Thread restorer (internal)

[doobin]

I’ve got bolts and taps for that, in Sussex if that helps. 

[openspaceman]

1 hour ago, aspenarb said:

The best tools for repairing internal threads are the ones that start at the bottom of thread, you then expand them and turn them out. Trouble with starting at the top with a conventional tap is the danger of overcutting.

 

 

Brilliant, I've not seen one of those before

[spudulike]

Looks like the offer in the post above your last one may be a nice one, sort of thing that this site is often good at.....sometimes! 

[Paul in the woods]

I know a few people locally that might be able to help but they're both sheltering from Covid at the moment.

 

Many thanks for the offer Doobin, I do have family over there but will not be that way for a while.

 

Thankfully I'm not in any rush and I'd like to get something sorted as I can see it happening again.

 

Thanks for the warning Bob, that is also my main concern with a normal die, and making the matter worse. I couldn't find an M30 rethreading tap and I'd expect one would cost and arm and most of a leg.

 

I might go back to the file thread restorer to start with. I had thought about going in from behind, so to speak, but I don't think there's enough room to get the bolt through.

 

I'm sure the might be something else I've not thought of. There does seem to be a few sensors and even sump plugs that are M30 x 1.5 but not many bolts or other tools. Ideally I could do with a min 60mm long bolt even if I use the file, so I can test the thread.

[Paddy1000111]

Always worth asking round. I had an issue with a hydraulic line thread before and I rang about asking for taps etc. The engineer at Pirtek let me take the tap, fixed what needed to be fixed then drop it back. I returned it attached to a bag of doughnuts... 

[Dan Maynard]

 

perhaps you could find another metric tap with 1.5mm pitch and use it as a scraper to reform the thread.

The form on a standard M10 X 1.5 tap will be exactly the same, so this can work as a scraper. I've done something similar on a 0.5 pitch on a cycle rear wheel, obviously that was aluminium and not as deep so I could see what I was doing.

[Macpherson]

1 hour ago, Dan Maynard said:

The form on a standard M10 X 1.5 tap will be exactly the same, so this can work as a scraper. I've done something similar on a 0.5 pitch on a cycle rear wheel, obviously that was aluminium and not as deep so I could see what I was doing.

Yeah, it seams that I spent half my working life repairing threads,,, often you need to be inventive to save something that's otherwise very expensive scrap and or just too hard to find a replacement part.?

[Paul in the woods]

I had thought about getting an undersized bolt, but it would need to be M29 which doesn't seem to exist. I'm currently looking through some plumbing fittings as they around that size.

[bmp01]

This might be totally inappropriate but I'll say it anyway .... could you live without the first few threads entirely? Machine a counter bore or Dremmel damaged threads away and survive on remaining good thread.

Sounds a bit rude, but consider that the damaged threads might not be taking any useful load anyway depending on the thread restore technique. 

 

[Paddy1000111]

Is the part removable/handle-able? If it was me I would take it off and ring a few engineering companies and ask. Some may charge you, some may not usually deal with small jobs and it would become a "tea-time" job for a machinist in return for a little cash or some beer...