Aluminium build up strength

[Pete.]

Put a caliper or a micrometer on it. 14mm is more like 9/16" than 5/8". I should think it would be an imperial thread but if it does turn out to be metric then it will more likely be trapezoidal than acme.

 

[Screwdriver]

Reason I say that is it is closer (by eyeball) on a ruler to 14mm than 9/16 and crucially, it's a modern vice with 90x70mm written on the sticker!

So it's most likely metric though it does have an acme (square) thread...

s.

 

[Seadog]

If it's metric then it will almost certainly be a trapezoidal thread.

 

[Screwdriver]

If it's metric then it will almost certainly be a trapezoidal thread.

Well, you tell me...

S.

 

[Pete.]

You can't tell by looking at it. There's only 1 degree included that's only half a degree per side difference. Put a mic on the OD or a ruler across ten pitches.

 

[Screwdriver]

Thanks for the info. Here we go then.

Diameter of thread is 15.5mm (or 0.61) inch.
Pitch is 3.19mm (0.1255inch)

Is that a standard size metric trapezoidal thread?
How much is a left hand tap?

S.

<edit> could be a 5/8 x 8 tpi imperial acme or TR 16x3 trapezoidal.
How to tell??

 

[Screwdriver]

Incidentally, this is my list of vice restorations.

Found a little billet of bronze (I suspect!) to make up a new nut.

Bought an inch of meehanite/cast iron to make up a retaining ring for the Swindens.

The little "Nippy" (it isn't actually the Nippy brand) vice, fresh from the dip just needs some light fettling.

And that hewge bar of found copper <proud> is going to get chopped up to make soft/welding jaws fro the Swindens. Just as soon as I get bored polishing it

They'll all get their own threads I suspect.

S.

 

[Seadog]

Unless you can measure the thread angle accurately it'll be a guess. The thread standard for 5/8 ACME is 8 tpi. For 16 mm it is 4 mm pitch. Assuming a standard thread it sounds like ACME. Re the tap, I've had no experience of using one, but there are various threads I've seen in the past that suggest it's an almost impossible job to get a single tap through. However, Tracy tools sell them. The thread you have is right hand BTW. - http://www.tracytools.com/5-8-x-8-acme-taps

 

[Screwdriver]

Well I can't measure the angle but 8 TPI (1" screw) thread gauge fits perfectly, the 3mm pitch does not.

I'm calling it.

It's a 5/8" 8TPI Acme.

<scurries off to eBay>

S.

<edit> eBay was out so I bought this: http://www.rdgtools.co.uk/cgi-bin/s...P-5-8--X-8-TPI-HSS--LEFT-HAND--994093458.html

 

[Pete.]

5/8" 8tpi looks the job. For an accurate TPI measure 8 or 16 pitches, should be bang on 1" or 2"

RDG do a tap for £18-odd

 

[Seadog]

But it's a right hand thread as I said in a previous post

 

[Screwdriver]

But it's a right hand thread as I said in a previous post

Dammit! You're right too. How could I be so daft...

Don't answer that!