Threading problem?

[cessna]

Hi, I am building a cam for my engine, the lobes are set screwed to the shaft, I drilled and tapped the lobes with a 5-40 tap. A 5-40 bolt screws in fine but the set screws I have do not, appears they are coarser thread. My question is are there different pitches of threads on set screws ?
Terry

 

[Swifty]

The short answer is no, so long as they are 5-40 set screws. 5 is reference to the diameter and 40 is the threads per inch. The set screws must be a different thread, if you hold the bolt thread against the set screw, do they match. The set screws may be 5-44.

Paul.

 

[cessna]

Thanks for the reply Paul, will have to look closer.
Terry