When considering the purchase of a used or surplus Cincinnati 107-4 centreless grinding machine (made in USA), smart engineers will run through a detailed assessment across four phases: documentation review, physical & mechanical inspection, performance testing & part-availability check, and commercial/installation considerations. Given the age and complexity of centreless grinders, particularly from legacy manufacturers, this assessment is critical to avoid unforeseen costs and performance issues.

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1. Documentation & machine history

Before stepping onto the shop floor, you want as much information as possible. Key items to request:

• Serial number, build date, original spec sheet/manual. For example the 107-4 service manual is available.
• Service history: how many shifts it ran, maintenance records (wheel maintenance, dressing, lubrication, hydraulic system), any major rebuilds.
• Crash or damage history – e.g., damage to datum surfaces, frame, regulating wheel base.
• Grinding wheel/spindle history: check if grinding wheel spindles (and regulating wheel spindles) have been rebuilt or replaced.
• Current tooling/accessories: rest blade, regulating wheel gears, wheels, automatic feeding system, safety guards, dust/filtration system.
• Spare parts list and known issues for the model – for example parts list for 107-4 exists.
• Availability of CAD/drawing/layout for installation, and details of previous machine alignment, set-up.

Why this matters:
Centreless grinders are precision machines with many interacting components (main grinding wheel, regulating wheel, feed mechanism, rest blade, dresser, hydraulic/pneumatic systems). Without good history you risk inheriting latent problems.

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2. Visual & mechanical inspection

Once you are on site (or doing a live-video inspection if remote), conduct a thorough walkthrough.

2.1 External & structural condition

• Look for corrosion, pitting or damage on bed surfaces, wheel guard frames, work‐rest base and regulating wheel support.
• Inspect the work‐rest blade mounting surface, the rest blade itself for unusual wear or chipping.
• Check the regulating wheel assembly for gear backlash, bearing noise, proper mounting.
• Inspect the wheel spindle housings (main spindle & regulating wheel spindle) for oil leaks, seal damage, excessive oil film or grit buildup.
• Check that the machine’s sub-systems (coolant tank, dust extraction/chip conveyor, guarding, electrical cabinet) are present and functioning.
• Inspect the condition of wheels – main grinding wheels should show no major cracks; check for proper wheel flange alignment, look for any repair or “glue up” of wheels.
• Confirm that the bed/cradle is still rigid and properly supported. Any sagging, cracked welds or improper leveling are red flags.

2.2 Mechanical & operational checks

• Rotate the main wheel spindle by hand (and power-on if safe) to listen for bearing noise or vibration.
• Similarly rotate the regulating wheel spindle. Feel for smooth motion and absence of play/backlash.
• Check the feed mechanism: work‐rest feed, regulating wheel feed, power feed engagement/disengagement. Look for smooth traverses, no binding.
• Check hydrau­lic/pneumatic systems: e.g., feed pressure, brake systems, rest blade elevation, safety stops.
• Check machine alignment: measure runout on work‐rest blade, check regulating wheel runout, verify relative geometry between rest blade and wheel.
• Check machine controls: If digital readouts or automation exists, test for correct function; if manual, check the condition of handwheels, stops, and feeds.
• Check coolant system: Inspect coolant tank for debris, sludge, rust; check condition of lines, pump, filters, chips removal. Good maintenance history of coolant is vital.
• Check adequacy of dust/filtration system: many older machines suffer from poor coolant/dust management causing bearing and slide wear.

2.3 Precision & wear measurement

• Measure dressing head runout and wear – ideally the dresser is in good condition.
• Use an indicator to check vertical and horizontal axes for straightness and repeatability across the table/work rest area. If possible check work‐piece geometry: e.g., grind a sample bar and measure diameter and roundness.
• Check thermals: run the machine warm, and monitor stability of wheel spindle and regulating wheel speeds, check for thermal drift.
• Check worn parts: For example rest blade wear plate, regulating wheel bearings, spindle bearings, feed screws, bedways. Ask for spare part cost if major wear is found.

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3. Matching to production environment + parts/upgrade availability

• Workpiece compatibility: Confirm the 107-4’s capacity (max diameter, length, throughput) meets your part specifications – legacy spec sheets show 14″ wheels, 9″ diameter wheel, 4″ work rest body.
• Tooling/consumables: Availability and cost of rest blades, regulating wheel bearings, wheel spindles, dresser heads – older models may have limited parts.
• Controls and retrofit: If the machine is older manual type, check whether you’ll need automation or retrofitting (CNC feed, automatic loading/unloading). Budget for that as part of cost.
• Support & service: Check whether there are service providers for Cincinnati grinders in your region, and the availability of parts. For example maintenance guidance for Cincinnati grinders exists.
• Installation & site readiness: Centreless grinders often need robust foundations, proper coolant and filtration systems, and precise alignment. Check shop floor suitability, power, air supply, dust extraction, chip removal, vibration isolation.
• Throughput vs downtime risk: Older machines like this might offer lower cost but if downtime risk is high or precision compromised, cost of rework/downtime may outweigh savings.

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4. Commercial & contractual considerations

• Benchmark price: Investigate recent used selling prices for 107-4 machines to benchmark. (Listings exist online.)
• Condition-based negotiation: If inspection reveals major wear (spindle rebuild needed, bed alignment questionable, significant parts missing), adjust price accordingly.
• “As-is” vs warranty: Many used machine sales are “as-is”. Negotiate at least a short trial/inspection window after delivery or include condition acceptance criteria.
• Transport & installation cost: Dry‐fit costs, rigging, machine leveling/alignment, test loads – these can add 10-20% or more of the list price.
• Machine availability lead-time: If machine needs disassembly or parts ordered, factor into project schedule and cost-of-delay.
• Documentation and compliance: Ensure you receive complete manuals (operations, parts lists), wiring diagrams, and comply with any local safety/emissions requirements (especially if moving from US to other jurisdiction).
• Hidden costs: Spare wheel sets, dressing stones, fresh coolant, filtration media, hydraulic fluids, electrical upgrades – build a contingency.

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5. Deal-breaker / high-risk red flags

• Significant spindle bearing noise or excessive run-out – very expensive repair.
• Damaged or missing work‐rest blade support or severely worn rest blade plate.
• Regulating wheel assembly with excessive backlash/noise – impacts part quality.
• No history of coolant or dust management – can mean hidden wear on bearings/slides.
• Absence of wiring/manuals or missing core components (e.g., feed drives, automation) – may inflate cost later.
• Foundation or bed misalignment beyond acceptable limits – leads to poor accuracy.
• Parts unobtainable or support network nonexistent – high risk of extended downtime.

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Summary Checklist

Before signing the deal, confirm:

• Serial/build date, service history, crash/repair history.
• Machine externally clean, structurally sound, spindles smooth.
• Feed/traverse systems functioning, coolant and dust systems good.
• Precision measurements confirm acceptable geometry and run-out.
• Spare parts availability and retrofit support verified.
• Full cost of purchase + transport + installation + spare parts considered.
• Contract terms clear (inspection window, as-is vs warranty, acceptance criteria).