2. Mounting the Spindle (65mm vs 80mm)

Proper spindle mounting is critical to machine performance.

A poorly mounted spindle can introduce:

Vibration
Runout
Poor surface finish
Premature bearing wear
Z-axis binding

This article focuses strictly on mechanical mounting.
No wiring or programming is covered here.

Step 1 — Identify Your Spindle Diameter

PwnCNC spindles come in two body diameters:

Spindle Type	Diameter	Typical Collet
1.5kW ER11	65mm	ER11 (¼" max)
1.5kW / 2.2kW ER20	80mm	ER20 (½" max)
ATC ISO20	80mm	ISO20 taper

You must use a mount that matches your spindle body diameter.

📷 Photo Suggestion:
Side-by-side image of 65mm vs 80mm spindle bodies with caliper measurement shown.

Step 2 — 65mm vs 80mm Mounting Differences

65mm Spindles

Lighter weight
Lower torque
Typically direct-fit for many hobby CNCs
Smaller clamp surface area

Mount must fully contact the spindle body across the entire clamping surface.

80mm Spindles

Heavier
Higher torque
Greater cutting capability
Larger clamping area

80mm mounts provide more surface contact and increased rigidity.

Most customers upgrading from palm routers will move to 80mm.

Adapter Plates (When Required)

Some machines require an adapter plate between the Z carriage and the spindle mount.

An adapter plate is needed when:

Your machine’s bolt pattern does not match the spindle mount
You are upgrading from 65mm to 80mm
Your factory mount is integrated into a proprietary bracket

An adapter plate does NOT:

Add rigidity by itself
Correct misalignment
Compensate for poor mounting surface flatness

It simply allows proper bolt pattern alignment.

📷 Photo Suggestion:
Rear view of adapter plate mounted to Z carriage with spindle mount attached.

Clamping Philosophy (Important)

Spindles are precision cylindrical bodies.

They are not meant to be crushed.

Follow these principles:

• Tighten evenly across all bolts
• Increase torque gradually
• Do not overtighten one side first
• Do not use threadlocker on clamp bolts

The goal is uniform compression — not maximum force.

If you visibly deform the mount or struggle to close the clamp, you are applying too much torque.

Over-tightening can:

Distort the spindle housing
Reduce bearing life
Cause noise at high RPM

A firm, even clamp is sufficient.

Alignment Principles

The spindle must be:

• Fully seated inside the mount
• Flush against the back of the clamp
• Vertically straight relative to the Z plate

Before tightening fully:

Lightly snug the bolts.
Verify the spindle body is not tilted.
Ensure the mount is square to the Z carriage.
Then tighten evenly.

If your Z plate is not square to the gantry, correct that first.

Do not attempt to compensate with clamp pressure.

Z-Travel Considerations

Spindles are taller and heavier than trim routers.

Before final tightening:

• Raise the Z axis fully.
• Confirm the spindle clears the gantry.
• Confirm motor cable clearance at top travel.
• Check lowest travel point does not bottom out before reaching spoilboard.

If you are switching from a router to a spindle:

You may lose some upward Z clearance.
You may gain cutting depth due to longer body.

Plan accordingly.

Weight Considerations

Approximate weights:

Spindle	Weight
65mm 1.5kW	~6–7 lbs
80mm 1.5kW	~11–12 lbs
80mm 2.2kW	~13–15 lbs
80mm ATC	~18–22 lbs

Heavier spindles increase Z-axis load.

Ensure:

Your Z assembly is rigid
Linear rails are clean
Leadscrew/ballscrew is properly tensioned

ATC-Specific Clearance Notes

(ATC systems only)

ATC spindles require additional clearance for:

• Tool holder insertion height
• Pneumatic fitting clearance
• Dust boot compatibility
• Tool rack alignment

You must ensure:

Adequate clearance above the spindle for tool changes
Tool rack positioning does not interfere with gantry motion
Dust boot does not obstruct tool pickup path

Do not permanently mount tool racks until:

The machine is fully assembled
Tool change dry runs are completed

📷 Photo Suggestion:
Side view of ATC spindle showing extra height compared to manual spindle.

Before Moving On

Once the spindle is:

Properly mounted
Evenly clamped
Verified for clearance
Z-axis tested manually

You may proceed to:

➡ Cable Routing & Strain Relief

Do not apply electrical power yet.

Mechanical setup should be fully complete before wiring begins.