THREADED INSERTS

Threaded inserts have a very wide application and are typically used when wood assemblies are required to be able to be "knocked down" or dis-assembled.  Threaded inserts allow the repeated use of any compatible machine screw or bolt with no wear or damage to the components.

We offer inserts in either SOLID BRASS or ZINC ALLOY. The brass are all UN-FLANGED and may be inserted level or below the surface. The zinc options are either UN-FLANGED or FLANGED. The flanged versions require a countersunk insertion hole for a flush finish.  

INTERNAL THREAD

Thread options internally are applicable world wide and either METRIC measured in millimetres with a 60 degree thread angle or imperial inch sizes in UNC/WHITWORTH with a 55 degree thread angle.  They are incompatible with each other.

(UNC = Unified Coarse is a standard used in America and confusingly uses gauge numbers for sizes under 1/4 inch.  What we in Australia may know as a 3/16th inch may be referred to as a 10--24 in US publications - a 10 gauge screw with 24 teeth to the inch. UNC and Whitworth are approximately compatible in sizes up but excluding 1/2 inch ).

EXTERNAL 'THREAD'

The external threads on these inserts do not follow any standard that I am aware of and as far as I know threading taps are unavailable.

THREAD PITCH

Thread pitch is a measure of the distance between adjacent teeth. Metric pitches are simply measured in millimetres,  UNC/Whitworth pitch is a count of the number of threads to an inch of the screw.

Standard Metric Coarse (there is a Metric Fine - rarely encountered) are as follows:

• M3 x 0.5mm
• M4 x 0.7mm
• M5 x 0.8mm
• M6 x 1.0mm
• M8 x 1.25mm
• M10 x 1.5mm
• M12 x 1.75mm

INSERTION

All inserts are best seated using a mandrell as offered below.  The zinc versions can be seated using a up-scale allen key. This may be problematic in harder woods.   The brass inserts may have a slot for an insertion tool which we don't offer. We do not suggest the use of a screwdriver which may chew up brass inserts.

The root diameter is the diameter of the insert at the bottom of the external teeth and is the minimum diameter of the drilled hole required.

The insertion hole is often varied slightly to accommodate harder woods

Inserts can be inserted at an angle.  A pre-drilled, angled, landing flat assists with this, drilled with either a forstner or spade bit.

Given a long enough insertion mandrell it is possible to gang 2 inserts together for greater strength.  It may be wise to have a machine tap to finish the job. You can seat the inserts with a little adhesive taking care not to get glue on the internal threads.

Note: We can only source long set screws with a hex head drive so for double or triple gang insertions be sure to order a hex head drive mandrell and not a hex key drive which we can only source in shorter lengths.

NOTE: Due to disruptions in supply we occasionally have to substitute inserts versions from different suppliers

If you are not equipped to cope with variations please email prior to ordering so that we can confirm the version in stock.

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Mandrell insertion Options

See HERE

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