If you're familiar with the tools that I make then you're probably aware that I've spent considerably effort as of late in developing a line of stainless steel hand planes. Corrosion resistant planes are something that has been requested by woodworkers for some while now, yet it seemed that no plane makers really wished to enter into making tools from these alloys.
The stainless alloys have a reputation for being hard to work and quite frankly this is quite true. You really have to be on your game when working this material and you'll go thru tooling like my family goes thru my wife's biscuits at Sunday dinner.
The choice of stainless alloy was a key element in regards to whether or not this would be a successful endeavor. I've had some dealings in my past with stainless steel. I once worked with for an industrial contractor that had a presence on site at a copper refinery and that included not only a smelter operation but also an electrolysis operation where some parts of the equipment were submerged in vats of acid and other parts where constantly exposed to acid vapors. I soon learned that these type of very caustic environments where the reason that the 300 Series stainless steels were developed. It seemed they were the only materials that survived any reasonable length of time in this kind of environment.
I don't know many people that store their hand planes in vats of acid or near acid vapors so I think the 300 Series of stainless alloys might just be a bit of over kill for use in the making of a hand plane. I took my lead from knife makers. It seems they've had success for quite sometime with the 400 Series stainless steels and their applications include hunting knives which are exposed to the outside elements as well as to blood. I reasoned that woodworkers sometimes expose their tools to blood as well but usually accidentally. Obviously knife makers have had success with the 400 Series alloys for this application and when you consider that a hunting knife may contain parts that are hardened, some parts can be differentially hardened and some parts are still in their annealed state. This bears mentioning because whether or not a material is hardened also has an effect on the corrosion resistance as well. Also in my research I also learned that surface refinement also had an effect on corrosion resistance. Corrosion will understandably begin in areas where the metal contained rough more unrefined surface.
Taking all this into account I decided to so some experimenting of my own. I planned to use this material for the body of the plane in it's annealed state so I placed a scrap of the 410 stainless on the front steps of my shop and left it for 4 weeks. I prepped this piece by lapping the two flat sides on 220 grit sandpaper and left the edges rough. During this period of time it rained on several occasions, the temperature range from 14 to 60 degrees during this period so condensation formed on the piece and in a couple of instances ice formed on the piece overnight. Below is the picture I took when the piece was first placed on the step.
I performed an inspection of the porch step sample today. It looks just as it did the first day I put it out on the steps, even the rough edges showed no signs of corrosion. Of course I wouldn't suggest that anyone store their stainless bodied planes on the outside steps of their shop especially considering that the high carbon blade would certainly rust. Below is a picture of the sample after 4 weeks outdoor exposure.
The other consideration is that 400 Series stainless is magnetic which increases the ease of work holding and anyone one that has done much machine work knows that work holding is paramount to good machine work. All these factors lead me to believe that the 400 Series alloys may be the most ideal alloy for plane making.
On a lighter note....I've been working to complete some planes in time to ship them off in time for the Christmas holidays. A pair of rosewood infill "J" planes were the first to leave.
For as long as I can remember, well maybe not that long, but it seems as long as we've had children one of the holiday decorations that we've used in our house at Christmas has been a little train of letters that spells the word "Noel". Children have great imaginations and one day when I looked over at the little train it did not spell "Noel". See picture below.
Maybe you had to be there, but I about spit out my coffee laughing when I saw this. I've always told my children to never let a good education go to waste, I guess this is the result.