Anti Rotation in Nut with low torque to start with

[cps.13]

Hi,

i'm hoping to get a bit of assistance with stopping a nut from coming un-done if possible.

I have an application using a load cell which is being inserted into metal rod, and then pulled under tension. The load cell is inserted into a hole drilled in the rod and screwed in at the bottom end (loosely). The load cell has an external thread on the other end, which then has a nut placed on it and screwed down 'tight'.

my problem is that I cannot apply large amounts of torque to the load cell as it starts changing the output. But I also need it tight enough so it cannot come undone.

At the moment I have a nyloc nut on the thread (m20x1.5), I have tried using Nordlock washers but couldn't tighten the load cell up enough to get them to work.

the problem is I cannot measure how tight I am doing them up at the moment as I do not have a method of doing so.

But does anybody know of a good method of stopping a nut from coming undone when it isn't torqued up high to start with?

I cannot post drawings/images as its commercially sensitive.

thanks,

 

[Nidum]

Loctite Threadlock

 

[cps.13]

sorry - should have said... it needs to be removable so I cannot "weld" it in using loctite.

 

[Nidum]

http://www.loctite.co.uk/loctite-4087.htm?nodeid=8802623422465

http://tds.loctite.com/tds5/docs/222-EN.PDF

 

[Nidum]

Or make a special nut with side screw or side clamp locking .

 

[jack action]

Looks like a job for a jam nut.

 

[Tom.G]

Or a job for a Castle nut with either a cotter pin or safety wire thru it.

https://www.google.com/?gws_rd=ssl#q=castle+nut

https://www.google.com/?gws_rd=ssl#q=castle+nut+safety+wire

 

[Baluncore]

Consider a nut that has a cam on either side, operated by one lever.
Run the nut down the thread until it first contacts, then swing the lever over to apply the axial force.
There will be very little wear on the thread since there is no pressure while thread turns.

 

[Averagesupernova]

Not all Loctite is non removable.

 

[rbelli1]

This? It is something like Baluncore described.
http://www.rallydesign.co.uk/produc...ts_id=16635&osCsid=9ljltcrksuana1sqggicgl47u3

BoB

 

[Baluncore]

This? It is something like Baluncore described.

I do not recommend those lockable nuts.
Attached is a picture of a similar concept to my suggestion. But make it an over-centre cam that is big enough to contain the 20mm nut.