Spike Knife

The WRCA annual knife show ran May 19 and 20, 2018.  There were amazing knives and my friend, Skip gave me spike knife.  I’m still smiling when I look at it.

Skip's Spike

Skip does some amazing blacksmithing and like almost every blacksmith he has made more than a few railroad spike knives.  RR spikes are described as “…the most widely recognized pieces of railroad equipment by the general public.”  They were invented by Colonel Stevens who was also the inventor of the current rail configuration.  You’ll find them in different lengths, widths and thicknesses depending on the manufacturer, installation location as well as the type of wood the ties are made of. 

I was surprised, but I should have realized it, there are many collectors of RR spikes.  Some spikes have the year they were made molded into their head,  Historically different manufactures used different dimensions that changed over time, all of which makes them collectable.

Standardization came with the mechanical age and American Society of Testing and Materials was a big part of it.  ASTM 65-07 (2013) currently regulates the quality of railroad spikes.  ASTM is a for-profit organization and not being a member, I can’t access the standard.  However, I was able to find out that there are two types of RR spikes: soft and high carbon.

As carbon levels increase, strength increases but so does brittleness.  It would be a poor spike that cracked every time a train rode over a section of track.  The soft spike should contain no more than 0.12% carbon and the high carbon has a wopping 0.3%.  To put this in perspective, 1095 steel has 0.95% carbon and many super stainless steels have very high carbon levels.  For example, the super steel CPM S90V steel has 2.3% carbon. 

So, a RR spike might be able to be sharpened, but the low carbon levels prevent it from retaining its edge.  Fear not, you can change that, but you better be fearless.  You can case harden your spike knife.  Case hardening introduces increased levels of carbon to a thin layer of steel, essentially creating a sheath of high hardness material.  One relatively straight forward method is cyaniding.

Cyaniding is a case-hardening process that is fast and efficient; it is mainly used on low-carbon steels like RR spike knives. The part is heated for 20 to 30 minutes at a temperature of 1600-1750 °F in a bath of sodium cyanide and then is quenched.

This process produces a thin, hard shell (0.01 and 0.03 inches thick) which is harder than the layer produced by carburizing.  Magazine lips on early Colt semi-automatics were treated this way in the early 1900’s.  The major drawback of cyaniding is that cyanide salts (and I’m speaking as a chemist here) are very poisonous.  I told you that you needed to be fearless. 



No, I’m just going to enjoy my spike knife just as Skip made it.  You can find Skip at Airedale Custom Blades on Facebook.