My question is with regard to retapping from the Raleigh 26 to 24. Are the tools sold to retap bottom bracket thread designed to retap or just to rethread? The reason I ask is that whne you take a cup out of a Raleigh, the existing thread is 50% of the thread required for a Cartridge cup. That means that once the existing 26 has been tapped to 24, the tool then has to cut thread into fresh pipe to get the needed width.
Are the bike tapping tools suitable for this. Does it have a destructive effect on the retapped thread the tap has to pass over. All the vids I've seen show the tapper spinning the tool like a crank - not heaving with it as it carves out fresh steel?
Anyone done it and left a nice bit of even and undamaged thread?