DRILLED & TAPPED HOLE DEPTHS

[STUARTF]

Now now boys! Calm down!


This topic seems to have gone off track a little bit.


I liked the comment about using revolves instead of holes.


Would that effect the hole chart tool?

 

[dr_gallup]

Jrobi,


I would envite you to come to our company and do a distructive burst test on a standard size cut thread at over 5,500 psi. If you go by the book like your saying it will not make 4,000 psi. If you use form threads at three to four times diameter it will make the pressure. Your text book data will pull the threads out of the casting. Threads are an art in there own way. I have done a lot of work with threads to get the maximum strength. Being that we make most of the hydraulic elevator valves in the US I don't think that you would want threads to pull out of the valve with ten people on the fifth floor in the car and drop into the pit? Textbook does not always work.

Right on. Textbook values typically are based on using steel in steel. Many materials behave quite differently (non-linearly) than steel. Since you are tapping castings I assume the material is either cast iron or aluminum. I don't have experience with aluminum but I know from experience that threads in cast iron need a lot more than 2x diameter engagement for maximun strength. Blindly relying on textbook solutions for safety critical applications is always dangerous. A single test is worth a thousand expert opinions.

 

[kschauer]

dr_gallup,



I'm with you most of the way. The text states that it is for
simular materials. Working with cast Aluminum myself, I can
assure you that the Aluminum threads start to see Slip way before a
Class 9.8 bolt goes into the plastic stage. Rules of thumb are
great but people need to relay on thier Engineering skills and thinking
form time to time.