Thread identification

Any chance it's 1BA?

Cheers Tim

Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service

Try WNT in Sheffield. Mark.

In article , Steve writes

Machinery's Handbook describes UNS threads as being threads for special purposes not falling into the regular (UNF, UNC etc.) series, but using the same design parameters. 10-28 UNS is included there as you describe, with full thread parameters. I assume you found those, if not ask and I will transcribe them (won't unless you ask, very tedious detail).

Your options would probably be (1) make a tap yourself, (2) search for a supplier, probably from the USA, or (3) bore out and re-tap with an available thread size. Of course, this being a very resourceful group, someone may just have one lying around their workshop....

David

Thanks Chaps

David, I found the spec for UNS on the web, so I don't need it sending thanks. I want to tap some bits to fit existing parts.

I hadn't thought of 1 BA which at 0.9mm pitch is only 0.0003" finer than

Mark, I don't know WNT but will look.

All very helpful, thanks again.

Steve (Sheffield)

What's the *actual* exact o/d of the male thread to within a thou or so? If it's really a 3/16" male thread it'll be a good few thou less than nominal

What's the pitch angle? 60 degrees for metric and UN threads and 47.5 for BA will help narrow it down.

Scientific equipment tends to use BA threads. That's what they were designed for. 1BA has the right pitch but is way over 3/16" unless you're telling us porkies about the o/d.

Dave

Just been back in the 'shed'.

Actual diameter of male thread is around 0.187" or 4.75mm depending on where on the length you stick the caliper.

I have examined the thread with a magnifying glass and a 60 degree thread pitch gauge. I am still unsure of the thread angle, but I don't have a decent method of measuring it. (I was aware of BA 47.5, Whit forms at 55 and metric and UN at 60 though thanks)

Looking through the glass, the 28tpi gauge is slightly coarser than the existing piece. This is visible over about 16 pitches, being the full length of the gauge. 1 BA is 0.209" x 28.2tpi which is of course slightly finer than 28tpi. The measured thread is thus 22 thou down on this, which does seem a lot.

Steve

In article , Steve writes

Steve

Where do you live? I have a toolmaker's microscope, just the job for measuring angles etc. on odd threads.

David

David

I'm in extreme North of Sheffield Sorry for being non specific to whole group but you can't be too careful. Also for not responding sooner, had to go to bed! Not sure what to do about the nospam in your mail address or I'd write directly, the address for me in this message works though.

I have looked at them (microscopes) and most other things engineering on Ebay, but you can't have everything, however much you'd like it, even for your hobby!

It certainly is a rascal thread! I do have some other pitch gauges in the shed I'd forgotten I have. Will try them and report any findings.

Phone is 0114 2884223

Steve

In article , Steve writes

OK, I'm in London, so that would not be practical. However, there are some quite decent hand-held illuminated magnifiers with interchangeable graticules (the ones that look like a torch with a film canister on the end). At least one of the commonly-found graticules has a protractor on it. I have one of these as well, cost about £20, and should serve as a poor man's TMM (though I don't recall trying it for this precise purpose). You'd probably have to grow a third hand or stick one or other part in a vice.

David

As promised below.

Found my other pitch gauges, I didn't remember I had them until I was in bed last night.

The 0.9mm pitch fits well. I have just found that it is the same overall diameter as a cheap commercial 5mm x 0.8mm setscrew.

I think it must be an anorexic 1BA. Still can't determine the thread angle though.

Steve (Sheffield)

Why do you keep your pitch gauges in bed ? Do you turn in your sleep ?

-- Regards,

John Stevenson Nottingham, England.

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Aren't they screw pitch gauges?

Must be a water bed if it's pitching that much.

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

You varmints!

They are screw pitch gauges and they live in the drawer under the DW vertical miller. I had been using a less comprehensive gauge from a cheap set of taps and dies, because I had forgotten the others were in the same drawer. (Senile at 51) I remembered them after hitting the sack last night, but couldn't be bothered to get up, get dressed and go outside to the cold 'shed' at the time.

Yes, I do spin round like a propeller in my sleep and get into trouble for wrapping the quilt round me. Apparently I hurl myself over and disturb her. Sadly not a water bed, just coils with little or no damping, but too little 'screw pitching' these days! You've got to laugh!

I must say this group provides me with constant amusement, guys who make things are generally likeable and there is always a bit of banter flying. Keep up the good work.

Steve Sheffield

Thanks David and everyone else

I know what you mean with the torch/cannister thing - I've seen them. I do have a microscope, which was a Christmas present when I was a lad, but haven't had it out of the box for donkeys years.

Steve

In article , Steve writes

Steve,

A toolmaker's microscope is a long way removed from a "normal" microscope (which is itself a broad category). It will usually have a very large rotating glass-centred steel table, with T-slots for holding accessories, and with verniers to measure angle, and X and Y micrometers to measure the movement of a reference point observed by a graticule in the eyepiece. Very solidly constructed, the whole lot probably needs two people to move it.

David

Gents

Have had the microscope on the case. The threads are badly damaged at the end and look to be 60 degree, but where they are not worn they are much a narrower angle looking more like they might be 47.5. I'll make a 1 BA nut this weekend.

Steve (Sheffield)

Steve

If you have your microscope going now, how about comparing thread angle with threads of known angle, perhaps even a tap? Just a thought.

Mike

In message , Steve writes