Chamfered bb, possibly, questions

[fiveSixteenths]

Have managed to remove (without caustic, amazingly) a BB named ‘YST Corp’ which appears to have the same chamfered inner faces to the locknuts
The inside faces of the frame’s bb also appear gently chamfered as well
Does anyone know if a Mavic bb replacement would work, or, given the threads look quite worn (as the whole thing seemed to have been bodge-secured with a huge washer thing), should / could a threadless replacement be best?

The biek is a lovely karma Roberts 531ST (which is a bit too big for me I suspect but a taller son has eyed with interest so well worth the effort, from @LondonClassic

 

[LondonClassic]

Really pleased you got a result here @fiveSixteenths - lot of work but you have a functioning Roberts ( or two ).

 

[Jonny69]

This was probably put in because the original bb threads were knackered. You usually chamfer the inside faces to make it locate properly in the bb shell.

 

[MartinB123]

I *think* I have one of those mavic BBs, Rich!

 

[fiveSixteenths]

This was probably put in because the original bb threads were knackered. You usually chamfer the inside faces to make it locate properly in the bb shell.

Wondered as much. The threads currently look like I cut them with a fingernail…

 

[fiveSixteenths]

I *think* I have one of those mavic BBs, Rich!

Ah, will pm