What Size Bolts Have I Got ?

[The Coal Man]

Hi,

Would anyone please be able to help me identify what size bolts I have?

I have attached a picture below of two bolts that are almost identical in diameter and head size, I think one is a replacement and the other is an original.

The dimensions of the bolts are:

Original (brass coloured shank)
Threads per inch = 12
Outer diameter of shank across threads = 12.4mm
Width across flats of head = 19mm
No lettering on head

Replacement (grey coloured bolt)
Threads per inch = 12
Outer diameter of shank across threads = 12.5mm
Width across flats of head = 18.9mm
Lettering on head = TA FU


The bolts come from a clamp that secures a rotational actuator to a pole, manufactured either in the Far East or USA approximately 25 to 30 years ago.


Thanks

 

[Pete.]

1/2" Whitworth looks like. If they were 13tpi they would be UNC.

 

[The_Yellow_Ardvark]

As above, imperial.
No head markings mean they are a low strength bolt. Like a metric 4.9.

 

[The Coal Man]

1/2" Whitworth looks like. If they were 13tpi they would be UNC.

Pete, Yellow Ardvark,

Thx for the quicky reply, most appreciated.

A quick search on eBay shows there are supplies available. Would anyone please be able to advise me if eBay prices are reasonable or are there better options available? I am assuming my local hardware store might not stock 1/2" Whitworth nuts and bolts, however, having never bought any before I am not sure?

Lastly, can anyone please recommend a basic thread gauge that counts the threads per inch, every time I try to measure this with a ruler and magnifying glass it is a pain, my eyes are not what they were decades ago.

Thanks

 

[brightspark]

http://www.ebay.co.uk/itm/like/1919...=9046800&device=c&campaignid=628893806&crdt=0

 

[colnerov]

Hi, As they originate from the USA (and possibly your wonky eyes) they could be 1/2" UNC.

Colin

 

[rtbcomp]

A pitch gauge should show the thread form as well as pitch and depth.

 

[The_Yellow_Ardvark]

http://www.namrick.co.uk/
They are good, recommended from this site.
Helpful on the phone.

 

[dan.taylor.1]

Get yourself some pitch gauges and a zeus book as it lists a lot of common and old thread info.

 

[The Coal Man]

Hi, As they originate from the USA (and possibly your wonky eyes) they could be 1/2" UNC.

Colin

Colin,

My wonky eyes are UK peepers, made wonky by age or too much time in front of a computer screen, possibly shrivelled up a bit by a little too much time in pubs. I think I need to get a set of thread gauges make life easier.

Thx

 

[The_Yellow_Ardvark]

https://app.box.com/s/4ulzu8egtjin3etmkyj5

Zeus book on line as a PDF form.

 

[The Coal Man]

Get yourself some pitch gauges and a zeus book as it lists a lot of common and old thread info.

Dan,

Thanks, I found the Zeus book on the "Namrick" site.

Rgds

 

[The Coal Man]

https://app.box.com/s/4ulzu8egtjin3etmkyj5

Zeus book on line as a PDF form.

Even better, a freebie.

Thx

 

[The_Yellow_Ardvark]

@The Coal Man
Yes, free.
I found that when I found my Zeus tables had bean converted.

Converted into what I here you say.

A mouse nest.

along with the cloth bag of my Mike, leather case for the ruler and half a wooden go no set.

 

[Agroshield]

1/2" Whitworth looks like. If they were 13tpi they would be UNC.

Assuming the 12 tpi quoted by OP is correct, if they were truely 1/2" BSW, they would surely have a BSW a/f hexagon on them and not the 3/4" (19mm) as reported by the OP. BSW hex table is on the same Wikipedia page as thread chart.

The reason for this pedantry is that if he buys a 1/2" BSW replacement, the head size may possibly be too big depending on where the bolt goes.

Given there is the possibility of far-East origin, they are likely non-standard - Whitworth thread form but metric a/f head. I have seen the same thing on two 6" x 4" bandsaws (one red in colour and badged Sealey, the other green and badged Warco).

As for thread gauges, I use a 52 leaf one by Draper. This does 99% of everything I need with the other 1% covered by a separate one for BA threads.

 

[The Coal Man]

Assuming the 12 tpi quoted by OP is correct, if they were truely 1/2" BSW, they would surely have a BSW a/f hexagon on them and not the 3/4" (19mm) as reported by the OP. BSW hex table is on the same Wikipedia page as thread chart.

The reason for this pedantry is that if he buys a 1/2" BSW replacement, the head size may possibly be too big depending on where the bolt goes.

Given there is the possibility of far-East origin, they are likely non-standard - Whitworth thread form but metric a/f head. I have seen the same thing on two 6" x 4" bandsaws (one red in colour and badged Sealey, the other green and badged Warco).

As for thread gauges, I use a 52 leaf one by Draper. This does 99% of everything I need with the other 1% covered by a separate one for BA threads.

I have ordered a thread gauge so will check before buying new bolts. I think that the diameters I gave were reasonably accurate as I measured them with a vernier caliper. However, counting along the threads on the small length of bolt with a magnifying glass was the tricky part. I checked twice and got 6 threads per half inch but will check again when the thread gauge arrives.


Rgds

 

[Bill Edwards]

The mention of American origin means UNC springs to mind but anything is possible if it could be from the far East - lets hope they are something normal!

You're doing the right thing though by getting a thread gauge. Heck, it takes me a while to be sure sometimes with a gauge but without...

@The Coal Man
Yes, free.
I found that when I found my Zeus tables had bean converted.

Converted into what I here you say.

A mouse nest.

along with the cloth bag of my Mike, leather case for the ruler and half a wooden go no set.

Rotten rodents.
Blasted things have even been in my house in the past - despite having a rat catching dog!

 

[doubleboost]

It has all been said
1/2 whit or unc

 

[Pete.]

I have ordered a thread gauge so will check before buying new bolts. I think that the diameters I gave were reasonably accurate as I measured them with a vernier caliper. However, counting along the threads on the small length of bolt with a magnifying glass was the tricky part. I checked twice and got 6 threads per half inch but will check again when the thread gauge arrives.


Rgds

You don't need a thread gauge just put a inch rule next to the long bolt. If you count 12 crests to an inch you have 12tpi. Remember the crest where you start is number zero.

 

[Bill Edwards]

You don't need a thread gauge just put a inch rule next to the long bolt. If you count 12 crests to an inch you have 12tpi. Remember the crest where you start is number zero.

Must have good eyesight I think...
I have a comprehensive thread gauge (yet to let me down) but I know when I'm using it, in that it's not that easy for me. The thought of trying to match up to a rule really isn't great.