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A wheelist
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11,324 Posts
Discussion Starter · #1 ·
Hey smart people and engineery types - how do I accurately (to 0.01mm anyway) measure the nipple bed thickness on a rim?

Ok go!

Hmmm, how about a spacer of known length that will go down through the rim bed hole? Now measure (with vernier caliper) from spacer top to rim inner circumference and deduct the spacer length?

I already figured out how to measure the brake track thickness. That maxed me out so I now need help.
 

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Premium Member
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2,714 Posts
Hey smart people and engineery types - how do I accurately (to 0.01mm anyway) measure the nipple bed thickness on a rim?

Ok go!

Hmmm, how about a spacer of known length that will go down through the rim bed hole? Now measure (with vernier caliper) from spacer top to rim inner circumference and deduct the spacer length?

I already figured out how to measure the brake track thickness. That maxed me out so I now need help.
I dont think the spacer approach will give the accuracy of +/- 0.01mm you are after because of irreguralities at the contact points. Maybe if you use two nipples, one on each side, and tighten them down to improve on the accuracy? still though kinda crude for 0.01mm accuracy.

Edit to add: the valve hole may give you more space to work with.
 

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A wheelist
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11,324 Posts
Discussion Starter · #6 ·
I dont think the spacer approach will give the accuracy of +/- 0.01mm you are after because of irreguralities at the contact points. Maybe if you use two nipples, one on each side, and tighten them down to improve on the accuracy? still though kinda crude for 0.01mm accuracy.
Good thoughts on the accuracy Griz. I did the measurement 3-4 times and got different answers 3 out of the 4 times so I kinda averaged. And with nipple bed thicknesses hovering around 2mm, this might not be a great idea.

I had the same irregularities measuring the brake track thickness (as I used a 3/8" long spacer there) and averaged a bunch of readings.
 

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Premium Member
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you know that buying a micrometer will solve your predicament and Im sure you need a micrometer :idea:
 

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Huge in Japan
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456 Posts
.01 mm accuracy (accuracy is not the same as resolution) you will need better than a digital caliper (that is not a Vernier caliper BTW, this is a peeve of mine but I design gages and program measuring equipment for a living so that's another discussion). If you use hard gaging you'll need to make sure you are not measuring over a burr or other type of raised surface. Also form will have an effect as I presume the nipple bed is not sufficiently flat. My totally impractical suggestion for your purposes but well suited for your desire would be an ultrasonic thickness tester.
 

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A wheelist
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11,324 Posts
Discussion Starter · #12 ·
Ok so no one has asked. Why do you need to measure the nipple bed thickness to 0.01mm?
Good question! I preview rims occasionally and everyone tries to get one up on the competition. When they come with a lighter weight, I want to know where they saved the weight. Will it affect rim life?

A thinner (or narrower!) brake track and thinner nipple bed have the potential to save weight at the expense of longevity.

no one has asked
Some of the responders would already know why.
 

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A wheelist
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11,324 Posts
Discussion Starter · #15 ·
Interesting. How can one test how it would affect rim life? I would imagine way too many variables to control for.
Oh for sure I can't do exhaustive experiments that take in all the factors like rim material etcetera. But the average guy can attempt to draw some conclusion - even if it's not, and never will be, the full story. I doubt anyone outside of the rim makers and designers has the capability to do definitive tests.
 

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Cranky Old Bastard
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Mike, could you hold a piece of metal against the nipple hole on the inside of the rim and touch it with the depth gauge on your calipers (from the outside of the rim)?
Then move it over a little and take the measurement of the rim right next to the hole.

I don't know if I explained it well and I don't have an unlaced rim to take a pic.
 

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Cranky Old Bastard
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2,337 Posts
Wait, you're just trying to measure the rim thickness at the spoke hole, right?

Get a rod (with polished/perfectly flat end) just a little bigger than the spoke hole and hold it tight against said spoke hole (from outside of rim). Use depth gauge on calipers to measure thickness (with caliper on inside of rim).
 
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