Lots of brake cleaner, and an old (well cleaned) mascara brush liberated from a friendly female (or male who uses mascara!).Although the bigger question is why the thread needs to be 25mm long @m3. That’s 50 threads in engagement. Rule of thumb seems to be 1.5 x bolt diameter i.e 4.5mm or 9 threads seems to be optimum.

Or perhaps a cotton bud screwed in

Pipe cleaner with the grease and oil remover(Painters prepsol) then rinse with the loctite cleaner. Loctite 648 works well to glue ali threads and if going to 250c then use 620 high temp. But 620 is very slow curing. JB is very fast curing by comparison. You can thin JBweld by heating it and the parts to 40-50 c before assembly. It will cure in about 3 hrs at 50c

If it is open both ends remove the thread from  lot of it to the as measured clearance for the threaded rod. You don’t need ten times the diameter of the thread all locked.

If squirting anything down the hole, including air, wear proper eye protection.

About 28 years ago I was doing this task on a large aluminium alloy cylinder. I grabbed a pressurised can of “Solvent Cleaner” that had been donated to the project. It seemed to work but several seconds later there was smoke coming out of the M4 tapped hole! The solvent was carbon tetrachloride and started a exothermic reaction with the finely divided and unoxidised (due to tapping oil) alloy particles. It had been donated because the ban on it’s sale and use was looming and a donation saved the supplier paying for disposal….

Robert.

On 14 May 2025 at 16:00 SillyOldDuffer Said:

On 14 May 2025 at 12:51 Robert Atkinson 2 Said:

If squirting anything down the hole, including air, wear proper eye protection.

…

Robert.

In some firms it’s a sacking offence to clean out with compressed air.

When I said “a quick blow” I meant my own lung power 😅