3.2 MM Spoke - Find A Tap?

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NATURAL ANKLING
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3.2 MM Spoke - Find A Tap?

Postby NATURAL ANKLING » 15 Sep 2019, 11:10pm

Hi,
(Honda)
Spoke is 3.2 mm on the shaft.
Thread OD is 3.5 mm.
40 TPI
Original nipples are 6.6 dia (plain portion)
From the chart its 8 swg thread, and the spoke shaft is between 8 & 9 swg (5/32 on chart)?
Online they call it 10 gauge nipples? (for 3.2 mm spoke 6.4 mm dia nipple)
I want a tap to clean out the nipples?
(some corrosion in nipple threads where thread is bare, I am rebuilding wheel)
Can you even get one and what's its size etc.
Might have to buy some nipples.

https://www.motalia.com/Html/Charts/cycle_chart.html

2019-09-15_203133_a.jpg
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Brucey
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Re: 3.2 MM Spoke - Find A Tap?

Postby Brucey » 16 Sep 2019, 12:36am

they do sound like 10G spokes to me. Not sure where to get a tap from.

cheers
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NATURAL ANKLING
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Re: 3.2 MM Spoke - Find A Tap?

Postby NATURAL ANKLING » 16 Sep 2019, 10:22am

Hi,
Do they exist maybe not outside s nipple factory, I am assuming that nipples are tapped?
But how do we arrive at 10 g?
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Re: 3.2 MM Spoke - Find A Tap?

Postby Brucey » 16 Sep 2019, 11:39am

10g comes from SWG (standard wire gauge) definitions. If there is some underlying rationale behind SWG I don't know what it is exactly.

The usual 10G spoke thread is 44tpi, and this isn't terribly close to any metric thread pitch. I was wondering if there was an M3.5 thread that was close enough to bodge, but it looks like no.

Taps must exist but they would have to be pretty unusual items { I once asked some time served machinists about taps for spoke threads; after half an hour's measuring and muttering, they concluded that the threads were 'special', and no, they had never seen taps that size}. IME if a brass thread is damaged, since retapping just removes metal, it won't cure every kind of damaged thread. I'd also note that damage to the spoke thread is also likely; you don't usually damage one without damaging the other.

cheers
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NATURAL ANKLING
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Re: 3.2 MM Spoke - Find A Tap?

Postby NATURAL ANKLING » 16 Sep 2019, 12:09pm

Hi,
Yeh sorry, spoke shank is 3.2 mm so in between 8 & 9 swg, nipple is 10 g?

No damage much to spokes, slight corrosion on threads (steel).
Nipples are steel plated.

Corrosion in unused threaded portion of nipple where spoke is short, Binds where it hits when I rebuild wheel.

Tensioning ?
Stress relieving?
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Re: 3.2 MM Spoke - Find A Tap?

Postby Brucey » 16 Sep 2019, 12:16pm

NATURAL ANKLING wrote:Hi,
, spoke shank is 3.2 mm so in between 8 & 9 swg, nipple is 10 g?



eh?

What chart are you looking in? 10g in SWG is 3.251mm

FWIW brass can usually be cleaned of corrosion product using chemicals, eg a weak acid. I'd try that.

I'd also note that a smaller tap with the correct (44tpi ?) pitch can be used as a scraping tool inside a slightly larger diameter thread; ths might be good enough?

cheers
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NATURAL ANKLING
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Re: 3.2 MM Spoke - Find A Tap?

Postby NATURAL ANKLING » 16 Sep 2019, 12:23pm

Hi,
:oops: stupid me I was using the posted thread table.
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Re: 3.2 MM Spoke - Find A Tap?

Postby NATURAL ANKLING » 16 Sep 2019, 5:06pm

Hi,
I have a load of old Spokes at hand.
Just ground some flats on the threads, A bit of cutting oil and run it through.
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DanZac
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Re: 3.2 MM Spoke - Find A Tap?

Postby DanZac » 17 Sep 2019, 6:36am

Brucey wrote:10g comes from SWG (standard wire gauge) definitions. If there is some underlying rationale behind SWG I don't know what it is exactly.

The usual 10G spoke thread is 44tpi, and this isn't terribly close to any metric thread pitch. I was wondering if there was an M3.5 thread that was close enough to bodge, but it looks like no.

Taps must exist but they would have to be pretty unusual items { I once asked some time served machinists about taps for spoke threads; after half an hour's measuring and muttering, they concluded that the threads were 'special', and no, they had never seen taps that size}. IME if a brass thread is damaged, since retapping just removes metal, it won't cure every kind of damaged thread. I'd also note that damage to the spoke thread is also likely; you don't usually damage one without damaging the other.

cheers


I've not got the right size tap to try but No 5 UNF looks like it might be pretty close.

https://britishfasteners.com/threads/unf.html

Brucey
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Re: 3.2 MM Spoke - Find A Tap?

Postby Brucey » 17 Sep 2019, 11:22pm

#5 UNF is the correct pitch but the major diameter of that thread is slightly smaller (0.125") than the 10G wire diameter (0.128"). The spoke thread is rolled onto this diameter which raises the thread tops above the 10G diameter, i.e. the 10G spoke thread is about 0.138" major diameter. Thus #5 UNF is close but a bit too small.

cheers
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