S ec t i o n 1 -P a g e8 May 2013 Oversize Holes - Holes 1 / 8 " oversized can r educe holding str ength by 70 Oversized holes can be caused using the wr ong bit size, leaving the drill running while ushing the hole, soft gr ound (faults, gouge, etc.) and bent drill steel. Undersized Holes - Undersized holes will not permit the plug in the expansion shell to seat pr operly . The leaves or bail can br eak and distort upon for ced entry . Undersized holes ar e usually caused by wor n bits and/or wr ong bit sizes being used. Friction Flair Expansion Shells - A r ecent impr ovement in expansion shell design is the addition of airs or wings on the bail strap at the bottom of the leaves. Installation is impr oved as ther e is no need to set the anchor to keep the bolt fr om sliding out of the hole during installation. Theanchor sets up faster as the plug engages the leaves fr eely . Spinning of the anchor in the hole is pr evented, ther eby eliminating the principal cause of bolt failur e upon installation. Resin Anchors - Using a r esin cartridge to assist in anchoring mechanical r ock bolts is gaining popularity . If used with an expansion shell, the shell must have pr ovisions for the passage of r esin ar ound the shell wedge. This ensur es pr oper encapsulation of the expansion shell without causing any damage to the assembly . Expansion Shell Plastic Sleeve - The plastic sleeve holding the leaves together on an expansion shell should be r emoved prior to installation. If left on it could r esult in poor anchorage. Set Up of Expansion Shell - Immediately prior to installation the expansion shell should be set to the corr ect diameter to enable the bolt to be pushed up the hole by hand, set and anchor ed. If not expanded enough ther e will be dif fculties in anchoring. If expanded too much the end of the bolt can br eak the bail or leaf attachment prior to the leaves being set. continued Installation Quality Guidelines continued www .dsiundergr ound.com