How much Torque

[Etherealicer]

So, I saw the latest products from Topeak (release in 2016), which are bit adapters for 5mm Allen keys (any MT with a 5mm Allen key around?). They are rated 4, 5 and 6 Nm. Sadly, I have no idea if this is a lot or if this is too little to bother, anyone got some insight about the torque on small bit wrenches?

PS: the Tools are really drool worthy:
There is the adapter set Nano TorqBox 6Nm


And the Nano TorqBar 6Nm

[sLaughterMed]

Well assuming Nm means Newton meters, its not a whole lot of force, but these are bits. You shouldn't really be putting a ton of torque on them anyhow. They arent meant to go into a drill chuck. However the fact that this company yook the time to actually test and rate these bits means they probably can stand up to a fair bit more force than typical bits.

If you can follow basic physics, heres some fun for you!

Newtons are a measure of Force.

Force=Mass X Acceleration

Gravity's Acceleration=9.8m/s^2

Nm is a measure of Torque. T=Force X Distance from pivot
So in this case, T=4, 5 or 6 Nm
Lets say you use a 15cm (.15 meters, or just shy of 6 inches) long bit ratchet to turn a screw. And we pick the bit rated for 4 Nm to turn this screw. How much force can we safely apply before exceeding this bits rated performance?

If we rearrange our two equations, we find that
Force=Torque/Distance

 So our maximum force with the 4Nm bit is 26.667 Newtons. With the 5Nm bit its 33.33 Newtons, and the 6Nm bit is 40 Newtons.

That's great and all, but what does that mean? Let's find out!

A LM new Wave is 8.5 oz, or 241grams (0.24kg) so, if we drop our Wave from 1 meter (about 3.3 feet), the Wave will hit the ground with about 2.4 Newtons of force.

So now lets imagine your screw is on a vertical wall, and you hold your bit rachet perfectly horizontal. If we want the maximum force on our 4Nm bits, we can drop about 10 Leatherman Waves from 1 meter onto the end of the rachet at the same time.

Id say thats a fair amount of force for a screwdriver bit to take all at once. Not bad.

Besides, those look fantastic. I say if theres a need, get them!

[Etherealicer]

Yes they do look great

Thanks for the explanation. I think they are limited so you do not over tighten screws that go into a carbon frame and destroy the frame. I just had no idea if that is much or not. So a force equivalent of 2.6-4 kg (Thanks for doing the math, it didn't even occur to me I could calculate that ), not all that much but probably enough for all my stuff.

[sLaughterMed]

Yes they do look great

Thanks for the explanation. I think they are limited so you do not over tighten screws that go into a carbon frame and destroy the frame. I just had no idea if that is much or not. So a force equivalent of 2.6-4 kg (Thanks for doing the math, it didn't even occur to me I could calculate that ), not all that much but probably enough for all my stuff.

No sweat. It was actually really fun, I love that kind of stuff. In a way you did me a favor, and reminded me why I am studying engineering...

The limited torque to prevent damage to carbon frames is aa very plausible explanation, although I know nothing of bikes, so past the math, your on your own.

Maybe the best solution is just to drop a bundle of Waves onto the handle so you always use the correct force...

[smiller43147]

Torque doesn't really translate into force. However, Nm (Newton*meter) does equate to lb*ft (pound*feet).  And 6 Nm is only 4.4 lb*ft.  I don't know what a typical bit can handle, but 4.4 lb*ft isn't a whole lot of torque.

For comparison, auto lug nuts take 75 - 100 lb*ft to tighten.

[sLaughterMed]

Torque doesn't really translate into force. However, Nm (Newton*meter) does equate to lb*ft (pound*feet).  And 6 Nm is only 4.4 lb*ft.  I don't know what a typical bit can handle, but 4.4 lb*ft isn't a whole lot of torque.

For comparison, auto lug nuts take 75 - 100 lb*ft to tighten.

Not directly, but if we put the maximum torque into a problem with a lever, we can find how much force is applied over a specified distance.

Keep in mind these bits are for bike frames. The forces involved are way smaller than those in a car. Sure, 4.4lb*ft isn't much, but its more torque than hand tightening would produce

[sLaughterMed]

I just looked at the product page for the first time

This thing is way cooler than i thought. It will only apply up to the rated torque. So if you exceed the maximum torque, this bit adapter ONLY APPLIES 6Nm of torque! It's a torque limiter!

I thought the bits would fail after 6Nm was applied. Its not the bits that are rated, its the adapter, which has aa mechanisim that applies, at most, 6Nm of torque. I suppose high end bikes have specifications on how tight their screws and bolts have to be, and this tool would allow you to get the perfect torque every time.

[hiraethus]

It's not a torque limiter, just a (rough) indicator of when you've reached the preset torque. You can carry on tightening the screw as much as you like, even after it's clicked to warn you to stop.

Lots of bikes now come with lightweight aluminium and carbon components, and a lot of them are clamped together with M5 screws. 4-6 Nm seems to be a reasonable torque for there's parts. I've got a torque wrench for working in my bikes, but rarely use it if I'm honest. I tend to go by feel and experience.

[anditsgone]

I estimate that 6nm is about the same as when you tighten a screw by hand.
You can not put More torque on a small torx head because it will bend or break.
I also guess they estimate a low number to cover them selves. In reality they will probably go to 10.

[Etherealicer]

Thanks guys... that sheds some light

[shibafu]

From a couple of motorcycle manuals I have to hand, it looks like 5 to 6 Nm is a usual torque range for a 5mm hex bolt.

[Sea Monster]

So now lets imagine your screw is on a vertical wall, and you hold your bit rachet perfectly horizontal. If we want the maximum force on our 4Nm bits, we can drop about 10 Leatherman Waves from 1 meter onto the end of the rachet at the same time.

Failing access to 10 Leatherman Waves, you could buy a Topeak Torqbox, and it'll do the math for you.


I've got an adjustable 1/4" socket torque driver, which I use basically never.
I suppose low Nm settings might be more useful to cyclists with delicate parts, but I come from the "turn it as far as you can, then put a cheater bar on it and turn it another 90 deg" school of assembly.


But cool toys are cool toys, and one day someone will need to tighten a bolt to an exact torque, and BAM, you'll be waiting, ready to go, all your life leading up to that point, and it will be money well spent.

[Etherealicer]

So now lets imagine your screw is on a vertical wall, and you hold your bit rachet perfectly horizontal. If we want the maximum force on our 4Nm bits, we can drop about 10 Leatherman Waves from 1 meter onto the end of the rachet at the same time.

Failing access to 10 Leatherman Waves, you could buy a Topeak Torqbox, and it'll do the math for you.


I've got an adjustable 1/4" socket torque driver, which I use basically never.
I suppose low Nm settings might be more useful to cyclists with delicate parts, but I come from the "turn it as far as you can, then put a cheater bar on it and turn it another 90 deg" school of assembly.


But cool toys are cool toys, and one day someone will need to tighten a bolt to an exact torque, and BAM, you'll be waiting, ready to go, all your life leading up to that point, and it will be money well spent.

They are very pretty, I realized though that I have the same without torque limitation in the Victorinox/PB Swisstool bike-kit.

Although there are plenty of applications where limiting torque makes sense. I have ruined the thread on a PC case where the screw goes into the aluminum frame. Not a tragedy but I was annoyed nevertheless.