What do I need to do to prevent part of an armor from deforming with the skin modifier?

[MikeJones84]

I made an armor that has some parts that are supposed to be solid but are being deformed like melted plastic because of the skin modifier. How can I get these parts to move without deforming with the skin modifier? I have very little experience with skinning besides using skin wrap and some basic weight painting. I'm using 3DS Max 2012.

[JRCosta]

A screenshot of the problem could be helpful.

 

In any case, the trick is to assign all the selection that you want to remain unmoved to be the same weight influence (1) of the base mesh main bone. 

 

For example, imagine that you have a long spike metal starting from the shoulder (clavicle bone) moving opposite to the body alongside the neck line; it will bend influenced by the forearm twist and the other arm bones; you change the weight of all that spike mesh section to 1, so when only the clavicle moves, all that section moves too without any influence of the arm bones.