JUKI MO-644DN Instruction Manual page 9

Assembling thread stand
For overlock spools
For large spools
For spools of large inside diameter, position the anti-vibration come
upside down.
For small house-use spools
When using house-use spools, remove the anti-vibration cones.
Place a spool on the spoolholder with its notch downward and push
the spool caps on with the rounded outside edge at the bottom.
Notch
8