Since the screws won't adhere out within the surface, they won't capture on to things that could omit the fabric. This is the circumstance once the flanks with the threads come into intimate contact with one another, ahead of the roots and crests do, if whatsoever. Square Head- Square heads https://typesofcaliforniaroof82592.wizzardsblog.com/29394129/a-review-of-lead-screw-thread-type