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Help identifying thread

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Chris Shelton16/05/2020 11:32:38
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92 forum posts
46 photos

Hi I have a thread on an American made car diagnostic probe, which I am having trouble identifying, the major diameter is 4mm or .1580" it is 32tpi. can anyone help, I need to purchase a tap to suit, have looked on the internet, but cannot match the details.

Thank you

Tony Pratt 116/05/2020 11:44:12
1230 forum posts
5 photos

Most likely 8-32

Tony

Marischal Ellis16/05/2020 11:48:29
68 forum posts
27 photos

poss UNF does that help.

mechman4816/05/2020 12:19:49
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2749 forum posts
423 photos

Try:-

ANF ( 60* ) #10 = 32TPI

2 BA = 4.0 mm / 0.1575

George.

Chris Shelton16/05/2020 12:21:47
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92 forum posts
46 photos

Hi, Thank you for the replies, just found my engineers Black Book, and it looks as if it could be 5/32 BSW, which is not listed in Zeus

Tony Pratt 116/05/2020 12:34:56
1230 forum posts
5 photos

Hi Chris, 2 points, the yanks would not use BSW & .158" is bigger than 5/32" that being said it will work.

Tony

Clive Brown 116/05/2020 12:37:08
503 forum posts
18 photos

5/32" BSW is Meccano thread. Seems unlikely on an American gadget.

Andrew Johnston16/05/2020 12:42:24
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5660 forum posts
653 photos

Given it's US made I'd bet it's 8-32 UNC.

Andrew

Howard Lewis16/05/2020 12:55:37
3605 forum posts
2 photos

Zeus Charts give 6-32 ANC as having an OD of 0.138", and 8-32 as 0.164" The thread form will be 60 degrees

There is no ANF thread with 32 tpi pitch.

It could be 10-32 UNF which is 0.164" diameter, but slightly truncated to give the 0.158" OD.

If it were 4mm it would be 0.15748" diameter, but M4 is 0.7mm pitch which is 17.78 tpi.

HTH

Howard

Jeff Dayman16/05/2020 13:08:49
1894 forum posts
45 photos

Howard Lewis - your third sentence - #10-32 UNF is NOT .164" diameter, #8-32 UNC is .164" diameter

#10-32 UNF is .190" diameter

Howard Lewis16/05/2020 13:16:35
3605 forum posts
2 photos

Quite RIGHT,

I misread from one line to the next

Sackcloth and Ashes again!

So looks like 8-32 UNC as a likely candidate.

Howard

Chris Shelton16/05/2020 13:24:56
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92 forum posts
46 photos

Thank you all for taking the time to reply, I have ordered a 5/32 BSW set of taps, as Tony P said it will work.

Tony Pratt 116/05/2020 13:49:17
1230 forum posts
5 photos
Posted by Chris Shelton on 16/05/2020 13:24:56:

Thank you all for taking the time to reply, I have ordered a 5/32 BSW set of taps, as Tony P said it will work.

If it doesn't work I will refund your moneycheeky or send you an 8-32 tap.

Tony

Edited By Tony Pratt 1 on 16/05/2020 13:49:57

Pete Rimmer16/05/2020 13:53:28
778 forum posts
50 photos
Posted by Howard Lewis on 16/05/2020 12:55:37:

Zeus Charts give 6-32 ANC as having an OD of 0.138", and 8-32 as 0.164" The thread form will be 60 degrees

There is no ANF thread with 32 tpi pitch.

It could be 10-32 UNF which is 0.164" diameter, but slightly truncated to give the 0.158" OD.

If it were 4mm it would be 0.15748" diameter, but M4 is 0.7mm pitch which is 17.78 tpi.

HTH

Howard

Sorry to be a correction-ist Howard but I think you multiplied instead of dividing there. 0.7mm pitch would be 36.28tpi

Barrie Lever16/05/2020 14:57:10
688 forum posts
76 photos
Posted by Chris Shelton on 16/05/2020 11:32:38:

Hi I have a thread on an American made car diagnostic probe, which I am having trouble identifying, the major diameter is 4mm or .1580" it is 32tpi. can anyone help, I need to purchase a tap to suit, have looked on the internet, but cannot match the details.

Thank you

That is a slightly shy 8/32 UNC, no way would the yanks use 5/32 whit, they would have no need to.

B.

Neil Wyatt16/05/2020 15:15:25
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Moderator
18232 forum posts
714 photos
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This is a great explanation of the different systems from an American perspective.

www.rustmag.com/gear/2018/1/4/threads-and-thread-systems

With one exception UNC and Whitworth are the same, except for the flank angles.

Neil

<edit> I forgot the link!

Edited By Neil Wyatt on 16/05/2020 15:15:59

Chris Shelton16/05/2020 17:23:33
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92 forum posts
46 photos

A local friend came to my rescue with a 5/32 BSW tap, after tapping the part it screwed onto the probe about half a turn, so have now ordered, an 8-32 tap, can someone tell me what the 8 in the 8-32 stands for?

Tony I will not hold you to your promise of a refund, after all I could tap some Meccano parts now.

Barrie Lever16/05/2020 17:51:30
688 forum posts
76 photos

Numbering system

8x0.013+0.060 = 0.164"

10x0.013+0.060 = 0.190"

Dont ask me why.

B.

JasonB16/05/2020 17:53:08
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Moderator
18875 forum posts
2078 photos
1 articles

below 1/4" dia UNC & UNF use a number system a bit like old wood screws and BA threads, the higher the number the larger the thread.

Tony Pratt 116/05/2020 18:33:14
1230 forum posts
5 photos
Posted by Chris Shelton on 16/05/2020 17:23:33:

A local friend came to my rescue with a 5/32 BSW tap, after tapping the part it screwed onto the probe about half a turn, so have now ordered, an 8-32 tap, can someone tell me what the 8 in the 8-32 stands for?

Tony I will not hold you to your promise of a refund, after all I could tap some Meccano parts now.

Thanks, let us know if the 8-32 does the trick, 5/32 BSW is slightly smaller on diameter, maybe that is the problem.

Tony

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