BackgroundThe story
The 401A was Singer’s answer to the flood of foreign zigzag machines after the Second World War (silverbobbin). It was the company’s second slant-needle design after the 301, and the “A” tells you it was built in Anderson, South Carolina. Dates vary by source: pungolivinghome gives 1958–60, the ISMACS model list gives 1957 onward, and silverbobbin says 1956–61.
What made it special was the cam stack inside. You get a set of built-in patterns from a selector, and you can drop in plastic “Special Discs” for more. Oldsewingear counts seven built-in primary patterns; pungolivinghome says 18 built-in stitches, probably counting combinations. Twin-needle sewing, three needle positions and an aluminium body with steel gears made it a favourite for heavy work like canvas and denim.
In Europe the design carried on as the German-built 401G (1960–64 per ISMACS), and in the US its mechanism lived on in the 500A Rocketeer. Today it is one of the most sought-after slant-needle Singers.
ReferenceSpecification
Specification plate
- Years made
- 1958–1960 per pungolivinghome; the ISMACS model list gives 1957 onward for the 401A.
- Factory
- Anderson, South Carolina (pungolivinghome).
- Build
- Full-size portable or cabinet machine, slant shank. The 400 series has a 16.5 × 7 inch bed and is tan and cream.
- Hook and bobbin
- Horizontal rotary hook, Class 66 bobbin.
- Needle
- 15x1.
- Drive
- Internal motor, gear drive.
- Stitches
- Zigzag with built-in stitches chosen by a selector, plus top-hat cams (“Fashion Discs”). Three needle positions; twin-needle capable.
- Feed
- The feed doesn’t drop; a three-position lever raises the needle plate instead.
IdentificationHow to recognise a 401A Slant-O-Matic
Lift the hinged top cover and you should see a chart of the built-in stitches. A 403A has no built-in stitches, so this is the quickest way to tell them apart.
The 401A has selectors for its built-in patterns. Oldsewingear notes the left-hand selector must be set on “A” for primary patterns and twin-needle work.
Look for a double thread tensioner and two spool pins. They let you sew decorative stitches with two needles at once.
Instead of dropping the feed, a lever lifts the needle plate: flat for sewing, slightly raised for darning, fully raised for removal.
The handwheel has a clutch knob so you can wind a bobbin without the needle moving. The bobbin winder flips up and stops automatically when full.
ISMACS describes the 400 series as tan with a cream top and handwheel. The German 401G is listed as beige.
VersionsVersions and sub-models
| Version | What sets it apart |
|---|---|
| 401A | US-built at Anderson, South Carolina, with built-in stitches plus Special Discs. |
| 401G | Made at Karlsruhe, West Germany (1960–64 per ISMACS), with a top-mounted bobbin winder, a thread control, a lighter casting and treadle capability. |
| 411G | German version similar to the 401G that can also chainstitch, using a special bobbin case (ISMACS; archaicarcane). |
| 421G | German zigzag listed by ISMACS with the same built-in stitches as the 401. |
| 431G | Free-arm (tubular-bed) version of the 411G, 1964–65 per ISMACS. |
Parts and accessoriesBobbins, attachments and the parts it takes
Drop-in Class 66 bobbins sit in the horizontal rotary hook. Oldsewingear lists four bobbins in the original accessory box.
The manual calls for 15x1 needles in sizes 9 to 18. The clamp holds one or two needles, flat side to the back.
Five discs (Nos. 1–5) came in the box. Singer made 24 in all for the Slant-o-Matic and 600 Touch & Sew families; some 600-series discs have a thicker centre ring and need slight modification to fit a 401 (oldsewingear).
The original box held needle plates, zigzag, straight-stitch, button and special-purpose feet, an edge guide, hemmer, zipper foot, binder, ruffler, oil bottle, screwdrivers and a lint brush (oldsewingear).
Only slant-shank feet fit. Some 700-series feet work, but 700-series Flexi-Stitch discs and needle plates do not (oldsewingear).
Portables came in a case with a slot for the attachment box. A blonde cabinet was also offered (Oil and Thread).
MaintenanceLooking after it
The manual says to oil after each cleaning: a drop at each marked point, the hook raceway under the slide plate, and underneath via the cover held by a screw (keep its felt washer).
Remove the arm top cover to lubricate the gears. Restorers follow the rule “grease for gears, oil for everything else” (archaicarcane).
The manual states the motor needs no lubrication. Archaicarcane does add oil where the worm gear enters the motor housing.
Drip a solvent-bearing oil such as Tri-Flow down the selector pillars and work the parts back and forth without forcing. Avoid WD-40: it turns sticky and can damage decals (archaicarcane).
Running the machine steadily works fresh oil into gummed pivots faster than leaving it to soak (archaicarcane).
General advice from the sources listed below. If in doubt, follow your machine’s Singer manual.
Before you buyWhat to check on a used 401A Slant-O-Matic
A common fault on the 401A, 403A and 500A is a cam stack or stitch selector that won’t move because old oil has hardened. Restorers check the piston under the cam stack, the follower pivots, the pillars and collars, and the needle-bar joint (archaicarcane.com).
In-person checks
QuestionsFrequently asked questions
What is the difference between the Singer 401A and 401G?
The 401A was made in Anderson, South Carolina; the 401G in Karlsruhe, Germany. The 401G has a top-mounted bobbin winder, a thread control, a lighter casting and can be treadled.
Do 500A or 600-series cams fit the 401A?
Yes, Special Discs for the 403, 411, 431, 500, 503, 600, 603 and 626 fit. Some 600-series discs have a thicker centre ring and need slight modification (oldsewingear).
Can the Singer 401A sew denim and canvas?
It has a reputation for heavy work like canvas, denim and quilt layers, thanks to its gear drive and steel gears (silverbobbin). Use a suitable needle size.
How do I free-motion or darn on a 401A?
The feed doesn’t drop. Move the throat-plate lever to the middle position to raise the plate above the feed dogs.
What oil and grease does a 401A need?
Sewing-machine oil on the marked points and gear lubricant on the gears, per the manual. The motor needs no lubrication.
ReferencesSources
Where sources disagree we show each figure rather than choosing one. Spotted an error? Tell us.
- ismacs.net/singer_sewing_machine_company/singer-model-400-series-descriptions.html
- pungolivinghome.com/home-2/our-collection-2/the-singers/model-401a-slant-o-matic
- archaicarcane.com/stuck-in-the-middle-frozen-slant-o-matics
- ismacs.net/singer_sewing_machine_company/singer-class-401-sewing-machine.html
- ismacs.net/singer_sewing_machine_company/model-list/classes-400-499.html
- www.oldsewingear.com/401--403--404.html
- www.oldsewingear.com/blog/do-i-need-special-discs-for-my-401
- silverbobbin.com/singer-401a-sewing-machine-history-value-review
- www.manualslib.com/manual/586892/Singer-Slant-O-Matic-401a.html
- oilandthread.blogspot.com/2013/04/meet-singer-401g.html
Last reviewed October 2026