Identifying South Bend and Logan Lathes by Serial Number

Overview

South Bend and Logan are two distinct American lathe manufacturers whose products are frequently confused in the secondary market because Logan built private-label machines for Montgomery Ward under the Power-Kraft brand and supplied turnkey components to other resellers. A bed with no cast-in nameplate, only a stamped serial number at the front of the bed, is therefore not necessarily a copy or a counterfeit; it is often a Logan-built Wards Power-Kraft, a Logan-built contractor-supplied machine, or a wartime Logan-branded lathe shipped directly to a government buyer. Correct identification requires correlating the serial number against the Logan production records, the headstock casting details, and the drive configuration rather than relying on the absence of a nameplate.

This reference documents the field-identification procedure used to differentiate South Bend, Logan-branded, and Wards Power-Kraft lathes from the 1930s through the late 1940s, when the highest overlap in parts, dimensions, and serialized casting numbers occurred.

Manufacturer History and Brand Relationships

South Bend Lathe Works operated in South Bend, Indiana, and is the direct ancestor of today's South Bend Lathe corporation. Logan Lathe Company, Inc., based in Beaver Falls, Pennsylvania, was a separate manufacturer that produced its own line of metalworking lathes while simultaneously supplying private-label machines to large catalog retailers.

The principal overlap relevant to identification is:

• Wards Power-Kraft — Montgomery Ward's house brand of machine tools. Power-Kraft lathes were Logan-built units rebranded with Wards castings and decals. The serial number sequence is shared with the Logan production line.
• Logan-branded production — Sold under the Logan name through industrial distributors and direct factory sales. Logan-branded serial numbers in the cited example start at approximately 10,100.
• Government and contractor supply — Logan supplied lathes directly to federal buyers (e.g., U.S. Army Corps of Engineers) during the World War II production era. These units are Logan-built and Logan-serialized but rarely carry Logan decals on the castings.

Reference: South Bend Lathe — Wikipedia.

Serial Number Identification

The serial number is the single most reliable identifier because Logan maintained a continuous serial ledger across its own-brand and private-label production. The stamped plate or boss is consistently located at the front-right corner of the bed, in the recess between the V-way and the flat way, near the headstock end.

To extract the serial number for lookup:

1. Clean the bed casting at the front-right corner with a stiff brass brush and light solvent. Do not use a wire wheel on the casting — it will erase the stamped digits.
2. Photograph the digits with a 10× loupe or macro lens and side-angled light. Stamps often fill with oil and grime that mimics the digit shape.
3. Verify the digit count. Logan serial numbers from this era are 4- to 5-digit numerals without letter prefixes.

Headstock Identification Features

Because Logan built both its own-brand and Wards-branded machines on the same headstock pattern, headstock casting geometry is the most discriminating visual identifier.

The presence of the front-right power-switch bore with the original Wards switch still fitted is a near-certain indicator of Wards Power-Kraft origin, even on a bed otherwise lacking branding.

Drive System Identification

Three drive configurations appear on machines from this production overlap period. Each identifies the builder and the customer's delivery route.

Logan Covered Drive

A Logan-patented enclosed belt guard that fully shrouds the spindle-to-countershaft belt run. The cover hinges open for belt changes. This drive is functionally reliable but is widely reported as difficult to service because the cover constrains belt tensioning. Logans shipped to government and industrial buyers in the early 1940s frequently omitted the covered drive in favor of the open-belt version.

Wards Open Drive

An exposed V-belt or flat-belt countershaft arrangement, mounted on the rear of the bed ways. Identical mechanically to the Logan open drive but supplied with Wards branding on the countershaft pulley and bracket.

South Bend Countershaft Drive

South Bend's countershaft is a separately mounted tunnel-shaft assembly with two-step and three-step pulleys, tensioned by a unique fork-and-rod mechanism. On a South bed the countershaft bracketry is cast with the South Bend part number series (e.g., PK-prefix for 9" workshop lathes).

Bed and Ways Configuration

Logan and South Bend both used a V-and-flat way pattern on their 9"-class workshop lathes, which is why the casting outline alone is insufficient for identification. Discriminating features include:

• Bed length: Logan 9" lathes were produced in 30", 36", 42", and 48" bed lengths. South Bend 9" workshop lathes (models A, B, C) share similar but not identical bed footprints.
• Serial boss location: On Logan-built machines, the serial number boss is on the front-right corner of the bed casting itself, cast integrally with the bed. On South Bend machines, the serial is stamped into a separate plate riveted to the bed.
• Footprint / cabinet stand: Wards Power-Kraft units shipped on a pressed-steel two-drawer cabinet stand with a chip pan. Logan-branded units shipped on either a similar cabinet stand or a fabricated steel legs-and-shelf stand depending on the buyer.

Change Gears and Accessories

The original change-gear set, when present, is a strong corroborating indicator. Logan lathes used a 16-tooth / 20-tooth / 24-tooth / 32-tooth / 40-tooth / 48-tooth / 56-tooth / 64-tooth set with a 16-DP (diametral pitch) and 14.5° pressure angle. South Bend 9" workshop lathes used a 20-, 24-, 32-, 40-, 48-, 56-, 64-, and 80-tooth set at the same DP but with a 20° pressure angle. The tooth profile angle is visible to the eye on the larger gears and is reliably measured with an optical comparator or a printed gear-tooth gauge.

A set of change gears in the original wood-hinged box with a Wards parts list sheet is a positive Wards Power-Kraft identification.

Cleaning and Field-Acquisition Procedure

Machines recovered from outdoor storage (leaves, exposure, light surface corrosion) are recoverable with the following field sequence:

1. Photograph the machine in its as-found state, including the serial boss, before any cleaning.
2. Disassemble the headstock, apron, and tailstock. Log the order of shim stacks and the orientation of any wave washers.
3. Soak castings in a 1:9 ratio of mineral spirits to kerosene for 24 hours to lift packed leaf debris and congealed way oil.
4. Scrape surface rust from ways with a hard-card scraper; do not use a wire wheel on the V-ways or flat way. A wire wheel will round the edges and destroy the geometry.
5. Lap the ways against a cast-iron reference plate with fine-grit compound only after confirming the geometry with a dial indicator. Bowed beds must be straightened or replaced before any scraping.
6. Inspect the spindle bearings (typically Timken tapered roller on Logan and South Bend 9" workshop machines) for brinelling. Replace the bearings before reusing the machine — brinelled bearings will replicate their damage into the spindle journals within hours of operation.
7. Reinstall with new way oil (ISO 32 hydraulic or way oil with EP additives) and re-verify spindle runout with a test bar. Acceptable runout is < 0.0005" at 4" from the spindle nose.

Documentation and Lookup Procedure

For definitive model identification, contact Logan Actuator Products (the successor entity that retained the Logan serial records) with the serial number, photographs of the headstock, drive, and serial boss. The current Logan contact is Scott Logan, who can confirm the exact model, year of manufacture, and original customer.

1. Email the Logan serial registry with the serial number and front/side photographs.
2. Cross-reference the response with the headstock switch-bore presence to confirm the Wards / Logan / government-direct configuration.
3. Document the lookup result (model, year, customer) and store it with the machine's permanent file. This documentation significantly affects collector value and parts-sourcing accuracy.

Troubleshooting Identification Matrix

Frequently Asked Questions