Here’s a specialist’s, step-by-step guide to help you evaluate and choose a good used / surplus / second-hand / pre-owned Moore G-18 jig grinder (made in USA). It is built around risk mitigation, technical inspection, performance validation, and contractual protection.

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1. Know What You’re Looking At — Baseline Specs & Architecture

Before you make a trip, arm yourself with reference specs so you can spot deviations. Here’s what a typical Moore G-18 offers (or what sellers often list):

Parameter	Typical / Reference Value	Notes / Sources
Table size	11″ × 24″	Common spec for G-18 models
Table travel (X × Y)	18″ × 11″ (or similar)	Many listings for G-18 show this travel
Vertical spindle / head travel	~ 3-5/8″ quill + ~12-5/8″ vertical slide	Remanufacturing data lists these values
Table top to wheel collet	2″ (min) to 18″ (max)	Standard range seen in many specs
Spindle speeds / grinding wheel RPM	Variable head speeds (e.g. 9,000–40,000 RPM)	Some G-18 listings mention similar ranges
Spindle feed / cycles	~2 to 120 cycles per minute (or more)	Common feed spec in listings

If the machine you inspect deviates wildly from these (say, much reduced travel, incorrect spindle speed range, etc.), that’s a red flag you must explore.

Also, Moore (Moore Special Tool Co.) historically builds these in the USA; parts, spindles, and technical support often originate from U.S. supply chains.

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2. Pre-Visit Remote Screening

Before spending travel time or money, screen possibilities to eliminate weak candidates:

• Ask for complete spec sheets, serial number, build year, and photographs (interior, column, head, table, wiring cabinet).
• Request video of the machine running (axis motions, head travel, grinding spindle).
• Ask about recent repairs, spares replaced, maintenance history.
• Ask whether the seller allows a power-on test under your supervision.
• Check whether key spares (bearings, spindles, motor parts) are still available for that serial/model.
• Look at market listings / comparables (for example, used G-18 units going for some different prices in some markets)

If those remote signals are weak (missing docs, no willingness to power-on, vague answers), skip or negotiate hard.

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3. On-Site Inspection & Technical Audit

Once you get onsite, systematically walk through these checks. Use calibrated measurement tools (indicator, micrometers, test bars) wherever possible.

A. Structural & Machine Condition

1. Frame & Column Integrity
   • Inspect for cracks, weld repairs, distortions, or damage in the base, column, saddle.
   • Use a straightedge, surface plate, and precision rule to detect twist or warp.
2. Table & Slideways
   • Check the table for flatness, burrs, worn spots, or gouges.
   • Move the table cross and longitudinally by hand or at slow feed, listening/feeling for roughness, binding, or deviations.
   • Inspect the guide surfaces, wipers, lubrication points, and wear patterns.
3. Lead Screws / Nut Assemblies
   • Measure for backlash. Push-forward/backward in X and Y and record play.
   • Inspect screw threads for wear, signs of pitting, scuffing, or corrosion.
   • Check whether screws and nuts are adequately lubricated, and whether oil bath or drip lubrication (if present) is intact.
4. Vertical Slide / Quill / Head
   • Move the grinding head vertical slide and quill; look for stiction, uneven motion, or binding.
   • Measure alignment: check whether the spindle axis is perpendicular to table surface in multiple positions.
5. Spindle / Grinding Head
   • Mount a test arbor or collet, spin up to rated head speed, and measure runout (radial / axial) using dial indicator or better.
   • Listen/feel for noise, bearing wear, vibration.
   • Run for extended period and record temperature rise.
6. Table to Collet Distance / Travel
   • Confirm the distance range between table top and wheel collet (min to max) matches spec (e.g. 2″ to 18″).
   • Check that the head can move to extremes without collision or interference.
7. Spindle Feed / Cycles
   • Test the head’s feed / infeed movement or cycles (if equipped).
   • Ensure feed rate control is stable and responsive over full travel.

B. Electrical / Controls / Motors

1. Control Cabinet & Wiring
   • Inspect inside for burnt wiring, corrosion, overheated connectors, dust or moisture.
   • Verify proper wire routing, labeling, cable strain reliefs, shielding.
2. Drive Motors & Amplifiers
   • If servo or motorized axes are present, test drives for faults, noise, heating, and correct supply voltages.
   • Check motor nameplates vs expected voltage/phase (matching your shop).
3. Power-on Diagnostics & Controls
   • Power up the control / readout (if any).
   • Verify axis motion commands, limits, overrides.
   • Inspect error logs, alarms, diagnostic history.
4. Sensors, Limit Switches, Interlocks
   • Check limit switches for each axis and verify they trigger motion shutdown.
   • Confirm any safety interlocks, E-stop, door covers, etc. function correctly.

C. Functional / Performance Testing

1. Dry Motion / No Grinding Runs
   • Move axes through full travels without load. Listen for smoothness, clicks, stiffness, or deviation.
   • Cycle the head up/down, table traverse, full travel test.
2. Sample Grinding / Test Piece
   • Prepare a test workpiece (material and shape relevant to your future use).
   • Run a simple grinding operation (hole, face, or contour) and measure results: surface finish, dimensional accuracy, surface runout, concentricity.
   • Vary feed rates / infeed and examine whether quality remains consistent.
3. Stability Under Load / Extended Run
   • Run multiple cycles under load for 30–60 minutes. Monitor drift in dimensions, thermal growth, measure before/after for deviation.
   • Watch for control or mechanical backlash, drift, vibration.
4. Repeatability / Return to Zero Tests
   • Command the same position multiple times and measure positional deviation.
   • Check whether backlash compensation, zero-return behavior is consistent.
5. Extreme Position / Corner Case Test
   • Command the head and table to extremes (full reach) and test performance there.
   • Especially important on older machines.

D. Documentation, History & Parts

1. Machine Identity / Serial / Build Data
   • Verify the serial or model number, year of build, factory documentation if available.
   • Confirm any retrofit or rework history.
2. Maintenance / Repair History
   • Request logs of past repairs, replaced parts (spindle bearings, slides, screws, head rebuilds).
   • Look for gaps in logs (long unattended periods).
3. Spare Parts & Tooling Availability
   • Verify that critical spares (spindle bearings, motors, collets, control modules) are still available.
   • If the machine uses legacy or discontinued parts, understand procurement difficulty and lead times.
4. Refurbishment / Rebuilds
   • Check whether any major rebuild has been done (rewinding motors, regrinding slides, spindle rebuilds).
   • Inspect those repairs for quality — sloppy jobs may introduce misalignment.
5. Contract / Warranty / Acceptance Terms
   • Negotiate a conditional acceptance or holdback period after installation.
   • Insist on the seller guaranteeing certain performance specs (e.g. positional accuracy, spindle runout) under your test.

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4. Red Flags & Pitfalls to Avoid

Even if everything looks smooth at first glance, these issues can sink a deal later:

• Severe wear on slides, tables, or lead screws (hard to repair).
• Spindle bearings that rattle, overheat, or show excessive runout.
• Mechanical modifications or repairs that altered alignment (if not corrected properly).
• Missing or damaged control / electronics with no replacement path.
• Obsolete or unavailable parts particular to the G-18 model.
• Hydraulic / lubrication failure or neglect (if lubrication systems are faulty).
• Heavy corrosion, rust, or damage from environmental exposure.
• Poor wiring, dangerous modifications, or rewiring by amateurs.
• Seller’s refusal to allow a full performance test or to document parameters.
• No test parts, or inability to reproduce grinding performance.

If you spot any severe red flag without acceptable discount or remedy, either reduce your offer heavily or walk away.

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5. Acceptance Criteria & Decision Rules

Before you commit, set measurable thresholds you’re willing to accept. Some examples:

• Spindle runout (radial + axial) no worse than a few microns (as your process requires).
• Positional repeatability in X and Y within tolerance (e.g. ± 5 µm or better for your work).
• Table and head travel match spec closely (within a few percent).
• Sample grind results meet your required finish & dimensional tolerance.
• Performance under load remains stable over time (no drift).
• All safety and control features operate reliably.
• Cost of any remedial repairs / spares remains within your budget margin.
• Transfer of all documentation, spares list, manuals, and control parameters.
• Seller allows post-installation acceptance or holdback until tests passed.

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6. Logistics, Installation & Commissioning

Once you decide to purchase, ensure:

• You arrange proper rigging, lifting, crate/cradle support, and movement with care (these machines are precise and heavy).
• At site, level and align the base, grouting if necessary to reduce vibration and ensure stability.
• Calibrate axes, inspect alignments (table to head, head perpendicularity), check slides after settling.
• Re-run the same test parts to verify everything holds after relocation.
• Keep spares (bearings, collets, belts, wiring) on hand.