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Bolt assessment help

Bolt assessment help

Bolt assessment help

Apologies if this is a daft question but I am new to this forum and new to the fastening field. I have a shaft collar with radially mounted bolts. The only info I see on bolting patterns for assessment is when mounted longitudinally. The only load here is a small tensile force and moment no torsion. The fit between collar and shaft is a machined fit so the bolts would not experience the moment only the resultant shear. Do I just look at this simply as simple bolt acting in shear? I was hoping someone could help to confirm if im thinking this through correctly or not. Thanks

RE: Bolt assessment help

Hi TomW88

Can you post a picture or sketch showing the set up you have?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Bolt assessment help

It’s hard to picture your arrangement. Try posting a figure.

RE: Bolt assessment help


This sounds like you have set screws. The end of the screw is digging into your shaft, creating an indentation, i.e. stressing your shaft or your screws above their yield point. As you apply torque, the indentation will enlarge and your collar will come loose. I hate set screws.


RE: Bolt assessment help

What is this "machined fit" between collar and shaft that is capable of absorbing all radial loads ? What might those radial loads be ?

The good SHCS (Socket Head Cap Screw) manufacturers list permissible loads/holding power for their SH Set screws.
Say 1000 lbs ± XXX depending on the size of the set screw.

Like Drawoh, if the loads are the slightest bit cyclic I too have learned to hate and distrust set screws

RE: Bolt assessment help

same, I am not a big fan of set screws,

RE: Bolt assessment help

OP has not been back for about a week, since March 23. So the last response he could have read was a picture request from desertfox.

RE: Bolt assessment help

Apologies everyone, I had an internet issue. I thought switching to Fibre would be a quick switch over but it turns out not.
Thank you for everyone that replied though and my apologies for not giving better info.

Connection is shown in the quick sketch attached. For a little more info that shaft collar eventually connects to a hose end which will angle down under its own weight for a couple of metres and cause a moment on this section.
The main connection bolts/structure were assessed but not the inset socket head cap screws you can see.
There is no tension (Original post incorrect) and no torsion present only the moment from the hose.

Connection has been given a close clearance (f7/H8) fit so there would be between 0.17 – 0.05mm clearance

Thanks and again my apologies for not responding sooner.

RE: Bolt assessment help

Hose = water etc? So there are seals in there somewhere between "collar and shaft"??
Are the setscrews being asked to maintain the collar in a precise axial location to make an o-ring or gasket compress and seal in a face-seal arrangement?
Or, is there an or-ing that is in a groove in the shaft or collar, so an errant setscrew could scratch an axial groove across the sealing surface when the hose/collar is installed or removed?

As a starting point to provide a feel for the scale and magnitude of this arrangment"
- What size are the setscrews.
- How much will a "couple of meters" weigh?
- What is the potential that the hose may deliver a healthy tug (tension or bending) on this fixture once in a while?

RE: Bolt assessment help

If there is flowing fluid and a direction change then there is tension - somewhere.

There is a whole universe of already engineering hose couplings. None of them work for your undefined application?

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