Turn of the Bolt Methods Implementation

[Froggy00]

Hello,
I have an application that required a preload of 50% of the proof load on a M24 x 70 to 120 long. The bolt goes thru a clearance hole and threaded on to a tapped hole. The space restriction does not allow the use of a torque wrench. I planned to use the "turn of the nut/bolt" method. The connection is pretty rigid and I calculated I need a rotation of 15-30 degrees. The problem I have is implementation. I can see this method working for "half turn" or "full turn" but 15-30 degrees seems rather hard to measure.


Do you have any recommendations or past experiences that you can share with me? Any help would be great! Thank you.

Regards,

Allan Lee 

 

[MintJulep]

Mark the mid-point location of a screw flat on the part with the clear hole. Turn until the next point of the screw head gets to that mark. That's 30 degrees.

 

[evelrod]

Make it easy on yourself. Do it like the ironworkers have been doing it for a hundred years, by counting the "flats".
In actual practice, that is as close as you are likely to get. You will need to set some parameters to determine exactly what "snug tight" means before you start. Some guys are tougher than others and, therefore, snug takes on a new meaning. If your work is super critical, set up a Skidmore and practice before you do the real thing.

Rod

 

[QAFitz]

I always thought that if a wrench could be put on
that wrench could be used as an extension for a
torque wrench.
- The wrench goes on the nut/bolt you want
to tighten;
- the torque wrench goes on the other
end of the wrench;
- the mechanical advantage is calculated and
applied to the torque requirement;
- the resulting torque is applied.

 

[Froggy00]

Thank you everyone for your input!

Using the screw head is a good idea but I have a socket head cap screw. The flat is inside the socket.

Do you know of any adapter/extension that can join an Allen Key with a torque wrench?

Snug tight is another tricky questions, as everyone's snug tight is different.

Allan Lee

 

[unclesyd]

You might want to use a device like this with proper supervision. The only problem I see would be that the head on SHCS might have bearing area problem.

http://www.turnasure.com/direct-tension-indicator.shtml

Here is synopsis of the bolt tensioning requirements.

http://www.boltcouncil.org/educ4.htm

 

[BillPSU]

Froggy00
Sure they make socketed allen drivers.

 

[Kenneth]

Do you know of any adapter/extension that can join an Allen Key with a torque wrench?

http://buy1.snapon.com/catalog/item.asp?item_ID=818&group_ID=275