Moses Bolt Torque?

[grigorib]

My practice to not overtightening the bolts are:
- use my left hand to tighten
- use screwdriver-base T-30 to avoid temptation of using that long lever on the key

Here goes a joke for this thread
Do you know what a redneck torque wrench is? Tightening until you strip the thread and then loosen it by quarter turn

[Robsw6]

I use one of these (https://www.prestacycle.com/wp-content/ ... orque7.jpg @ 7nm and usually then feel whether it feels tight enough - these keys are designed for tightening carbon bike stems, so I figured they"should" be ok - ie tightening enough/without overtightening & causing damage

[Onda]

I posted an official table in another post some months ago, see link below.
The maximum torque is a function of the type of thread, the diameter of the thread and the material the screw is made of (tensile strength).
For stainless steel screws in M6 / tensile class 6.8 the maximum torque is 7.7 Nm (newton-meter). Which really is not much. You can very easily over-tighten such a little screw with a normal torx-key. So be careful.
https://www.anzugsmoment.de/anzugsmoment/ (maximum torque according to German / EU standard)

It also depends on the coefficient of friction between the threads, and the head and the fuselage, and also the diameter of the head.

Yes.
The standard values are valid for dry (non lubricated) thread.
If you lubricate, then the allowable torque is much lower, actually non-specifiable.
Aluminium shouldn´t impact the allowable torque as long as the thread length is big enough. Which should be the case at least for my Moses fuselage.

All of which lead us to the conclusion: Really don´t use too much force

[wavy navy]

The first of 2 mast-to-fuselage-screws untightens itself every session, no matter how tight I screwed it. This never seemed to be a problem to me. The whole connection seems to be very stiff.

[Foil]

The first of 2 mast-to-fuselage-screws untightens itself every session, no matter how tight I screwed it. This never seemed to be a problem to me. The whole connection seems to be very stiff.

Being here on Flag beach for the next 6 months and foiling nearly every day has given me time to try to find the point where this self loosening, "magic" front mast bolt to fuse phenomenon becomes a problem,
Fact is it's not a big problem, but if you are a worrying type person then yes! It can drive you to distraction, and at times when hitting turbulent water I also think "is that my fuse falling off my mast"?
First of all,either tightining down slowly and steadily, a bit on each bolt front then back multiple times verses nipping up the bolts lightly then rocking back and forth on the wings to press the surfaces together works just the same, no noticeable difference,
Using a washer, be it a flat or spring type makes a big difference verses no washer, but the type of washer makes no difference,
If you tighten up too hard you hear a nasty creak sound, and this sounds so wrong, and is unnecessary as it makes little difference, and the front bolt still loosens, so I definitely avoid the point of the creak sound, I now use 2 fingers and 1 thumb on my 15cm torx head bar, yesterday I used minimal force, just 1 finger and 1thumb, and all was just fine, boosting as normal on my 101 mast and hard deep carves to really give the joint a bit of testing, however the front bolt was that loose after the session I could spin it out with just 2 finger tips, the rear bolt was not loose and needed the key to remove it,
But as always I had to knock the fuse hard with my hand to break the friction fit of the mast on the fuse,

But going forward I will go back to 2 finger and 1thumb pressure to tighten in future, as a free spinning bolt is just too scary to see after a session.
The 6mm bolts are stainless steel into a stainless steel fixing, so grease is not needed, and better avoided as it attracts sand, unless of course you rarely dismantle the 2 parts,

[purdyd]

The 6mm bolts are stainless steel into a stainless steel fixing, so grease is not needed, and better avoided as it attracts sand, unless of course you rarely dismantle the 2 parts,

'

Stainless to stainless threads can gall. Especially if loosened and tightened repeatedly. This means there is a lot of friction and that means those recommended torque setting don’t apply. And the amount of preload is going to be less than you would like.

Creaking is a pretty good sign you have a lot of friction.it a bolt is getting loose either the joint is compressing or the preload on The bolts is not sufficient to prevent movement and the bolt rotates.

it would be interesting to mark the bolt and observe if it rotated.

[PrfctChaos]

The first of 2 mast-to-fuselage-screws untightens itself every session, no matter how tight I screwed it. This never seemed to be a problem to me. The whole connection seems to be very stiff.

If you tighten up too hard you hear a nasty creak sound, and this sounds so wrong

The 6mm bolts are stainless steel into a stainless steel fixing, so grease is not needed, and better avoided as it attracts sand, unless of course you rarely dismantle the 2 parts,

Would highly recommend using some lube, such as Tefgel (Or another S/S type anti-seize). That sound is the Stainless welding together at little points and then breaking loose. One day it will be permanently stuck.

[Peter_Frank]

Does anyone know WHY it becomes loose?

There must be many two screw connections out there, but I have only heard it as an issue on the Moses.

Could be good to know from a design wise point.

Peter

[grigorib]

The first of 2 mast-to-fuselage-screws untightens itself every session, no matter how tight I screwed it. This never seemed to be a problem to me. The whole connection seems to be very stiff.

I believe cone connection settles in a bit after a first and a second sessions following the assemble. Then bolt doesn’t loose up if you don’t disassemble the foil

[Wazza Foil]

Does anyone know WHY it becomes loose?

There must be many two screw connections out there, but I have only heard it as an issue on the Moses.

Could be good to know from a design wise point.

Peter

I have had a Moses quiver for a couple of years with frequent use and no issues.