Reverse-engineering a ribber dial for a 100-year-old circular sewing machine
A working ribber dial for a 100-year-old circular sock-knitting machine. No drawings, no spares — just measurements taken from the original parts and SLA prints at the tolerances the mechanism actually needed.
What they came to us with
David came to us with a 100-year-old vintage circular sewing machine that needed a new ribber dial — the part that holds horizontal latch needles for ribbing. Circular sewing machines knit socks and other tubular garments: vertical needles in the cylinder, horizontal needles on the dial pulling the rib pattern through.
The challenge was that no mechanical documentation existed for the part. Dimensions had to be measured from the original components and fine-tuned by hand — no drawings, no spares, no margin for sloppy tolerance. The dial has to mesh with a hundred-year-old mechanism that won't accommodate a half-millimetre error in any direction.
What we did
SLA grey resin was the right call here over FDM. Sock-knitting machinery sits in the territory where home FDM printing tends to fall short: layer steps, marginal tolerance accuracy, and post-processing required to get a working surface. SLA gave David the surface finish and sub-millimetre accuracy he needed without the cleanup overhead.
The reverse-engineering process worked from David's own measurements of the original parts. We printed in SLA grey, checked, and refined where tolerance needed adjusting before the final part came off the printer.
“The printed parts came back and worked well. The SLA sizing being more accurate than home 3D printed parts that have not been sufficiently accurate.”
— David Johnston — personal restoration project
Result
The printed parts came back, fitted the original mechanism, and the dial works. A 100-year-old machine that hadn't moved in years is operational again.
A clean illustration of why SLA resin remains the right choice for tight-tolerance reverse-engineering work over FDM — especially on heritage mechanical parts where you only get one chance to fit.
Got a project like this?
Upload your STL, STEP or mesh file. Get an instant price and same-week turnaround on most parts.