Sliding Bolt Grip Clearance

[DougTheThug]

Hi all,

I'm working on two plates that will be bolted together by a 3/4" bolt. The top plate has a slotted counterbore so that it can slide against the other (this is for thermal expansion purposes). What clearance should the grip slot have? Picture attached. Currently I have a clearance of 1/8".

 

[3DDave]

Overall this is really a stress problem, not a dimensional problem. Even 0.000000001 inches is enough clearance to allow sliding. Sliding puts a bending moment on the bolt. This may not be desirable.

What is typically used is to put a sleeve on the bolt to ensure the bolt can be tightened to around 80% of its full elastic limit so that it won't come loose. Just ensure the gap that remains is OK over the temperature excursion.

 

[drawoh]

DougTheThug,

What is your concern? If the bolt must fit through, the hole must be larger. 1/8" does it. If you have multiple bolts, the hole clearance must account for positional error in all the holes.

 

[DougTheThug]

DougTheThug,

What is your concern? If the bolt must fit through, the hole must be larger. 1/8" does it. If you have multiple bolts, the hole clearance must account for positional error in all the holes.

That makes sense. I wasn't sure if the clearance was too much or too little and wanted to know if there was a standard table or equations to determine what was necessary. Although, it makes more sense just to consider the tolerance of the machine that will be making it so that all bolts will have sufficient space. Thanks.

 

[drawoh]

That makes sense. I wasn't sure if the clearance was too much or too little and wanted to know if there was a standard table or equations to determine what was necessary. Although, it makes more sense just to consider the tolerance of the machine that will be making it so that all bolts will have sufficient space. Thanks.

Ask the guy who is going to make the holes.