When professionals evaluate a used, pre-owned MOORE No. 3 Jig Grinder, they are not just buying a machine—they are acquiring a precision system capable of micron-level accuracy. This model, originally built by Moore Special Tool Company, remains a benchmark in coordinated hole grinding, toolroom precision, and aerospace-grade finishing.

Below is what experienced buyers understand—and what separates a good deal from a costly mistake.

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What Makes the MOORE No. 3 Special?

A jig grinder like the Moore No. 3 is designed for ultra-precision hole positioning and finishing, often achieving tolerances in the range of ±0.0001″ (≈2.5 microns) .

Key Professional Advantages:

• Extreme accuracy → superior to most milling/turning machines
• Air spindle technology → ultra-high-speed grinding (40,000–60,000 RPM)
• Coordinate grinding capability → ideal for dies, molds, aerospace parts
• Long lifespan → many machines from the 1960s–80s still outperform newer grinders

👉 This is why Moore machines are still widely used in toolrooms, aerospace, and precision mold industries.

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Technical Specifications (MOORE No. 3)

Below is a consolidated professional spec sheet (varies slightly by configuration and retrofit level):

Machine Capacity & Travels

• Table Size: 11″ x 24″ (280 x 610 mm)
• X-Axis Travel: 18″ (457 mm)
• Y-Axis Travel: 11″ (280 mm)
• Z (Spindle Vertical Travel): ≈3.6″ (92 mm)
• Table to Wheel Collet Distance: 2″ – 18″ (50–457 mm)

Spindle & Grinding Performance

• Main Spindle Speed: 25 – 250 RPM (variable)
• Grinding Spindle (Air Spindle):
  • Typical: 40,000 – 60,000 RPM
• Spindle Feed: 2 – 240 strokes/min (variable)
• Grinding Capacity: ≈1/64″ to 3.5″ bore diameter

Machine Construction

• Structure: Heavy-duty cast iron base
• Positioning Accuracy: Up to 0.0001″ (2.5 µm) capability
• Table Movement: Hand-scraped ways with precision lead screws
• Control: Manual (often upgraded with DRO or CNC retrofits)

Dimensions & Weight

• Approx. Size: 80″ x 65″ x 102″
• Weight: ≈3,800 – 4,000 lbs (1,700–1,800 kg)

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What Professionals Check Before Buying

1. Spindle Condition (CRITICAL)

• Air spindle is the heart of the machine
• Check:
  • Runout (micron level)
  • Noise/vibration
  • RPM stability
    👉 Replacement cost can exceed €5,000–€15,000

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2. Table & Ways Wear

• Inspect:
  • X-Y backlash
  • Table smoothness
  • Scraping marks (original vs worn)
    👉 Worn ways = lost accuracy (main risk in old machines)

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3. Alignment & Geometry

• Check:
  • Spindle perpendicularity
  • Table squareness
  • Circular interpolation accuracy
    👉 Even slight deviation kills jig grinding precision

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4. Accessories & Tooling (Hidden Value!)

Machines often come with:

• Air spindles (different speeds)
• Grinding arbors
• Radius attachments
• DRO systems

👉 These can add €5K–€20K hidden value

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5. CNC Retrofit Potential

Many professionals specifically buy Moore No. 3 for:

• CNC upgrades (3–5 axis)
• Achieving modern performance at low cost

Retrofit systems can reach:

• Positioning accuracy: 0.000010″ resolution

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Common Mistakes Buyers Make

• Buying without checking spindle → most expensive mistake
• Ignoring missing grinding head → machine becomes unusable
• Assuming all Moore machines are equal → condition matters more than age
• Overlooking power requirements (single-phase vs 3-phase)

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Real Market Insight (Used Machine Value)

Typical pricing range (depending on condition & tooling):

• Basic / incomplete: $… – $…
• Good working condition: $… – $…
• Fully equipped / retrofitted: $….+

👉 The real value is in precision + accessories, not just the base machine.

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Final Professional Insight

A used MOORE No. 3 Jig Grinder is not just a machine—it is a precision platform.

Smart buyers focus on:

• Spindle health
• Mechanical geometry
• Included tooling
• Upgrade potential

If these are right, you can acquire a machine capable of:
👉 Aerospace-level tolerances
👉 Mold & die perfection
👉 Long-term reliability