9/16"-5/8" French Fell Fabric Seam Folder for Industrial Double Needle Sewing Machines (#09 & #09A)

This is a French Fell Seam Folder that produces a nominal 9/16" - 5/8" wide finished seam (depending on print tolerances, fabric type, and sewing techniques) and is suitable for any double-needle industrial sewing machine of approximately 3/8" needle width or less.

It is designed to optionally enclose a single layer of 1/2" wide, 2500-pound, Kevlar load tape (typical of commercial products such as Herculine or Mule Tape) inside the seam. The fabric encapsulates the Kevlar webbing inside the finished seam to protect it from UV degradation. This is a well-proven method of hot air balloon construction. The normal french fell seam type that this folder creates is also used for sewing parachutes.

Not all double needle sewing machines have the same throat plate dimensions, so I've made available two variations of this folder to fit the two most common double-needle machine throat plate sizes I've encountered. The #09A 76x56.2mm folder will fit the Singer 112 / 212 series and most clones and similar machines. The #09 76x50.2mm folder was designed to fit a Juki LH-1152 and other machines with that throat plate size.

PLA works just fine. You will definitely need to tweak your own 3D printer's settings to get your best print quality. 100% infill is recommended. Printing with the folder in a vertical orientation (nose down) is really the only way to do it. I use build supports and a brim (or a raft). Make the nose of the throat plate have a fairly tight tolerance to the brim/raft, because the smaller the gap, the more the plate will adhere to the raft. This makes for less printing errors in the first few layers of the curved front "nose" of the throat plate that have minimal supports.

After printing and removing supports, the side rails of the throat plate where it slides into your machine will likely require sanding carefully with a square-faced file to fit your machine. Don't file away too much! You want the plate to have a slightly tight fit so that the rear of the folder doesn't have a chance to move at all left or right (and off-center the seam).

More folder sizes and configurations will be forthcoming as I redesign this is

This folder and other information about its use can be found at: https://www.apexballoons.com/tips/