A surface grinder uses a magnetic chuck to lock the part in place. The motor with stone is fixed in place, but can be precisely elevated and lowered by very fine increments. You change out the stones from very coarsevto very very fine. The table/chuck is geared so that you may move the part back and forth under the rotating stone.



You must be exceptionally careful to not take much off with each pass. You grind much like mowing the yard. Small width, advance another small width, advance another small width. Each pass, the stone spins over whathas already been ground. It may pick up just another raised track. You continue until that entire side has been covered, then you lower the stone/motor/Hub a half a thousandth or so. Do all the passes once again. Repeat until the side is smooth and at the thickness you require.

It's very very precise and also very time consuming. There's no other way to make excellent quality parts sets.



Note how the spark trails BURST into a STAR at the ends of their tracks. That indicates very hard high carbon steel. You can get a very wood idea of carbon content and quality from "Spark Testing". This is my Damascus Sherpa Blade!

Gary

Ahh
The green wheel ! Hey Gary you going to tell us how much the green wheels cost ??? I've used the surface grinder a lot for sharpening tools and dies . The punches we used in the strippit machineswere 7"tall and the turriet held about 40 or so different punches . Every now and then the punch would go flying off the magnetic chuck .We also had to mic how much we took off and add shims as to NOT change length of punches or height of the dies . I sure don't miss that machine at all . They do veeerrrry precision work though .

Thanks
Kurt

Interesting. Experience speaks!

These wheels are 7 by 1/2 by 1 1/4" Hub. About $60-$100 per wheel, so far as I know.

I got a group of wheels together once. I have some white ones that seem impregnated with wax/oil that lubed it as it grinds. Very precise. Very touchy to use.

It's another unknown skill that you must be capable of to make excellent folding knives. And they sure don't give away the machines.

Thanks
Gary

Gary,
That's another cool toy, I mean tool, you have to play/work with!
It is easy to see how the process would be very tedious and time consuming.
I suspect when the mass producers automate a process like this, the quality starts to go down rapidly.

Scott

Hi Scott,

Production parts have traditionally been die stamped. As a first step, there's no problem with that. But the process of stamping/shearing will produce a slightly rounded edge profile on the female die side, and a sheared (sharp) edge profile on the male die side. Now, they toss the parts into a tumbler with abrasive media and tumble them around for hours and hours. This wears off the sharp edges but still leaves the distinctive male/female die results. They aren't going to surface grind the parts at all, on 95% of production knives.

Here's the steps I add:

1). I'd blank out a slightly oversized part. Bandsaw/shear/waterjet/or laser - and then profile grind each part to final shape. This produces a square profile with the flat sides of the part.
2). I'd then surface grind each part set, to the exact and clean thickness. The flat then goes to the edges of the part. No dubbed off, mashed/rounded female die edge. No slightly larger sharper male die profile.
3). After heat treating, I'd then change stones and surface grind a finer finish texture. And remove heat treat oxidation.
4). Back to sanding the profile. We left it with about a 60 or 120 grit edge before heat treating. We now sand thru 240, 320, 30 micron, and 15 micron belts. (Each a different belt change on the machines).
5). Finally, I go to a loose buffing wheel and polish all edges bright. (Essentially a reflective mirror polish).

Now the part is flat, consistent in thickness with all other knife parts. It's edges are square and flat. It's edges are try and polished. BIG difference in process and result. If a person feels that's just silly, then Walmart sells a lock back folder for a dollar. That's right. One dollar. Industry/cutting corners/slave labor = $1 pocket knives. If your goal is just to own a cutting tool, that's a very serviceable and economical solution.

Every process on the production of my Knife or Airgun Parts, follows those five steps, and many many more. It's only worth buying if you find it intriguing that one person could accumulate the tools, machining, engineering, metallurgy, and artistic skills; to build a pocket knife from scratch. You are buying a portion of that Craftsman's Life, when you buy something he spent 40, 80, 120 hours of Skilled Expert level effort, to produce.

Thanks for Considering
Gary

I've really started to admire the surface grinder. Wish I had more room, and the money to fill it.

Lon

Lon,

That's a machine that NEEDS an environment that can tolerate an endless shower of sparks, and a liberalciating of the filth that the sparks turn into when they cool. People may not realize that a spark is a burning piece of steel. It's a tiny meteorite.

Gary