Cummins 4BT & Diesel Conversions Forums banner
1 - 5 of 5 Posts

·
Registered
Joined
·
812 Posts
Based on what assumptions?
Thread fit?
Material strength?
Fastneer strength?
Fastener torque?
Coarse threads or fine?
Mismatching elastic modulus of the bolt and socket?
What level of friction between threads (any lubrication)?
Linear elastic thread behaviour or yielding?

Three threads in 6061 aluminium can be stripped out very easily. Try it if you don't believe me.
Three diameters for reusable aluminium threads is a safe level for the worst case. It holds after bolts have been removed and refit many times.

In contrast one of the designers at my last job had M6 cap screws threading into 4mm of mild steel. Several of them stripped out during assembly of the brand new machine.
Dougal;
Is 3x diameter a engineering standard ? Is it for Aluminum and steel or both ? Not being an engineer, I am always trying to learn more.
So for a 1/2" bolt your suggesting the tapped hole be 1.5" deep ?

Thanks
Paul
 

·
Registered
Joined
·
812 Posts
Paul (in NY)-
Is that the vehicle you are swapping the 4bt into, or did you just lay your hydraulic press down horizontally and mount the engine and wheels to it? ;) :D
I have got to hand it to you, I am impressed! I am always over engineering things, but that has to be one of the best examples of over engineering I have seen in a long time.:beer:
Were you in the Army corp of Engineers too.
Just have to figure a way to mount a windshield. HA HA ! Never in the Army Corp of Engineers. I always try to build super kill, then to be sure its dead, shoot it and then run over it ha ha. But Seriously, I once saw a Engine stand topple over with a 350 Dressed Chev engine. No one was hurt !. This stand wont topple, but equally as good is that any engine can be test run for as long as you want. When it finally goes in the truck, your KNOW your good to go.

Paul

Paul
 

·
Registered
Joined
·
812 Posts
Not a standard, just a "best practice" rule. 3 thread diameters deep in aluminium and 1.5 diameters deep in steel.

Of course it's for non-replacable threads. Most nuts only contain 3/4-1 diameter worth of thread, but they're harder than mild steel and usually easily replacable.

If you're restricted to less thread depth than that, you can improve things by helicoiling the thread from the start. The Kuka industrial robots I've worked with have this done to them to create a stronger thread in light aluminium parts.
Thank You
Paul
 
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top