Threaded insert spacing

[Ezequiel1982]

Dear All,

Here is my case.. I have a camera housing (rectangular box made of steel) bolted to a bigger structure. So far I am using M12 DIN912 bolts made of INCONEL 712 and to increase the strength of the 'female' thread I'm using M18 (external thread) inserts. This is a tapped bolted connection.

My question is, is the bolt spacing 3 x bolt diameter or 3 x insert diameter (M18)? It is not very clear to me so I would appreciate your help!

Thanks a lot!
Ezequiel

 

[JohnRBaker]

I would go with 3 x the insert diameter since the issue is the distance between the O.D. of the threaded holes, not necessarily the distance between the sides of the bolts.

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[mfgenggear]

Ezequiel1982
a sketch with dimensions would be much clearer

 

[SWComposites]

Must be one heavy camera if you need to use very expensive inconel bolts.
Yes, add a sketch.

 

[Ezequiel1982]

Dear All,

Thanks for your comments! It is not a heavy camera but it is subjected to very high electromagnetic forces. This way I am using INCONEL. Furthermore, due to lack of space I can't increase the size of the bolts.

As far as I could read the distance 3 x bolt diameter is to avoid bolt's pressure cone interfere with each other because if that happens then the stresses will be too high and the component may fail. If it is true, then the driven dimension is the bolt head diameter and not the insert diameter.

What do you think?

cheers!
Ezequiel

 

[EdStainless]

No, the load is being transferred through the inserts, their OD is the governing dimension.
Could you get away with 2.5x? Likely, but you do risk causing distortion of the mating face.
If there is so much EMF involved why is the box steel?
Can you get hardware in Nitronic 50?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[drawoh]

Ezequiel1982,

Why so many bolts? Are you trying to seal the thing?

--
JHG