Pretty confusing, right? So which disc is which and which machine do they work in? Let's take a closer look.
Note: I've only listed model numbers that are known to work with the disc shown. Discs may also work in other models but have not been tested.
Singer Fashion Disc
Fashion Disc Small, flat disc fits vertical needle machines such as 306 and 328.
Singer Special Disc (Type 1)
Fashion Disc / Special Disc (Type 1) Top-hat style disc with slim center ring with 2 adjacent holes. Fits 401, 403, 411, 431, 500, 503, 600, 603, 626, 648
Singer Special Disc (Type 2)
Fashion Disc / Special Disc (Type 2) Later top-hat style single-layer disc with wide center ring surrounded by 4 holes. Fits 690, 700, 758.
Singer Flexi-Stitch Disc
Flexi-Stitch Disc Double-layer disc with top-hat center ring surrounded by 4 holes. Fits 690, 700, 758. (Often packaged with single-layer type-2 special disc.)
Singer Flexi-Stitch Disc
Flexi-Stitch Disc Double-layer disc with top-hat style center ring with one adjacent hole. Fits 740/760. (May be packaged with single-layer type 1 special disc.)
Singer Futura Disc
Flat reversible disc has a pattern on each side. Fits Futura models.
So we can see at a glance that the small flat disc and the larger white discs WON'T work in a 401 or 500 machine.
(The white discs are double-layer discs designed to work in machines with two cam-followers. This allows patterns which move the fabric forwards and backwards to produce complex designs such as Greek Key, Flowers, or Ducks. While Elna and Necchi were producing double- and triple-layer discs as early as the 1950's, Singer didn't catch up until they introduced the 700-series Touch & Sew models in the late 1960's.)
So the white discs are out, but you may still be confused by the two styles of black top-hat discs (I personally call them Type 1 and Type 2, but it's not an official name). So let's compare them side by side:
Except for the thicker center ring and number of holes, they look pretty identical, don't they?
Which means either one should work, right?
Wrong. A closer examination reveals that the later disc is also slightly shorter.
This difference in height combined with the fatter center ring means that this disc doesn't snap firmly into place on the 401/403, 500/503, and 600/603 models.
The issue can be clearly seen when comparing both discs side by side in the machine:
As you can see, the overhanging lip on the later disc hangs up on the post, preventing the disc from seating firmly. The disc sits crooked and eventually wobbles loose, resulting in an erratic stitch.
The simple solution is to make sure you purchase the correct disc in the first place. But what if you can't find the correct disc?
There is a creative solution. A dremel tool with a sanding tip can be used to grind down the overhanging lip which will allow the disc to snap into place. Be careful to remove as little plastic as possible so as not to compromise the structural integrity of the disc.
So there you have it. Now you know what to look for to select the right disc for your 401 or 500 Slant-o-Matic. And if you accidentally wind up with the wrong disc, there's still a way to make it work!
That's what I call a win-win.
Happy Sewing! Barbara
OldSewinGear...dedicated to helping you get the most out of your old sewing gear.
OldSewinGear is the collaborative effort of retired repairman Gary and daughter Barbara. We love old sewing gear and enjoy sharing what we've learned in our vintage sewing machine adventures. We are located in Roseburg, Oregon.