I need some advice regarding thread types.

[mart]

The nylock nut on my lever hoist has come loose during operation. It is not surprising as I think nylocks are intended for a single use, plus the threads appear to be shot now. It has been removed a few times.

The nut always screwed on anti-clockwise,( left-handed thread). It appears to be 8mm, but I suspect the thread is not standard, as a standard 8mm nut will not screw on. It is likely to be 8mm fine or even 8mm super fine, but until I try a new nut on I won’t know, and this can cause delays. Also, the nut could even be imperial.

Here are my questions so far that I need advising on:

1: Regarding left-handed threads, is it the nut that has the left-handed thread or the bolt/shaft that the nut is being screwed on to? Or, is it both? (I`m guessing it has to be both)?

2: Is AF the same thing as imperial?

3: Does anyone know a stockist in the Sheffield or S,Yorks area etc where I could take my lever hoist, to match the thread on the shaft with the correct nut?

4: Failing this, which online retailer should I try first? I want to crack on with the job that I am using the lever hoist for and don’t want to lose too much time.

 

[RonA]

Answer 1 both
Awnser 2 No AF stands for "across the flats" a way of describing the spanner size based on the unified thread system introduced during WW2 to make American military gear compatible with ours, Imperial dates back to Whitworth the man who standardised threads in Victorian times.
Answer 3 is the thread metric fine rather than the more common metric coarse.
Answer 4 sorry can't help
Hope this helps
RonA

 

[mart]

When I tried the new 8mm nut from my stock, it was a standard right hand thread. Not sure what I was thinking. I was probably not thinking. So, if I am lucky, I could simply buy a left-hand thread M8 nut and be ok without trying to source non metric ones?

 

[mart]

Answer 1 both
Awnser 2 No AF stands for "across the flats" a way of describing the spanner size based on the unified thread system introduced during WW2 to make American military gear compatible with ours, Imperial dates back to Whitworth the man who standardised threads in Victorian times.
Answer 3 is the thread metric fine rather than the more common metric coarse.
Answer 4 sorry can't help
Hope this helps
RonA

I always thought AF stood for Amercan fine, so I am learning from you here. Thank you for confirming that imperial is different to AF. Is Whitworth a different system to imperial or just another name for Whitworth?

 

[mart]

Get a normal M8 bolt and hold it next to the stud and see if the thread has the same amount of peaks over it's length.

Then, you'll know if it's the 'standard' pitch.

I will go and do that now while there is still some light.
I didn`t realise I could do that by the naked eye. I (wrongly) imagined the difference between the thread types would be too subtle to see the actual difference.

 

[rikrobson]

Af means across flat and is a spanner size. Lots of imperial threads have standard spanner sizes and the spanner is quoted by the thread size not the nut size
To correcyly identify the thread youll beed the od and the pitch of rhe thread.
British imperial are 55 degrees and us imperial and metric are 60 degrees.
What make is the hoist. If its us then it going to be unc or unf if its from anywhere else its probably metric unless is uk and old when its whitworth or bnf

 

[ajlelectronics]

AF is neither imperial, nor metric. It is merely a way of describing the distance between the jaws of a spanner, as in "across flats". That having been said, it is typically used to describe Imperial spanner sizes. Whitworth is another imperial thread gauge, like BSF and BA etc.

 

[mart]

I can see the difference in the helix that you referred to while I was out there. The thread of the shaft looks to be the same as the M8 bolt held at the side, except for the different slant of the helix. I`ll order M8 left-handed thread from this ebay seller I found earlier. It`s seems quite quite specific, M8 nylock with a left-handed thread. Maybe more common than what I imagined.

 

[RonA]

I always thought AF stood for Amercan fine, so I am learning from you here. Thank you for confirming that imperial is different to AF. Is Whitworth a different system to imperial or just another name for Whitworth?

The term Imperial refers to the sizes we used in the time when we used to make things in this country i.e. before we gave it all away to China or the japanese.
RonA

 

[mart]

What make is the hoist. If its us then it going to be unc or unf if its from anywhere else its probably metric unless is uk and old when its whitworth or bnf

The brand/make is Speedy hoist.
https://www.speedyservices.com/70_9820-h-pull-lift-6t-swl-1-5m
I have not found out where they are actually made yet.

The staff have been helpful. They can order parts, and it can take from next day up to 10 days.

Last night I bought (from flea bay) Left-hand thread standard size nuts and also some Left-handed thin lock nuts. As yet, I have not been able to source any L/H nylocks. The Speedy services in Sheffield told me of a local supplier for some spares, so I will give them a ring.

 

[mart]

The term Imperial refers to the sizes we used in the time when we used to make things in this country i.e. before we gave it all away to China or the japanese.
RonA

At the steelworks I worked at in the 70s & 80s, management used to bring groups of visitors, showing them around. It is one thing to look at the finished product, but the focus of attention seemed to be on the working machinery & furnaces. There were at times men in suits of oriental appearance. I never noticed the cameras but they were taking notice. My thoughts were that not all the visitor groups would be just potential customers.

 

[Robotstar5]

One of the fitters I worked with in my last job had done his apprenticeship followed by 30 service with Goodyear tyres, all his spanners, sockets etc. were imperial as all the plant he worked on came from the USA , luckily we worked for a good boss who bought him a full set of metric tools