Anyone got a 2 BA left hand threaded machine screw?

What is it out of Chris? I don't have one, but might just one day come up against the same problem and it would be useful to know which way to turn it.

Regards

Alan

It's an air raid siren. Of course one end of the shaft has a right hand thread, and the other a left hand thread. I unscrewed the right handed end first and didn't expect the left handed end. We live and learn!

I think that screw might be a challenge to find.

Chris

2 BA is fairly big. Do you have a lathe?

If not, and you can send me a photo of the old screw I could have a go at making one for you. I should warn you that I am a complete amateur though so it may take a few attempts to get it to work.

2 BA is fairly big as far as fiddly little parts go. Do you have a lathe?

If not, and you can send me a photo of the old screw I could have a go at making one for you. I should warn you that I am a complete amateur though so it may take a few attempts to get it to work, and I can't give any guarantees. Would be an interesting challenge.

Is there a lock nut for it?

The plating and screw slot cutting would be up to you though :)

Alan

Does anybody (e.g. Tracy Tools) do a die, if so it is no problem to run one up for you.

Cheers

Peter

Algern>>>

My father has a lathe which I share. Screwcutting is something I've never tried on the lathe so far. I can send a photograph of the screw if you'd like to have a go, but I wouldn't want you to spend a huge amount of time on it!

Best wishes,

Chris

It seems not, or at least I can't track one down. The Tap & Die Co. (my usual source for such things) don't stock it. I'll let you know if I find one.

Many thanks,

Chris

I'm fairly new to screwcutting myself, and the practice would be good for me. My attempts so far have indicated it is one of those things that is far worse in contemplation than in reality.

Send me a photo and I will see what I can do.

And besides, I owe you for sending me the magneto cover a while back.

Alan

Bear in mind that 2BA is pretty close to 3/16" BSF (and 3/16" BSC or BSB, IIRC), if it's not a highly stressed item then that's probably close enough, if you can find a die.

Cheers Tim

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In article , Christopher Tidy writes

You have e-mail...

Hi Bob,

Sorry I haven't responded to your e-mail. I didn't receive it. Perhaps it went astray or perhaps you didn't notice the spam block in my e-mail address? I apologise for the spam block but it was the only way I could find to reduce the amount I spam I was receiving. I was getting several times as much spam as good messages a year or so ago.

Please post your message to the group or e-mail me at (no spam trap this time, one more occurrence can't hurt): snipped-for-privacy@cantabgold.net.

Many thanks,

Chris

Sorry it has taken me a while to get back to you. I've had a busy week.

Here's a picture of the screw. It's 7/16" long. You can see a bit of the slot damage in the picture:

Don't try to make one just yet. I'm hoping Bob Unitt might have one (apparently he sent me e-mail on this subject, but I didn't receive it, so I'm hoping he reads this group often).

I've also had slight concerns that this might be a left hand threaded ISO metric coarse screw. The slotted cheese head is almost exactly (within about 1/50 mm) of being 8 mm diameter by 3 mm thick. But the major diameter is 4.68 mm, which seems too small for an ISO metric 5 mm screw to me. Of course the pitch of a 5 mm screw is 0.80 mm, and the pitch of a 2 BA screw 0.81 mm, so it's almost impossible to tell from the pitch. I guess the angle of the thread form would be the best way to tell for certain, but I don't know how to measure it accurately. It looks more like 47.5 degrees than 60 degrees to me, but that's just an estimate.

I think if the worst comes to the worst I could enlarge the slot of the screw a little to make it usable. I'll wait to see if I hear from Bob Unitt and keep you informed.

Best wishes,

Chris

Hi Chris,

You're right, I didn't spot your spam-trap :-(

I've re-sent the e-mail to the above address, so it should get through OK this time - if it doesn't, post again here and we'll try something else.

Don't try e-mailing the address in this posting by the way, as it's also a spam-trap...

Hi Alan,

Don't worry about trying to make one for the moment. It turns out that Bob has a left-hand threaded 2 BA die, so we're going to try to make one, or possibly re-machine the slot in my existing screw.

Nevertheless, thanks very much for the offer.

Best wishes,

Chris

Thanks Bob. Got your e-mail. Just sent a reply...

Best wishes,

Chris