Spyderco SPY27 Steel Test – This time it is the steel in focus, not the knife.
Specific steel testing isn’t something I normally do, so this is more of an informal test and a look at a steel that was specifically designed for Spyderco – CPM SPY27. For the ultimate in technical analysis of steels please make sure to visit Knife Steel Nerds; for something lighter read on here.
In terms of composition, it is similar to CPM S30V and CPM S35VN, with comparable edge retention and toughness. More notable is that due to the changes in certain elements SPY27 is considered to be easier to maintain with a strop and to sharpen.
CPM SPY27, is a particle metallurgy stainless steel produced exclusively for Spyderco. SPY27 is intended to deliver an excellent balance of edge retention, toughness, and corrosion resistance.
Join me in this Spyderco SPY27 Steel Test for an overview of this steel.
What’s in the box?:
This really is a by-the-by section, as the knife is not the focus of this article. It happens that the SPY27 blade being tested is in the excellent Shamen knife previously reviewed in detail here Spyderco Shaman – The knife that nearly passed me by.
Two Shamen, the previous review knife, and the one featuring the SPY27 blade.
The test knife:
To distinguish those knives using SPY27 they are fitted with cobalt blue colour handles.
The Factory edge up close:
Followers of Tactical Reviews will know my views on factory edges, but to recap:
Anyone using a knife will need to sharpen it. That first factory edge is just like the first tank of fuel that a new car comes with (or first charge of the battery).
A good factory edge is a ‘nice to have’ but not a ‘make or break’ for a good knife, as you will be putting your own edge onto it soon enough.
The factory edge does however indicate the care a knife maker has put into the final finish.
It is for this reason Tactical Reviews measures factory edge sharpness and specifications, and includes this information in the detailed technical testing.
As a further look at the factory edge, this section has been added to include some high magnification photos of the factory edges.
In particular here, as we are focusing on the steel, the intention of the magnified edge images is in relation to the refinement of the edge that the steel allows.
Spyderco’s consistency of factory edge and edge finishing is excellent, and these images confirm that the steel supports this very well.
CPM SPY27 Composition:
Carbon (C):1.25
Chromium (Cr):14.00
Cobalt (Co):1.50
Copper (Cu):–
Manganese (Mn):0.50
Molybdenum (Mo):2.00
Nickel (Ni):–
Niobium (Nb):1.00
Nitrogen (N):0.10
Phosphorus (P):–
Silicon (Si):0.50
Sulphur (S):–
Tungsten (W):–
Vanadium (V):2.00
How did the SPY27 perform?:
It is difficult to quantify true steel performance without a lot of specialist equipment, so as a basic and easy to understand test, I opted for a 1″ manilla rope cut test with sharpness measurements.
Once of the features of SPY27 that has been commented on is ease of maintenance, including with a strop, so while blunting it during the rope cut test, this would be followed by restoration of the edge by only a compound-loaded strop.
The videos included below run through some of the stages of the test and the sharpness measurements. The videos also illustrate the cleanliness of cut and also show TV guide paper test cuts.
Summarising the progression during the test, out of the box we have a BESS 178 edge (typically excellent Spyderco). This has become BESS 381 after 5 cuts, and after a total of 15 cuts measures BESS 378. Of note is that the BESS measurement is a spot check so repeated measurements can fluctuate slightly.
The used edge was then worked on a strop loaded with a fine metal polishing compound, and without any re-sharpening, just using this strop, the edge was brought to BESS 179. A complete recovery of the used edge to the original sharpness level.
Spyderco SPY27 Steel Test Summary
To carry out a definitive steel performance test would require many more blades with full re-sharpening stages, and ultimately be somewhat subjective. Being the first article dedicated to a steel, I can only conclude that the results of the testing employed for this article will give us a reference result for edge stability to compare others to. The figures show the degree of blunting from a common cutting test, and that after the initial blunting the blade continued to cut well.
Perhaps the most pleasing result was the full edge sharpness recovery by stropping alone. Of course most blunting is caused by rolling the edge apex, so stropping is effective to realign this, but here we have a perfect recovery after 15 1″ manilla rope cuts.
Review Videos
This mini series consists of three short form videos showing a 1″ manilla rope cut test with sharpness measurements:
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