Worn ACME Lead Screw on a Cincinnati Monoset?

The ACME lead screw and bronze nut on a Cincinnati Monoset wear with decades of use — backlash creeps in, the slide loses precision, and replacement parts are long out of production. Here is where machinists actually go to fix it.

On a worn Monoset, the usual symptoms are excess backlash in the wheelhead feed and inconsistent positioning. The wear is almost always in the ACME screw, the mating bronze nut, or both. You have three realistic paths: recondition the existing screw, source a remanufactured part, or have a new nut/bushing made. The shops below cover all three.

Shops that can help

Triple R Systems

Remanufactures Cincinnati Monoset tool & cutter grinders and supplies replacement parts — a first call for Monoset-specific components.

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Barnes Industries

Reconditions worn ACME and trapezoidal lead screws — re-cuts the thread form and restores fit, often cheaper than sourcing new.

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GCH Tool Group

Stocks Cincinnati / Milacron grinder spare parts and components.

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Cincinnati Machines (cinmac.com)

The current Cincinnati Machines brand — Monoset/Monaset parts, manuals, and support.

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Shop tip: A common shop fix is making a new bronze nut or threaded bushing to match the existing screw — search the Practical Machinist forum for "Monoset lead screw" write-ups before you spend on a full rebuild.

While you've got it apart…

Dull HSS drills slowing the job down? We resharpen them by mail — flat-rate, fast turnaround, from our shop in Perry, OK.

Ship your drills →

Know a better shop?

Talk it through with other machinists on the MachinistPost forum — real shops, real experience.

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MachinistPost is not affiliated with the companies above and earns nothing from these listings — we list shops we believe can help based on public information. Always confirm capability, pricing, and turnaround directly before sending work.