Enhanced strength screw-type masonry anchor

A screw-type self-tapping masonry anchor for fastening an attachment to masonry having a hole of predetermined diameter drilled therein;

• said anchor comprising:
• A. a shank having a root whose diameter is smaller than that of the hole;
• and
• B. a plurality of helical male cutting threads surrounding the root having like helix angles and crest diameters larger than the drilled hole, said cutting threads forming convolutions which are substantially equi-spaced along the root to produce multiple convolutions along the root whereby when the anchor is turned into the masonry hole it advances at a rate determined by the pitch of the threads to cut a corresponding number of female threads in the bank of the hole, thereby enhancing the resistance of the anchor to pull-out forces.

A screw-type masonry anchor which is screwable into a hole of predetermined diameter drilled in masonry, said anchor comprising:

• A. a shank having a root whose diameter is smaller than the diameter of the hole;
• and
• B. at least two helical male cutting threads having like helix angles surrounding the root and having respective crest diameters exceeding the diameter of the hole to cut corresponding female threads in the bank of the hole;
• said two threads having leads which are angularly displaced to form multiple equi-spaced convolutions along the root to define a helical land therebetween into which is discharged particulate debris produced by the cutting action on the masonry.