Bolt Thread Measure
Discussion
Is there such a thing?
I'm in the middle of re-building something that has been completely bastardised at some point, to the degree where all the nuts and bolts etc have different heads.
Im trying to go through and replace each one, one at a time but this would be greatly assisted if I could take out a bolt and find out what thread was on it - rather than having to take a box full of bolts out the shop each time.
I could then order over the t'internet if I knew what I was after.
Anyone know of a handy tool for this?
I'm in the middle of re-building something that has been completely bastardised at some point, to the degree where all the nuts and bolts etc have different heads.
Im trying to go through and replace each one, one at a time but this would be greatly assisted if I could take out a bolt and find out what thread was on it - rather than having to take a box full of bolts out the shop each time.
I could then order over the t'internet if I knew what I was after.
Anyone know of a handy tool for this?
A ruler, or vernier caliper can do it. The distance between the tips of the threads is the pitch. So 1.25 thread pitch is 1.25mm. The thread pitches are normally one of three possible pitches for each diameter bolt, coarse, fine and standard. You will very rarely see coarse, occasionally fine, and mostly standard.
For example (from memory) M8 (8mm metric bolt) standard pitch is 1.25mm from tip to tip.
You can buy a thread gauge, but I've never really found the need for one to be honest. I tend to use my vernier or a ruler.
For example (from memory) M8 (8mm metric bolt) standard pitch is 1.25mm from tip to tip.
You can buy a thread gauge, but I've never really found the need for one to be honest. I tend to use my vernier or a ruler.
Depends on what it was when it was made and how bastardised it's been. A UK classic can end up with a huge array of random fasteners.
I've had to rebuild machinery that was designed and purchased in the US using imperial fasteners and then commissioned in the UK using metric ones. In the smaller and more obscure sizes it can be tricky to tell exactly what thread you're dealing with. Back then I had a labelled example of each thread, and with a bit of measuring it was easy enough to tell what you had.
I work exclusively in metric now, which is much easier (even with comedy fine pitches used occasionally in high load applications).
I've even built up a stock of JIS spec bolts to avoid the annoying 13mm AF heads on BS fasteners when fixing Japanese cars. When I bought my Elise I had to buy a pair of 13mm spanners...
I've had to rebuild machinery that was designed and purchased in the US using imperial fasteners and then commissioned in the UK using metric ones. In the smaller and more obscure sizes it can be tricky to tell exactly what thread you're dealing with. Back then I had a labelled example of each thread, and with a bit of measuring it was easy enough to tell what you had.
I work exclusively in metric now, which is much easier (even with comedy fine pitches used occasionally in high load applications).
I've even built up a stock of JIS spec bolts to avoid the annoying 13mm AF heads on BS fasteners when fixing Japanese cars. When I bought my Elise I had to buy a pair of 13mm spanners...
doogz said:
What's annoying about 13mm AF M8 bolts? What am I missing?
It's annoying if you've mostly had Japanese cars with 12mm heads and someone has replaced a handful of them with BS spec 13mm ones on a job that requires you to crawl on your shoulder blades over a gravel drive to get from under the car to go get the 13mm socket 
There is nothing wrong with them, unless they appear where you aren't expecting them.
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