Stainless or hight tensile mount bolts?

[Alfian]

I am eventually getting round to mounting a second dovetail clamp onto my Giro. It has occurred to me that we put a lot of faith in two M6 bolts to hold our optical treasures firmly in place. Do I therefore use stainless steel bolts, which is what I think are currently on the mount or high tensile bolts? Has anyone ever had breakage of  saddle mount bolts?

[Alien 13]

I would go for A4 stainless..

Alan

[laser_jock99]

35 minutes ago, Alien 13 said:

I would go for A4 stainless..

Alan

It's a bit more complicated than that- high grade carbon-steel bolts are stronger.

[Bizibilder]

M6 bolts have a safe load of around 200kg.  Two might be overdoing it!!!  Seriously though - the bolt sizes we use, generally M6 to m12, are more than adequate for the loads we subject them to with Astro gear.

Stainless won't rust but are expensive.  Another issue if you live near the sea is that stainless will corrode in salt spray quite rapidly.

[Alien 13]

5 minutes ago, laser_jock99 said:

It's a bit more complicated than that- high grade carbon-steel bolts are stronger.

I agree but we still used A4 stainless in the Aerospace industry even when shock/vibration testing, never had one break, if using carbon steel bolts they need protection from rust.

Alan

[laser_jock99]

Must admit I use stainless - on the basis that we astronomers are nowhere need the max load stress, they don't rust, and we don't use anything other than stainless at work.....

[Alfian]

It's looking like I'm pretty safe with stainless then.

[nightfisher]

Stainless will be spot on, some very good sellers on ebay, i tend to get plenty of fixings on there

[Bukko]

I have worked around the Chemical Industry for decades and the sites are all close to the sea...

For pipes, we always use high tensile studs and I agree, they do rust. But while they look horrible with a coaitng of rust on them, they do not fail unless you get some "nasties" on them.

But as said above, the loadings we apply to our equipment really does not need high tensile stuff.

To me it is a matter of it looking nice, rather than the strength. If you go for high tensile fixings, though, put a little copper grease on the threads, so you can undo them later..

Gordon

[Alfian]

18 hours ago, Bizibilder said:

M6 bolts have a safe load of around 200kg

I think this will be sufficient to hang about 4.5 Kg from so no sleepless nights. Thanks everyone.

[Alan White]

My ADM clamp was supplied with M6 stainless hex screws, so if its good enough for ADM, it's good enough for me.
 

[Davey-T]

Never had a stainless steel bolt fail and we're usually only screwing them into aluminium, high tensile bolts are designed to be done up to a specified torque, which may exceed the capabilities of aluminium to withstand, and then left alone, not constantly being undone and retightened.

Dave