If you can thread the over-sized hole, a threaded insert would need just a dash of loctite-anything to secure it.

I’m with NDIY

On 16 February 2026 at 13:13 not done it yet Said:

If you can thread the over-sized hole, a threaded insert…

In the situation described, the insert is 6mm dia., so presumably M6 thread and 5mm tapping drill. The other component has an M4 thread. That leaves a 0.5mm wall thickness.

Using M6 x 0.5 thread on the insert improves the situation. Using loctite and no thread at all improves it further.

Wire thread inserts are another repair possibility if the worn hole is not too bad. A good indication is that there remains a slight witness of the original thread. Of course you need to buy or borrow the kit. The resultant threads are accurate, strong, and very durable if made of hard drawn stainless wire. Another benefit is that this needs the the least diameter increase for the repair.

Phil – that’s what Malcolm suggests, “Helicoil” being simply a brand.

Be careful though if the finished work has to withstand corrosive conditions such as damp ground or salty water. Stainless steel in intimate contact with aluminium can result in the aluminum disappearing while the insert stays pristine.

Even mild-steel can have similar effects.

(I’ve sometimes wondered this in the case of miniature ground-level railways using aluminium rail and steel, especially stainless-steel, fishplate bolts.)