setup and best-practices documentation

Bridge, drill bits, clamps, and instrument hardware are not included.

Part of the EZO Builder System

At EZO Guitars, we don't think a good template should simply tell you where the holes go.

A good tool should help you understand why they go there.

The HSA750 was designed around that philosophy.

The centerline helps establish alignment.

The intonation midpoint helps establish bridge position.

The drill locations transfer the hardware geometry.

And the documentation helps explain how those references work together.

Our goal is to turn complicated instrument-building operations into understandable, repeatable processes—whether you're building your first instrument or your fiftieth.

Templates establish geometry.
Guides establish relationships.
Fixtures control the operation.
Knowledge brings it all together.

Born on the Workbench

The HSA750 wasn't created to fill a product catalog.

It grew out of an actual instrument build.

While developing and building instruments at EZO Guitars, we needed a better way to position and install the Hipshot A-Style bridge—one that accounted not only for mounting holes, but for centerline alignment, scale length, string-through positioning, and the bridge's actual intonation adjustment.

So we engineered one.

The resulting tool became the EZO HSA750 Bridge Layout & Drill Guide.

Now it's available for your bench.

Don't build alone.

EZO Guitars — Tools, knowledge, and open design for instrument builders.