# 16 g thread type help please



## Covert (25 Nov 2018)

So in wiring up my myford to actually run forwards and backwards I'm using the original metal corrugated tubes to get the wires from the front to the back of the stand . But I need some nuts for them . 

Measured the thread and it comes up at 16g Whitworth. And then in very small writing 3/8 . 

Silly question but if I buy some 3/8 Whitworth half nuts will these fit ?

Thanks for the help
Mark


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## J-G (25 Nov 2018)

Covert":2qch6mgy said:


> So in wiring up my myford to actually run forwards and backwards I'm using the original metal corrugated tubes to get the wires from the front to the back of the stand . But I need some nuts for them .
> Measured the thread and it comes up at 16g Whitworth. And then in very small writing 3/8 .
> Silly question but if I buy some 3/8 Whitworth half nuts will these fit ?



I've never seen a thread description that confused me so much but after a period of 'thinking out of the box' I have to assume that you mean that you have used a thread gauge and determined that what you have is 16 *TPI*. If that is the case AND the diameter is just shy of 0.375" then the chances are high that it is 3/8" BSW - (being Myford it's unlikely to be 3/8" UNC).

Just stating 3/8 Whitworth doesn't say enough. If you just specify 'Whitworth' then you are only referring to the thread form (55° flank angle)


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## AndyT (25 Nov 2018)

Yes.
If you look at a chart such as this one https://motalia.com/Html/Charts/bsw_chart.html it confirms that 3/8Whit has 16 threads per inch, which will probably be marked as 16G on a thread gauge. See the current thread on a Wolf grinder for a gauge marked like that.


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## DTR (27 Nov 2018)

The thread gauge assumes a standard Whitworth size, hence the "3/8". However I expect that your conduit's diameter is a lot bigger than that. As J-G says, all we know is that it's 16tpi. We need to know the outside diameter before we can guess what nut it takes. We can rule out BSP (British Standard Pipe) as there are no 16tpi threads in that range. I suspect it's a standard imperial conduit thread, but I haven't got my thread tables to hand. If I remember I'll have a look when I get home.


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## AndyT (27 Nov 2018)

Go by what J-G and DTR said and check the diameter as well. I left that important bit out of my answer


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## J-G (28 Nov 2018)

DTR":1e48624l said:


> The thread gauge assumes a standard Whitworth size, hence the "3/8". However I expect that your conduit's diameter is a lot bigger than that. As J-G says, all we know is that it's 16tpi. We need to know the outside diameter before we can guess what nut it takes. We can rule out BSP (British Standard Pipe) as there are no 16tpi threads in that range. I suspect it's a standard imperial conduit thread, but I haven't got my thread tables to hand. If I remember I'll have a look when I get home.



Conduit thread standards do have 16 tpi in (Nominal) 3/4", 1" & 1-1/4". Regrettably, I can't find details of the actual sizes - even digging into my Grandfather's copy of Machinery's Handbook (1923 Edition)! 
The Pg range (DIN 40430) list also has 16tpi but only from Ø1.114" to 2.335" that is Pg21 to Pg48. Although Pg threads are now deprecated, at the time that the Myford was built it could have been used.

Myford are not known for sticking to 'standards' and often used whatever took their fancy, so they could have used ½" BSF or even any of the 6 ASME threads that have 16tpi - 20, 22,24,26, 28 or 30 -- good luck finding nuts to fit them !!

And of course it could just be a 'mongrel', though I think that unlikely.


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## AndyT (28 Nov 2018)

I guess the good news is that the OP has a lathe so might enjoy making his own nuts to fit!


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## DTR (28 Nov 2018)

J-G":6km8jofj said:


> DTR":6km8jofj said:
> 
> 
> > The thread gauge assumes a standard Whitworth size, hence the "3/8". However I expect that your conduit's diameter is a lot bigger than that. As J-G says, all we know is that it's 16tpi. We need to know the outside diameter before we can guess what nut it takes. We can rule out BSP (British Standard Pipe) as there are no 16tpi threads in that range. I suspect it's a standard imperial conduit thread, but I haven't got my thread tables to hand. If I remember I'll have a look when I get home.
> ...



I hit the same dead end, no reference to conduit threads in any of my old books :? The only thing I didn't look in was the Zeus book.


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## AndyT (28 Nov 2018)

Does this chart help? If the OP can confirm the OD of the conduit, it gives the spec of the nuts, doesn't it?

http://www.oldengine.org/members/diesel ... nduit1.htm


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## J-G (28 Nov 2018)

Well !!

It seems that we are all over-thinking the issue.

From a little more research (I feel like a dog worrying a bone  ) I've found a web-site - - - http://136.243.43.77/~itccgroup/public/ ... %20new.pdf (scroll down to page 4) - - - which indicates that BS31 uses the *O/D* of the pipe as the designation, rather than the bore diameter as in the BSP standard.

I presume that since a 'Conduit' is not carrying a liquid or gas, then the I/D is not critical.

I suspect that back in 1965 (ish) when I was dealing with all manner of threading questions on a daily basis (working for Herbert Small Tools) I could have told you this without batting an eyelid. Some knowledge is retained but obscure stuff needs research.


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## J-G (28 Nov 2018)

AndyT":n6drfaha said:


> Does this chart help? If the OP can confirm the OD of the conduit, it gives the spec of the nuts, doesn't it?
> 
> http://www.oldengine.org/members/diesel ... nduit1.htm


Yes, Andy, (our posts crossed) it confirms what I found out.

Take the 3/4" - with a core diameter of 0.67" and a 0.04" depth of thread that makes the OD 0.75" ie. 3/4" !


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## Vann (28 Nov 2018)

I've refitted steel conduit to one of my machines, and intend to use steel conduit on two more (when nearing completion). British Standard Conduit threads are 18tpi for 5/8" conduit (I think 5/8" is the nominal internal diameter) and 16tpi for 3/4" and 1". I managed to pick up a set of BS conduit dies. 
I've been collecting conduit fittings from old buildings for around two years to provide elbows, tees and barrel connections - and a few nuts - but good luck with that.

http://www.oldengine.org/members/diesel ... /mech1.htm

I had to make one nut which I filed hexagonal from a bit of 5mm plate, after tapping 3/4" BSC. There are a couple of 3/4" BSC taps on Epay at present.

Cheers, Vann.


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## Covert (28 Nov 2018)

Appologies for the confusing post should have put some pictures


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## AndyT (28 Nov 2018)

Well, the table shows 1" conduit having 6 tpi so I guess you need to find or make some 1" Imperial conduit nuts, to the dimensions on the right hand side of the table.
A nice intro to boring and internal thread cutting!


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## Covert (28 Nov 2018)

Anyone fancy making a pair lol ?


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## J-G (28 Nov 2018)

AndyT":18qq8017 said:


> Well, the table shows 1" conduit having *6 *tpi ...


Obviously a typo Andy - I see *16*


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## AndyT (28 Nov 2018)

A slip indeed - sorry - and thanks!


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## J-G (28 Nov 2018)

Vann":3khd3m6c said:


> I had to make one nut which I filed hexagonal from a bit of 5mm plate, after tapping 3/4" BSC.



One should be careful when contracting a thread designation. BSC is the contraction for British Standard CYCLE rather than Conduit though to be fair it is usually followed by CEI


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## Vann (29 Nov 2018)

J-G":3m6ck64q said:


> Vann":3m6ck64q said:
> 
> 
> > I had to make one nut which I filed hexagonal from a bit of 5mm plate, after tapping 3/4" BSC.
> ...


Yeah, I was taking shortcuts as it was time to leave for work (I see I also posted a link that had already been posted 'cause I didn't read all the preceding replies properly, in my hurry  ).

Cheers, Vann.


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