Pear Tree Engineering
Broken bolt/studs, taps and drills, repair stripped threads
With experience in the motor trade since 1962, we have come across numerous instances of
broken bolts, studs, drills and taps, together with stripped internal and external threads,
most of which we have successfully repaired with the use of appropriate equipment.
Many times these damaged components have been made worse by the use of wrong tools!
Damaged internal threads can often be repaired with a wire insert commonly called a Helicoil.
These are fitted by drilling out the hole to a special size and tapping to create a slightly
oversized thread with the same pitch as the original, an insert is fitted that is diamond
shaped in cross section, the outer flanks fitting into the newly tapped hole and the inner
flanks forming the same size as the original.
Sometimes a thick wall insert is used providing there is enough parent material.
The end result is a new thread that is the same diameter and pitch as the original, allowing previous
fixings to continue to be used as before.
Damaged external threads can be cleaned with an appropriate die or special cleaning tool.
Beware that this may not recover the full strength of the original thread.
A replacement fastener/component is generally the best option, where available.
Monday to Friday 9:00 am to 5:00pm
Saturday, 9:00am to 12:00 noon
Our mechanics are trained in the use of portable spark eroding equipment to
remove broken taps, drills and studs and in the fitting of wire inserts
commonly called Helicoils to reclaim stripped internal threads.