National Acme RAS-8 Multi-Spindle Automatic
Key Specifications
Number of Spindles
Maximum Bar Diameter
Spindle Speed
Drive System
Working Positions
Cross-Working
Overview
The National Acme RAS-8 is an 8-spindle cam-driven multi-spindle automatic screw machine produced by National Acme Company (now part of the Davenport-National Acme heritage). National Acme machines were American-made production workhorses in the post-war precision parts industry, competing with Davenport and Acme Gridley in the North American market. The RAS-8 processes bar stock up to 38 mm in diameter across 8 spindles, targeting medium-diameter turned parts in aluminum, brass, steel, and stainless steel. The machine features an overhead cam drum with replaceable cams for toolpath control, enabling complex profiles including step-turned shafts, threaded fittings, and multi-diameter connectors. National Acme machines are found in rebuild service at specialists throughout the North American machining industry and retain loyal users due to their robust construction and large tooling ecosystem. The RAS designation indicates the Ram-Actuated Spindle variant, with individually retractable spindles for back-face work.
Full Specifications
| Parameter | Value |
|---|---|
| Number Of Spindles | 8 |
| Maximum Bar Diameter | 38 mm (1.5 in) |
| Spindle Speed | Up to 3,000 RPM |
| Drive System | Overhead cam drum (mechanical) |
| Working Positions | 8 front + 8 back positions |
| Cross-Working | Cam-driven cross slides |
| Gear Quality | IT6-IT7 |
| Production Rate | Up to 100 parts/min on simple parts |
| Collet Type | Standard National Acme collet system |
| Bar Feed | Magazine bar feed compatible |
| Title | Home |
| Subtitle | No subtitle set |
| Description | Join Emerald Club and enjoy exclusive benefits including counter bypass, choose your own car and earn rewards towards free rental days (select locations). |
| Lazy Loading | Enabled |
| Cta Text | No CTA Text set |
| Model | RB-8 |
| Brand | ACME GRIDLEY |
| Type | Multiple Spindle Automatic Screw Machines |
| Spindle Hole Dia2625 Spindles8 Spdl | Dimensions4'8" x 13'2" x 8'Weight33,800 Lbs. |
| Spindle Hole Dia2625 | # Spindles8 spdl |
| Spindle Hole Dia | 2.625" |
| Spindles | 8 spdl |
| Dimensions48 X 132 X 8 | Weight33,800 Lbs. |
| Dimensions | 4'8" x 13'2" x 8' |
| Machine Weight | 33,800 Lbs. |
| Listings | (1) |
| Automatic Screw Machines Multi Spdl | 4 photos |
| Fp Miller Co420 Ingham Stjackson Michigan 49201united States | Oxford Gear Machinery425 Davison Lake RdOxford, Michigan 48371United States |
Specifications sourced from machinetools.com — verified 2026-03-28
Strengths & Limitations
Strengths
- Proven American-made construction with long service life
- 38mm bar capacity covers medium-diameter turned parts
- Large tooling ecosystem — National Acme tooling widely available
- Low acquisition cost on used market for high-volume dedicated programs
- 8-spindle configuration produces finished parts every cycle
Limitations
- Cam-driven — changeover requires cam replacement (hours, not minutes)
- No CNC — inflexible for variable geometry programs
- National Acme no longer manufactures — maintenance through rebuild specialists only
- Older machine technology requires operator expertise in cam-driven screw machine setup
Best For
Frequently Asked Questions
01
Yes. National Acme parts are available through rebuild specialists including National Acme Rebuild (a dedicated rebuild company) and various machine tool dealers who stock common wear parts. The large installed base supports an active parts market.
02
The RAS (Ram-Actuated Spindle) designation indicates that individual spindles can be retracted during the cycle using hydraulic rams, enabling back-face work without dedicated auxiliary spindles. This improves capability for parts requiring machining on both ends.
03
National Acme machines are generally considered more robust for heavy cuts on steel, while Davenport machines excel on lighter cuts in brass and aluminum at higher speeds. Both are capable for their intended applications with proper setup.
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