Friday, May 22, 2020

Lockdown Project: Windmill repair

Some jobs should be simple and turn out to be anything but. We have an ornamental windmill in the garden. I think it turned up last year. What I do know is the sails fell off. Somehow the nut holding them on vanished.

All I had to do was replace it surely?

Not a chance. Nothing in the garage would fit, and since this is over 100 feet away from the windmill, I got fed up walking back and forth. Taking the pivot off the front proved to be the first challenge, involving removing more wood and metal than expected. Never mind, it's only 4 cross-head screws.

This is the problem. No nut in my collection fits better - and that includes those rusty ones in Golden Flake tobacco tins. Those tins that just appear in garages and workshops. Well, the sort of garages and workshops I like.

Right, out with the big tap and die set. The nearest to the threads is a 1/8NPT27. I have no little what this means and it does seem to be an oddity in an otherwise metric set. I have a metric set because I have old VWs and if you find an imperial nut, it's wrong and you should throw it away.

Anyway, I ran it down the threads on the spinny bit. I don't care if it's wrong, I just want a matching nut and bolt. It ran down nicely though so can't be very far off. Next, I tapped the nut to match. This isn't pretty so I didn't take a photo. Not sure the Nylock insert will be much good now, but then this isn't exactly critical work.

A washer is a good idea, but of course, I can't find one with a big enough hole. I can find my old tapered reamer and this far it (I used to use it for model bearings so used the pointy end) is perfectly sharp enough to open up a hole in a nice big washer.

Someone will tell me holding the washer in mole grips is bad. It worked though.

Anyway, after all this and a few minutes work with sockets and screwdrivers, the windmill is repaired. The sails spin and it looks lovely again.

I'll probably find the lost nut now.


Anonymous said...

Your 1/8 NPT 27 is an (American) National Pipe Thread with 27 TPI for 1/8" pipe.

I suspect your thread may actually be an ISO Metric Fine thread of 8mm dia by 1.0mm pitch. The more common standard metric 8mm thread has a 1.25mm pitch.

Brian G

I.A.Cooper said...

I'd suggest your windy-mill turns with an American accent (as does your tap set!)....

1/8" NPT would be 1/8" National Pipe Thread, which is 27 threads per inch: Hence "1/8NPT27"

This is the USA equivalent of 1/8" British Pipe Thread, which is the standard in the UK, and to a certain extent still across Europe for pipe fittings as well.

The outside diameter of the thread is sized to be suitable to put on a pipe having a bore of 1/8".

Now as to why a pipe thread was used in a garden ornament that isn't related to pipe fittings is another question! Both 3/8" UNF and 7/16" UNF are both fairly fine threads as well (24tpi and 20tpi)

Luke said...

"1/8NPT27" is an 1/8 diameter pipe with 27 threads per inch. NPT is am american standard, often called "national pipe thread" standards." (Wikipedia)
The die shouldn't be in a metric set but seem to be about 3mm

Paul B. said...

That die's for a pipe thread. Quite why you'd need one in a set of metric taps + dies is beyond me...
Standards are great - everyone wants their own. Put simply, we started out with anarchy (everyone using their own), then Whitworth for coarse thread and BSF (British Standard Fine) for, well, fine. Then came along UNF/UNC (Unified National Fine/Coarse), which we adopted to please our American chums. At some stage we realised that we're part of Europe, so we went metric. So, four different standards in use, not to mention all the special purpose thread standards that have appeared over the years. Even metric isn't that simple, with up to 4 different pitches per thread diameter. Confused?
Your windmill looks like it has a fine thread, so possibly UNF.