Today is Blade Day.
I’ll get them done, all the way up to heat treat.
First, is a little video of milling the blades perimeter.
This is not something I do on every knife, but this particular blade lends itself really well to this procedure.
Besides, I have no way of getting inside the bottle opener with my grinder, and I do not like the finish left by the waterjet. It’s rough, and it tapers.
All I use the waterjet for is to replace the bandsaw, maximize material usage, and spot the holes.
All waterjet cut surfaces still get cut by me.
Also, on this model, I don’t have a good way of chamfering the inside of the opener by hand, so I cut it with the mill. After heat treat, I’ll be able to clean it up by hand with some abrasives, and it should look good.
Here’s what they look like when they are done with this operation. The tab in the center will make more sense later.
And then, since this is a wharncliffe blade, I can mill the bevels in. I’ll still grind the bevels, and then hand finish them, but this remove the bulk of the material, quickly. I built this fixture when Mikkel Willumsen was here on the NADEN project. It’s an angle plate that sits on a tilting table. I bolt that extra fixture I made a couple of days ago onto the plate, tilt the table to the angle I want, and machine the bevel. This really speeds up the process, and gives me a good start on the grinding.
When that’s all done, I go to the bandsaw, and split the blades into their individual pieces.
Now, I clean up the saw cut, and give the blade it’s final shape. I’ll go around the outside again, after heat treat with a fine belt to make everything clean, and smooth.
Cleaning up the bevel grinds before heat treat. They are rough coming off the mill, and it’s a little easier to get the bulk of the metal off when they are soft. I’ll do this again with a 400 grit belt post heat treat, and then hand satin them.
Periphery clean up on the handle slabs with the horizontals.
Next I clean up the chamfers.
A little out of order now, as I actually made the envelopes, and got the parts in the oven before I did the last two grinding operations, but I think we’ll be OK. First thing I need to do is make some foil bags for the blades to go in while heat treating. This is to control the atmosphere that the blades are in while at temperature, preventing decarburization, and scale build up.
Here’s my rig. Sorry about the dark pictures. It’s a 24″ paper guillotine on a custom made cart with foil dispenser. The trick part is the brake on the foil roll which keeps it from unspooling. That stuff is the most dangerous stuff in my shop. .002″ thick, stainless foil. It will cut you, it will cut you bad. Working with this, and pulling stuff out of the oven are the only time gloves are allowed in my shop, though I didn’t wear any on this project.
One pouch made, with 2 blades in it. 5 more pouches to go.
And now, here they are coming out of the oven. The steel is ATS-34, so they’ve been soaking a little over a half an hour at 1900*
A rough flatness check, and testing the Rockwell Hardness to verify my heat treat. Jeez married life has turned me into a fat bastard…
Here’s the inside of the oven as it’s cooling down. Temp said 1818* when I opened the door.
A quick look at a blade before it goes in the tempering oven.