Enlan is using a triangle screw for the pivot joint e.g. on the Enlan EL-01 knife. To adjust the knife's folding mechanism you need to buy a special tool. Do not buy it - just print it. :) Depending on your print material you may need to scale the object a little bit to match the screw. Try a setting of 99% or 101% if your first print does not fit on the screw.UPDATE:I just uploaded a version for older knives that have a screw with a silghtly larger tri-wing shaped head.