Spoke Nipple failure

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Re: Spoke Nipple failure

Postby Mick D » Sat Nov 16, 2019 11:50 am

Hi

I measured as you would a countersunk screw - from the widest part of the countersink to the end of the thread:

Spoke Dim.png


Regards Mick
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Re: Spoke Nipple failure

Postby alanengineer » Sat Nov 16, 2019 1:17 pm

super photo from Mick. The hub almost laces the wheel for you. Easiest wheels i have ever built but lacing is only the start. Its easy to true the rims badly and you do need a jig, however simple

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Re: Spoke Nipple failure

Postby Mick D » Sat Nov 16, 2019 1:34 pm

alanengineer wrote:you do need a jig, however simple


I can do simple ;)

Wheel Jig.png
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Re: Spoke Nipple failure

Postby asterysk_usa » Sat Nov 16, 2019 2:47 pm

Mick D wrote:Hi

I measured as you would a countersunk screw - from the widest part of the countersink to the end of the thread:

Spoke Dim.png


Regards Mick


Looks like you have identified the problem, my spokes are too short.

I checked my original order with DRC and it was for AMC2-SSP and AMC3-SSP , I'll discuss with them and give them the lengths that you are using
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Spoke Nipple failure

Postby asterysk_usa » Tue Nov 19, 2019 4:07 am

I checked with DRC and my spokes are the correct length. I can get slightly longer spokes made but they will be special order.

I at a loss now what to do, do I just order new nipples and assume that the original wheel build was overtightened or do I special order longer spokes , if so how much longer !

so I have a few questions for the wheel experts that will help me decide:

1) If the spokes are too long i.e. poke through the nipple, is it easy to grind them back and does this cause any issues ?

2) If I go for longer spokes, should I also make the threaded portion longer ?

3) Is there a technique using the hub and rim, to determine what the ideal length of spoke should be

4) Is there a way using my existing spokes and nipples to do a test lacing and use this somehow to determine the best spoke length
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Spoke Nipple failure

Postby alanengineer » Tue Nov 19, 2019 9:42 am

I built some wheels with spokes and nipples supplied by central wheel. The spokes were 1/8"- 3/16" too long Their are 2 problems with this. 1 you have to grind the top off the spoke, not a great problem. " the threaded portion of the spoke runs out and it bottoms out in the nipplel so you force the plain uncut part of the spoke into the threaded part of the brass nipple and that is not good.

If i were in your position, i would carefully unlace the wheel and take all of the spokes out. Check the spokes for straightness/trueness and re-lace it using the idea of the good photo published earlier. the spokes will point to the correct hole and the piercing in the rim should be angled correctly to accept the spoke with minimum deflection. Tighten up the spokes as a test run and check the lengths

If the spokes are true, i would reuse them, but would discard the nipples and get a new set.

I cant remember, but the rear wheel might have different length spokes on either side to accommodate the offset. Oh, check that first before you take the wheel apart!

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Re: Spoke Nipple failure

Postby DM2 » Tue Nov 19, 2019 11:43 am

Or try calculating the spoke lengths -

http://earlymotor.com/leon/misc/html/spoke.htm

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Re: Spoke Nipple failure

Postby Mick D » Tue Nov 19, 2019 4:48 pm

Hi

When I built my wheels using all new DRC components the spokes all fell just short of protruding through the nipple.

I'd follow alanengineer's advice, strip and carefully re-build with new nipples - my money's on either over tightening or poor rim alignment causing the failures.

When I 'ring' my spokes I aim for a nice musical ding - the one just above the thud - you'll recognise it when / if you do it, a ping is too tight in my opinion.

Regards Mick

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