3-piece DE razors : their weakest point

Posting some pics ( 'cause one pic is a thousand words ) to get the conversation 
started . What you do understand from these pics ? What do you think ? Where exactly is the weakest point on a three piece double edge razor ? 

Posting some pics ( 'cause one pic is a thousand words ) to get the conversation 
started . What you do understand from these pics ? What do you think ? Where exactly is the weakest point on a three piece double edge razor ? 

This is but one (amongst myriad) reason(s) why tatararazors are the best engineered modern DE razors.

The more you know....

Is the closest thread to the top cap the weakest point?

The weakest point of a three piece DE razor is the fact that you have to disassemble it to put a blade in it!

An interesting point.

Actually the "weakest point" is the first couple of threads exiting the bottom of baseplate ,when the cap is attached to the  
latter. 
Those bear most of the load (= clamping force between baseplate and top cap ) .
Over-tightening regularly will weaken gradually those threads until failure
 ( stripping or galling*depending on the material of top cap threads and handle threads  ) .

Galling can easily occur,even at low speeds.All it takes is over-tightening.
Especially on fine threading ( not so much the case with Μ5x.8 or 10/32 threads used on most DE razors )

Aluminium ,brass,bronze,copper and Zamak alloys are soft and prone to thread stripping .

Titanium,Aluminium and austenitic stainless steel ( 3-- series ) alloy threads are prone to galling .  

Conclusion : Avoid over-tightening .

I've yet to see any broken threads or galled threads on a top cap from a razor that's not Zamak.

Well,many vintage brass razors have 
semi-stripped or totally stripped threads.
I've come across plenty of them.

From the other hand s.steel,titanium,bronze and aluminum alloy razors are being made the last 5-10 years ,so it's still pretty early for failures to start appearing.

Would it be more likely to be damaged if a wahser was used?

Would it be more likely to be damaged if a wahser was used?

Placing a washer ( ~ 1 mm thickness ) between the plate and handle will effectively remove 1.25 x of a thread
( M5 x .8  standard threading )  . Depending on the total number of threads engaged by the handle ,the force applied on the first couple of threads is now x% greater ( less threads are engaged in order to apply the same amount of clamping force .Since this force is not linearly
divided at each thread ,but logarithmically stresses more the first engaged threads ,rather than the last for the Bolt-nut #1 scheme such as the top cap-plate-handle joint ),
so yes a nylon washer will negatively affect
the threading .

More than a few vintage designs used LONG top cap threaded pins ( "screws" ) to counteract the soft brass alloys used .
More threads engaged means lower axial 
loads applied on the threads.The top caps 
where usually casted and the threading was done afterwards down the line .

For modern CNC milled razors this is 
somewhat both expensive and time consuming to make ( longer cap screws ).Thus ,most ( with only couple of exceptions ) modern CNC milled razors tend to have short top cap screws ,which means 
larger axial loads applied on threads.