Re: OT: stripped aluminum nut

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Posted by Ben ( on 14:33:12 06/06/08

In Reply to: OT: stripped aluminum nut posted by Peter

Is the screw in line (longitudinal) with the extrusion, or square to the extruded 'groove'?

Is the clearance hole of the piece being held on 'okay' to increase in dia?

Is the fastener in shear or tension?

How deep is the threaded portion?

What type of thread was on the fastener and groove?

What type of screw head?

Does the finished appearance matter?

If in line (longitudinal) with the groove and can increase the clearance hole dia, consider finding a
new screw with 'type AB' or 'type A' threads/point. Go as long as you can, but note
that too long and the torque necessary can/will snap off the head.

If square to the groove, then a tougher nut to crack.

If so, can you drill it deeper and then use a larger dia and longer 'Type AB' fastener?

Type AB is best for extruded aluminum as long as the 'virgin' hole is sized correctly to the
fastener root dia.

This type of thread is a self tapping, but does not 'cut' material away, but flows (extrudes)
material to form complimentry threads in the 'hole'/'groove' with *NO* space, but full contact
throughout the thread engagement.

Type AB fasteners come in a variety of head types and'll usually have to buy a
bunch or in small quantities...expensive. Everyone should have a good and varied supply of fasteners
and I never have enough... :)

If this is a 'fine' thread, then maybe not able to use a Type AB fastener, but I've been able to do
that on most, even thin sections. Issue with fine threads is that the material usually is thin and
Type AB will not have enough material to deform and extrude to make up new threads. Okay if you
drill an undersized hole and then the 'extra' material will come from the fastener plowing into
a too small hole.

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