Damaged HeliCoil Repair Procedure
(A320, A740, A760, A770 and A790)
This article describes the operational background and procedure for the replacement of damaged HeliCoils ( http://www.stanleyengineeredfastening.com/brands/heli-coil ) on the main chassis of Getac (www.getac.com ) A-Series rugged laptop computers. Although this article uses an example of the Getac A790 rugged laptop, the same procedure is applicable for the entire A-Series comprised of the Getac A320, A740, A760, A770 and A790.
The A-Series of Getac rugged laptop computers use hinged metal doors with sealing gaskets to protect the internal circuits and devices from rain and dust. Each door or hatch has two to three captive screws used to tighten the seal when the door or hatch is secured in the closed position. (See example photo below). The threaded holes in the chassis are reinforced with HeliCoil inserts so the holes in the aluminum chassis are not damaged by everyday use.
In actual operational use, sometimes the Getac A320, A740, A760, A770 and A790 captive screw can be cross threaded and damage the HeliCoil insert and that is why this procedure was developed.
The parts required for the Getac A-Series (A320, A740, A760, A770 and A790) kit include an extraction tool for the old/damaged HeliCoil and a set of tools and inserts to install new Time-Sert HeliCoil replacements. The Time-Sert replacements are recommended as they are self-locking and have a shoulder flange. The next three pages documents the kit and tools followed by the replacement procedure. The tolls are available from Amazon or other tool suppliers.
HeliCoil Extraction tool: 1227-06
Occasionally HeliCoil inserts must be removed. Inserts may be removed manually with a little effort. This is done by inserting the blade of the extracting tool into the HeliCoil insert so that the V section of the blade is toward the top end of the insert. Strike the head of the tool with a light blow. Maintaining a steady pressure of blade against insert, turn the extracting tool counterclockwise until the insert is removed.
TIME-SERT M3 X .50 Metric Thread Repair Kit 1305 $74.31
TIME-SERT is a sophisticated thread repair system that is considered by many to be superior to any other method of repairing stripped or damaged threads. TIME-SERTis a solid bushing insert. This facilitates easy installation and allows for full torque to be applied to repaired threads, ensuring a strong, permanent repair. TIME-SERT is thin walled due to synchronized internal / external threads. Small outer diameter allows for installation in areas where clearance is critical. TIME-SERT is self-positioning. The flange on the top of the insert will insure that the insert cannot wind down into the newly repaired hole. TIME-SERT is self locking. On installation the bottom internal threads of the insert expand to lock the insert in place.
# 0 to 1/4″ Tap Handle
Place removal tool into HeliCoil in Getac laptop chassis and give a light tap with a hammer to seat it in the coil.
Unscrew the HeliCoil counterclockwise until HeliCoil is removed from the Getac laptop chassis
Next, counter bore the hole in the Getac laptop chassis using the tool supplied. It will stop when the proper depth is reached:
Clean away the chips and prepare the insert for installation into the Getac laptop chassis. Be sure to put a drop of oil on the insertion tool before the insert goes on.
Thread the insert into the hole and begin installing it, clockwise. After a number of turns, it will tighten up, continue turning, as the insert is being locked into the threads. Once installed, the effort to turn will reduce, at which point you can back the tool out, counterclockwise.
This is how the installed insert will look once installed in the Getac laptop chassis:
Access door center screw holes: do not have HeliCoils, if the threads are damaged, they must be drilled and tapped to accept the insert. This is a picture of a good one.
Using the supplied drill bit, drill out the threads. This hole cannot be counter bored due to the shoulder at this location, proceed with the tapping of the hole.
Be sure to use a drop of oil on the tap and stop when it bottoms out, taps are brittle and will break if stressed. Clean away tapping chips. Install the insert on the tool, with a drop of oil:
Then start threading the insert into the tapped hole, clockwise. Continue until the tool turns a bit hard, then until it bottoms out.
Remove the insertion tool by turning it counterclockwise. This is the complete center hole repaired with insert:
Depending on which hole needs repair, you might need to get shorter inserts as they could protrude on the inside of the unit due to the counter bore. This might happen to the door screws as well. The protrusion is OK as long as there are no components on the inside to touch.
HELICOIL SCREW THREAD INSERTS
About HeliCoil Inserts
HeliCoil inserts are helically wound, precision formed coils of extremely hard stainless steel (18-8) diamond shaped wire. When installed into a HeliCoil tapped hole, the HeliCoil insert provides permanent conventional screw threads. It has a driving “tang” for installation, which is notched for easy removal.
Stripped & Fixed
When threads become stripped, worn or damaged for any reason, the strength and reliability of the bolt is greatly reduced. Potentially dangerous situations are eliminated when the damaged threads are repaired with HeliCoil inserts. They quickly and permanently restore stripped, worn or damaged threads to their original size and condition.
HeliCoil inserts provide stronger, more reliable threads than the original tapped hole and at the same time, eliminate the possibility of thread wear, corrosion, galling, seizing and rust.
HeliCoil wire thread inserts are larger in diameter before installation than the tapped hole. During installation, the HeliCoil inserting tool reduces the diameter of the leading coil so that the insert can enter the tapped hole. After successful installation, each high tensile stainless steel coil of the HeliCoil insert expands outward against the tapped hole to permanently anchor it in the hole.
Quality & Reliability
Since its inception in 1938, Emhart Technologies HeliCoil screw thread inserts have become synonymous with thread repair and they have also been recognized for their superior quality and reliability. They have an extensive background of tension, torque, shear, vibration and fatigue tests conducted by the American industry’s leading companies as well as the U.S. Military.
Successful applications in the fields of aviation, electronics, industrial, automotive and military equipment provide a wealth of experience and confidence in the performance and reliability of HeliCoil inserts.
TIME-SERT® PROFESSIONAL THREAD REPAIR SYSTEM SCREW THREAD INSERTS AMERICAN & METRIC SIZES
TIME-SERT® ( http://www.timesert.com ) is a solid bushing insert. This guarantees easy installation and allows for full load use of tapped hole, ensuring protection against stress and vibration.
TIME-SERT® is thin walled due to synchronized internal external threads. Thin cross sectional area allows for installation in areas of limited space and clearance material.
TIME-SERT® Positive Placement. Having a flange on the top of the insert will insure that the insert will have positive placement and cannot wind down into the newly repaired hole.
TIME-SERT® is self-locking. On installation the bottom internal threads of the insert are cold rolled to expand the mating external threads into the base material locking the insert in place. Locking mechanism is at the bottom of insert.
TIME-SERT® thread repair system the ultimate way to repair threads in stripped or damaged holes.
TIME-SERT® threaded inserts are approved by leading automotive manufactures. Easily repair stripped threads in cylinder head bolt stripped threads, spark plug thread repair as well as oil drain pan. Many thread repair kits are available for your threaded bushing application in metric and American sizes. TIME-SERT the very best in thread repair!