To extract a broken stud or screw, drill a hole in the screw, insert the largest possible screw extractor and turn anti-clockwise. The corkscrew teeth will release the broken screw, leaving the original thread in tne hole undamaged.
Drill Size 'A'-: For screw or studs of low or medium tensile strenght.
Drill Size 'B'-: For screw or studs of high (75 tons/sq. in .or over ) tensile strenght.
Screw
Drill to Use
Extractor
A
B
1/8 & 3/16'
5/64"
5/64"
1
1/4
7/64"
1/8"
2
5/16 & 3/8"
5/32"
11/64"
3
7/16'
7/32"
15/64"
4
1/2 & 9/16"
9/32"
5/16"
5
5/8 & 3/4"
13/32"
7/16"
6
N.B:- The nearest metric equivalent drill may be used for drilling holes if fractional size are not available.
