Plastic bobbin modification for old Singer machine winding - difficult - enlarging bobbin hole

Be sure to smoothen the edge of the hole on both sides. Update: a canadian brand sells type 66 bobbins with the correct center hole, see this other video https://rumble.com/v6ef0ag-singer-plastic-bobbin-that-fits-winding-canadian-brand-vintage-old-sewing-m.html
New plastic 66 bobbins may not fit on the winder shaft on vintage Singer sewing machines - here's how to fix this. For 301 301A 401A 403A 404A 500A 503A 600E