Thread: Let's make a razor!

At least now I know what the hardest part is....Grinding the blade to an even thickness at the edge



Here I have set the bevel with a fairly coarse diamond stone. There is probably a difference of 0.1mm between the thickest and thinnest part of the blade but, as you can see this has a huge impact on the width of the bevel. When I say huge it's of course all relative.

This is after setting the bevel and going back to the grinder to try and even things out for a good few hours! I am beginning to doubt my ability to do this

We have faith in you Mike.

Originally Posted by mikew

At least now I know what the hardest part is....Grinding the blade to an even thickness at the edge

Exactly. A golfer once told me: driving is for show, putting is for dough.

The same applies to making straight razors. Anyone can produce something that looks like a razor, from a distance, and add jimps and notches and wild monkey tails. The people being able to produce razors with a thin and even bevel consistently are far fewer. I've made quite a few razors already, and I am not ashamed to admit that I don't always get there first try. Or second. Or third. I'm getting better though. Each and every razor I try to improve myself.

Anyway, that bevel looks pretty good. Did you leave the spine a bit thicker than the tang?

Cheers Jamie

Yeah Bruno, the tang has a nice taper to it starting at the shoulders. I always new the grind would be the hardest part but it really is hard!

Basically the blade is too thick in the middle so the question is, how do you grind the middle section without hitting the toe and heel?

The edge of the wheel?

looks good mike

Originally Posted by mikew

Basically the blade is too thick in the middle so the question is, how do you grind the middle section without hitting the toe and heel?

The edge of the wheel?

Eh... no. Nononono. If you want to see what happens, try it. You'll only do it once
There are 2 reasons why you don't want to make the hollow of the blade exactly the same as the rounding of the wheel.
The first is heat. A very large contact area will brun the edge quickly because of the heat buildup.
The second is this. If the hollow fits the wheel exactly, you have no margin to correct the errors that will inevitably occurr.
If the hollow is a bit less shallow than the rounding of the wheel, you have the room to grind a bit more as needed.

Now, in your case, I think I know what happened, but first tell me: how wide are your belts / wheel? If I had to bet, I'd say you used a 2" wide contact wheel?

50mm belts and wheel.

Originally Posted by mikew

50mm belts and wheel.

That's 2", and this explains perfectly what is going on. Btw, if you take a piece of wood it is very easy to simulate this in a more exaggerated manner.
Take a piece of wood and make it wedge shaped, as if it is a razor blank waiting to be hollow ground.
The length of the blank is 3", more or less. This means that you cannot grind the entire surface area at the same time. You first grind one part of the blade. Then you grind the other. And because you know what you are doing, your hollows are a bit wider than the diameter of the wheel, so that you don't make large area contact.

And now we can simulate what goes wrong: when you grind near the toe, you press just a bit harder on the toe. When you grind near the heel, you press a bit harder on the heel. As a result, these areas of the blade surface are a bit more hollow than the middle. And because you contantly correct the grinding near the edge, you'll get a pretty decent bevel, even though the are near the spine in uneven.

Take something that is very straight, like a pencil, and put it lengthwise in the hollow of the blade. If you have uneven grinding, you will find places on the blade where the pencial touches the middle of the blade, but not the heel or the toe. It doesn't even have to be much. Just like you discovered earlier: slight variations in thickness will have a very visible effect on the bevel width. The same principle holds true near the spine.

If this is what is going on, you can correct it by lightly grinding the middle of the blade a bit more near the spine.

Thanks Bruno, it's nearly 2" anyway

I'm still trying to get my head around how you grind the middle of the blade without taking too much off either end. If it was a flat ground knife I'd use the edge of the belt to concentrate on one area until it was where I wanted it, then even the grind out with a few gentle passes across the full width of the belt. Are you saying this is a no no on a wheel?