Why are we building our own blades?
In 2011 when Chris & I decided to build planes we had many intense discussions about what type of moulding planes we wanted to build. My initial reaction was to follow in the footsteps of the giants, Larry Williams and Don McConnell of Old Street Tool, Inc (then Clark & Williams) and build traditional style moulding planes.
Chris had other ideas, wanting to apply his creative energies to the design of a new style of molding plane. We also wanted to help Shannon Rogers’ Hand Tool School students, creating a product that we could make more efficiently to get into their hands sooner.
What we ended up with was new top escapement molding plane with many distinct advantages:
- they are ambidextrous and easily cut from the left or right (Shannon & I are both lefties) which helps with reversing grain;
- the bodies are wider so they are more comfortable to hold and use; and
- the tang is the full width of the blade so it is easier to adjust and stays in place more readily.
So we have this unique design with many favorable characteristics and we go shopping for a blade. Good luck! Full width blade, tapered ease of adjustment and secure lock? Not to be had out there unless we wanted to custom order in very large quantities.
Now you know why we set up our own machine shop to build blades. Such is the joy of design and creation.
As you may know from my first blog post, all of this is quite new to me. When we started in 2011 I had to specialize in the metalworking end of the business as we needed blades. Of all the processes involving the building of the blades, heat treating was the toughest to learn.
When you are dealing with manufacturing blades on a mass scale the process is a science. If you are doing it on an artisan level as we are, it is very much practice, art and instinct. I started with a lot of online and library research.
The best resource I found was Ron Hock’s book, The Perfect Edge, which gives a concise explanation of the chemistry of steel and the transformations it goes through in the heat treating process. If you want to actually see someone heat treat a blade, buy Larry William’s video Making Traditional Side Escapement Planes. This one book & one video were invaluable.
However, with all the information it still took me a lot of wasted steel before I got this process right. It was not just the cost of the steel, it was the many hours of labor making the blades up to the point of heat treating them and then messing up that really cost.
After heat treating there is a layer of carbonization on all surfaces of the steel. This needs to be ground back to raw steel. I leave the blades a few thousand’s over-width in the initial milling to compensate for this process. (below)
All profiles have to be re-milled. In the case of the hollow (above) I need to use a carbide end mill to cut the hardened O1 steel.
Grinding the profiles and the bevels must be done very slowly and carefully now as overheating them will destroy the temper of the metal that has been created during the heat treating process.
The final finishing is again done by hand. 1″ of the face is lapped on diamond stones for complete flatness. I work up through the grits alternately creating a burr from the profile and then lapping the face up to the next grit. I work the face up to 1200 grit.
So there you have it, 4 hours later (8 hours for the pair, in a week long process), a finished blade is ready to go to Chris for final fitting. It is a pretty simple process once you have done it a couple of hundred times. I still get the odd discard, but I am getting better and better every day!
P.S. You probably have to be 50+ to the get joke reference in the last line (hint: line from a movie). Give me your guesses/answers of what the movie title is in the comments and I will draw from the correct answers for a prize!