Introduction: Tanto Blade Letter Opener
Before we start. The goal for this project was increasing my skills hand lapping and polishing surfaces. To be precise flas surfaces.
In the end this was a great excersize but in the end the surfaces were not a mirror finish but I learned how to improve here. So this was a succes in my opinion!
I have plans and drawing available for this little letter opener, you can find them on my website.
Step 1: Design
So why did I choose to make a Tanto blade? Well for a few years I find the design of these blades very elegant. I wanted to give it my own twist so i made it very angular. A traditional Tanto sword or dagger have a much more curved edge. And they are quite a bit longer. between 20 and 30 cm. about 8 to 12 inches if I interpret Wikipedia correct.
This project has a single bevel, a tanto with a single bevel is named a: Tanto Kata Kiriha.
Step 2: Rough Shaping With the Grinder
The piece of material was a leftover cutoff from a file. This was annealed in a previous project. This project (Kiridashi knife) is also on Instructables.
This proces was quite straight forward. I used the grinder to cut away steel and grindd the final shape.
Step 3: Grinding the Bevel
Usually a bevel is ground to the blade with a stationary grinder or sanding machine. I personally don't have that so I had to rely on a steady hand and a grinder. This takes a bit practice because you try to use a grinder like a pen :p with these small movements.
After this I used a file to gently smooth the ground surfaces. And at the root of the edge I made a half round relief with a file. This makes the handlapping a bit more easy and neatly.
Step 4: Hand Lapping
My hand lapping or sharpening gear is quite basic. But still very functional. I have a two sided oil stone and one diamond bed at 1200 grit.
The trick for hand lapping is to keep the small workpiece flat on the stone. Apply enough oil or lubricant. And make round shape or '8' shape while moving. During the movement apply pressure on the workpiece. But be careful with uneven pressure. You want the grind evenly the surface.
I spent about 80% of the time at the coursest grit level. I had to remove a lot of black metal and flatten out the surfaces. When grinding the bevels take extra care to keep the workpiece flat on it's bevel.
I followed this procedure and after a while this became more and more easy.
Step 5: Stropping
After that I used a leather strop with green stropping compound to 'polish' the surfaces.
This went reasonably well, the surfaces became smooth but the steel still had a brushed look.
Next time I am going to use sandpaper or more sharpening stones to grind more finely. Probable a few extra steps like 1500 grit 2000 grit and 3000 grit. And then do the polishing step.
The reason why the brushed look still existed because the finer grit grinding step didn't remove the steel texture from the courser grit step.
Step 6: Oak Handle
I placed the workpiece on a small piece of oak wood. This was a piece of hardwood flooring. I made a recess of the 'tang' to make the blade fit. I could use a small router for this but a gouge and chisel is just as much work. Sometimes hand tools are just as quick and precise as power tools. Not always ;)
Step 7: Epoxy
I used a Epoxy resin to attach the handle and blade. In my experience a resin is stronger than a 5-min epoxy glue. But it can't 'overstrain' gaps like a glue can. So for precise situations use a resin, for larger gaps use a 5-min glue.
Step 8: Shaping the Handle
The oak was kept oversized. After the resin set I could shape and remove the material to make the handle more fitting to the blade aestheticly.
Step 9: Finish and Testing!
For finish I used a whipe-on cutting board oil. I will use this letter opener with my hands so prefferable it doesn't need to be toxic.
And then I could check if it acutally works!
The edge is not very sharp like most letter openers but the point of the blade can easly piece the paper so this acutally works and isn't very dangerous with the dull edge.
This was the instructable, I hope you could enjoy this one!