How to lock a nut tight on a threaded rod ?

[murrmacParticipant @murrmac]

I hadn't thought about soft soldering … would that withstand the same torque as using Loctite? For some reason I didn't think that steel could be soldered satisfactorily by soft soldering , obviously I was wrong.

I have ordered a bottle of Loctite 638, as per Michael Gilligan's suggestion so we will see how that goes. Pricy stuff, innit?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by murrmac on 21/09/2014 10:14:56:

I hadn't thought about soft soldering … would that withstand the same torque as using Loctite? For some reason I didn't think that steel could be soldered satisfactorily by soft soldering , obviously I was wrong.

I have ordered a bottle of Loctite 638, as per Michael Gilligan's suggestion so we will see how that goes. Pricy stuff, innit?

.

• would that withstand the same torque as using Loctite? — No [assuming 638]
• Loctite 638 … Pricy stuff, innit? — 'fraid so, but it's very effective, and you don't use much.

MichaelG.

[Keith HaleParticipant @keithhale68713]

Shear strength loctite 638 25N per sq mm

Shear strength tin lead solder 37N per sq mm

Shear strength silver tin 41N per sq mm

Keith

[Michael GilliganParticipant @michaelgilligan61133]

Keith,

I stand corrected

… but, of course, 638 is very easy to use.

MichaelG.

[murrmacParticipant @murrmac]

Interesting stuff … I wouldn't have the necessary equipment to do the soldering anyway, so Loctite it will be.

My intent is to cut a thread an inch onto the end of the 5mm rod , then fit on an M5 nut and tighten it up real good so that it is hard up against the unthreaded part of the rod. I then put on the connector nut and tighten that so that it locks hard against the first nut.

My instinct is that doing this (in conjunction with the Loctite of course) will give the strongest possible bond using this method, but maybe using the first nut is superfluous, and it will be just as strong if I tighten the connector nut hard up to the unthreaded shoulder of the rod ?

While we are at it, (and purely out of interest), would I be correct in thinking that if this assembly were to be soldered , either soft or hard, that one would not tighten the nut hard up, but just thread it on loosely and let the solder fill the gaps?

[Jon GibbsParticipant @jongibbs59756]

Interesting figures – I think we can be certain that either's strong enough though…

Rough calculation of surface area for an M5 x 0.8 thread through a 10 mm long connector nut would be in excess of 150 sq mm (pi x diameter x length not including the additional s.a. of the thread). So whether it's 25 N per sq mm (>3750 N) or 37 N per sq mm (>5550 N) I think we can be sure the threaded rod will break before the bond.

Jon

 

Edited By Jon Gibbs on 22/09/2014 11:26:02

[Michael GilliganParticipant @michaelgilligan61133]

Just for ease of reference; this page has links to the data for both the "old" and "new" formulations of Loctite 638.

MichaelG.

.

Edit: and I have just found this useful table, which includes the range of shear strengths for vaious mixes of Tin-Lead.

Edited By Michael Gilligan on 22/09/2014 11:40:58

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