Recoil, Kato - General Design Practices
Drilling And Countersinking
Hand Inserting Tools
Tang Break-Off Tool
How To Install A HeliCoil
Screw Thread Insert
Drill - Drill out the damaged
threads using the drill size specified in the catalog.
Drill to sufficient depth to accommodate the insert
length and bolt or screw being used.
Tap - Use the Heil-Coil Tap specified
in the catalog. Check the size on your shank to make
sure you have the right one. Tap the hole to sufficient
depth to accommodate the insert length and bolt or screw
Install - Use the specified
installation tool. Just wind the insert into the hole
until the top coil is 1/4-1/2 turn into the tapped
Note: Remove tang with the appropriate tool
Drilling And Countersinking a
The suggested drill sizes for aluminum Iisted in the
catalog are within the minor diameter Iimits for
HELI-COIL tapped holes. Alternate drill sizes are
suggested in many instances for magnesium, steel and
plastics to provide for maximum tap wear life. In the
case of magnesium, the larger size is recommended to
allow for material close-in. The MINOR DIAMETER
should be within the limits shown.
Minimum drilling depth allows one pitch chip
clearance between the point of the plug tap and the
bottom of the drilled hole. Minimum drilling depths for
bottoming taps which have a shorter chamfer and no male
centers are given separately.
THESE DRILLING DEPTHS ARE MINIMUM AND SHOULD BE
INCREASED WHERE POSSIBLE PARTICULARLY FOR SPIRAL POINT
To prevent the feather edge at the start of the hole, a
120o +-5o countersink to diameter is recommended BEFORE
TAPPING. The minimum depth of the full tapped thread
takes into consideration 0.5 pitch for depth of
Drawing Callout - Example
Here is a typical drawing callout for HELI-COIL
Screw-Lock Insert M8xl.25 1.5 diameters long, for
Tolerances Class 5H. This can be abbreviated by using a
production process sheet to provide the operational
steps thus limiting the drawing to dimensional data
- 8.3mm Drill maintaining 8.271/8.483 Hole
Diameter to 23.5 minus 0 plus your standard drilling
- Countersink 120o ± 5o @ to 9.50/10.10 Diameter
- Tap with HELI-COIL STI
Tap No. 2087-8 (Tolerance Class 5H) to 13.3 Min.
Full Thread Depth
- Gage with HELI-COIL Gage
No. 1324-8 according to your sampling plan. P.D.
- InstalI HELI-COIL Screw-Lock Insert 4184-8CN12.0
with HELI-COIL Inserting Tool No. 7751-8.
- Break off driving tang with
HELI-COIL Tang Break-Off Tool No. 4238-8.
TooIs to remove HELI-COIL Inserts are Iisted below.
This is done by applying the tool to the insert,
striking the head of the tool a light blow and turning
it counterclockwise, maintaining steady downward
2.5 - 4.5mm, #3 - #8
5 - 10mm, #10 - 3/8"
11 - 24mm, 7/16" - 1"
27 - 39mm, 1-1/8" - 1-1/2" 1227-24
HeliCoil Hand Inserting Tools
Hand tools are designed with threaded mandrel and
patented driving contour to install HELI-COIL Inserts
correctly and efficiently. Complete instructions are
furnished with each tool.
HELI-COIL Strip Feed used with the Strip Feed Hand
Tool speeds up assembly, eliminates handling each insert
individually, eliminates waste and facilitates counting.
Strip Feed Hand Tools are available in sizes up thru
M7xl. To designate, add suffix -15 to Hand Inserting
Tool part number. Example: 7751-4-15.
The various designs of HELI-COIL hand inserting tools
are shown in the catalog corresponding to the active
insert. Generally, finer pitch inserts are
proportionately larger in the free state than the coarse
pitch inserts and thus have to be "pre-wound" to a
smaller diameter for installation. Large coarse pitch
inserts (and 2-56 and 3-48 inserts) need only a threaded
mandrel tool for installation.
HeliCoil Power Tools
HELI-COIL Power Tools are available in UNC & UNF
sizes #2 - 1/2" and up to 12mm, for rapid installation
of inserts. Power Tools consist of a front end assembly,
an adapter and a reversible air motor. All three
components are ordered separately. A Front End Assembly
consists of a prewinder, mandrel, and spacers.
Exhaust overhose, Part Number 8511-40, is available
and may be attached to the rear end of the air motor to
discharge air and mist.
HeliCoil Tang Break-Off Tools
The driving tangs of HELI-COIL Inserts should be
removed to eliminate their interference with the end of
the assembled bolt. Their removal provides greater
latitude in the depth location of the bolt.
Tang Break-Off Tools are available for use with inserts
up through 12mm / 1/2" nominal diameter. Their operation
is automatic, having a spring loaded, easily triggered
punch that strikes a sharp, uniform blow against the
tang of the installed insert. It can be operated with
For sizes >12mm / >1/2" use long nosed pliers. Bend tang
up and down to snap off at notch.
Tapping A HeliCoil
Types of taps:
- Plug Style
- Bottoming Style
- Spiral Pointed - Plug
- High Spiral Flute - Bottoming
- Roughing Tap
HELI-COIL Taps in various types and styles to produce
holes for Tolerance Classes 4H5H and 5H for use in the
general range of aluminums, magnesiums, mild steels.
These taps are designed and manufactured of high speed
steel to the most rigid specifications.
Conventional shop practice and production procedures,
speeds, feeds and lubricants should be used in
combination with proper fixturing and good tapping
machines or tapping heads.
The tapped hole must be held within the stated pitch
diameter limits for the required Tolerance Class of fit
for the installed HELI-COIL Insert.
When anodizing, Iridite or other finishes are used, all
tapped hole dimensions must be met after finishes are
Working Gages - Working gages
provide a guaranteed minimum wear allowance on the pitch
diameter of the GO members of .0002".
Reference Gages - Reference gages
have pitch diameters on or close to minimum. They are
essentially laboratory or master gages and should be
used in case of conflict between 2 working gages, which
can arise due to one of them having more use and wear.
Complete Gages - The Complete Gage
consists of the GO thread plug gage, the HI thread plug
gage and the appropriately marked gage handle.
TANGLESS® is a registered
trademark of Advanex Inc.
POP Rivet® is a registered
trademark of Emhart Teknologies, LLC.
Recoil® is a registered
trademark of Alcoa.