Helicoils

[Morrisman]

How about drilling a fair bit deeper and using longer studs? Or against the rules?

 

[indykid]

How about drilling a fair bit deeper and using longer studs? Or against the rules?

I haven't managed to find a section view of tony kart hubs but it looks like that space is occupied by the axle. I presume there is only quite limited material thickness on the end face to go at so not a lot of thread engagement. Certainly doesn't look like the 2xD you'd want

 

[Morrisman]

I haven't managed to find a section view of tony kart hubs but it looks like that space is occupied by the axle. I presume there is only quite limited material thickness on the end face to go at so not a lot of thread engagement. Certainly doesn't look like the 2xD you'd want

I’d get hold of a scrap one and see how far you can drill before it breaks through to somewhere.

 

[Misterg]

The part is pretty similar to the below.

Just helicoil it and be done with it

Lots of military stuff with aluminium casings gets helicoils fitted to all the threads as standard as they are stronger and longer lasting than threads directly into alloy.

 

[Seadog]

Correct. The avionics kit that I recall from Plessey in the 70s all had helicoils fitted in production. They weren't doing it because it looked pretty.

 

[bricol]

I don't think Bolloff claim they are stronger - I don't go for it either - other than the insert has to be a slightly bigger size than the original tapped hole, so gains a hint of extra strong-ness there.

They are certainly harder wearing for fasteners being removed, re-inserted etc repeatedly though - change parts in a machine for example.

For parts that are simply assembled, they are a waste of time in decent material - we tested high tensile screws into a decent grade of aluminium, torqued to spec and then torqued until something failed - and it wasn't the thread in the aluminium, every time up to M12, the screw snapped first.

As for thread engagement - depends on the material - simple calcs will determine the thread depth needed to avoid failure when torqued up - threads into decent steel with high tensile screws probably will work out at 1.5D - but into weaker materials, you might need considerably more.