Why Isn't My Wedge As Sharp As My Hollow Ground?

[mjclark]

I'm rapidly learning that the best thing to do is ask, so here goes:
I'm getting very satisfactory results and nice shaves off a 3/8 wedge and a 6/8 extra hollow ground.
But I'm really noticing that although I'm putting both blades through the same honing regime (0.5k/0.7k whetstone, 6k slate, 8k barber hone, 10k lapped hone, CrOx, horsehide) they are behaving very differently.
Although smooth and doing a lovely job, the 3/8 wedge simply refuses to become as sharp as the 6/8 hollow ground and I am hoping someone can explain why.

Do wedges need a more aggressive bevel?
Obviously the physics are different, but how does this translate practically for different honing techniques.
Ha ha- there's a lot to this, isn't there...?

 

[Gamma]

Sharp means a lot of things. There are a lot of unknown variables here, so it's too hard to say what's what.
bevel angle, steel type, lack of experience, etc, all that and more will factor into the results.
It's entirely possible that the bevel on the wedge isn't 100% there yet. Generally, a lack of sharp/smooth can be traced back to the bevel.
Without seeing and/or knowing the razor it's impossible to say though.

 

[mjclark]

Sharp means a lot of things. There are a lot of unknown variables here, so it's too hard to say what's what.
bevel angle, steel type, lack of experience, etc, all that and more will factor into the results.
It's entirely possible that the bevel on the wedge isn't 100% there yet. Generally, a lack of sharp/smooth can be traced back to the bevel.
Without seeing and/or knowing the razor it's impossible to say though.

Yeah- I'm so new to this and there's so much to discover!
I'm getting really nice shaves from my straights now, so I know that to some extent I'm getting it "right".

But at the same time, I'm noticing differences that I haven't yet got an adequate vocabulary for.
Is there a glossary of honing terms somewhere?

For instance, when I stropped on newspaper the edge ended up feeling "brittle" in a way which it doesn't with the CrOx.
And of course differences in the actual steel.
But I'm really getting the idea that the bevel is the fundamental and essential foundation of everything that is to follow

 

[Gamma]

Yep - the bevel is the foundation.

There probably is a glossary somewhere in the Wiki. I seem to remember there being one someplace.

 

[Slash McCoy]

Is your wedge a true wedge or a near wedge?

One thing you could do if you are of a curious mind, is to measure and calculate the bevel angle for both razors. On the wedge, if you hone with tape, be sure to include tape thickness. Bevel angles of wedges vary greatly, even without considering tape on the spine.

My recipe for a sharp wedge is as follows. First of all, I measure and check the fundamental bevel angle of the razor. It should be at least 14-1/2 degrees but not over 17 degrees. Then I hone hone hone hone hone, without tape. After completing the progression, I then tape the spine with one layer of tape, and do maybe 30 light laps on my finishing film. With a true wedge, the entire blade, practically, is the bevel. It is difficult to get a perfect edge under these conditions. A secondary bevel is much easier to get right. Now with tape on the spine, obviously the bevel angle of the secondary bevel or micro-bevel is somewhat fatter, which is why you can use a razor with a fairly skinny primary bevel angle. The taped spine increases the bevel angle by typically over one degree. And the compounded bevel lets you get away with even the secondary bevel being slightly on the skinny side.

This is all a lot of work which is one reason I don't care too much for wedges. BUT... when you got a wedgie dialed in correctly, it can give a really good shave. Sharp is do-able. It's all about the bevel, and honing knowledgeably as well as skillfully and patiently. Setting a full blade tapeless bevel on a wedge can take a lot of rubbing.

Vintage wedges often have too fat of a bevel angle because many honers run their whole progresson on wedges with the spine taped. So the spine stays at the original thickness, forever, while the blade width is slowly but constantly reduced, so that after many many years, the bevel angle becomes too fat to have the same cutting power as when new. Nothing for it but to rub rub rub on the coarse rocks, with pressure on the spine. Keep going until the new bevel meets the other side at the edge.

 

[mjclark]

Well the 3/8 has very slightly concave sides, so I guess that makes it a near wedge...
...what's the best way to calculate bevel angle?
Do I use the width of the spine, the length of the blade and trigonometry or is there another way?

 

[gary haywood]

if you google bevel calculater, something should pop up..there was one on coticule.be? just carn't seem to find it. Like slash say adding a layer of tape realy works.. wedges can be more difficult than hollows as there is more steel to remove, Most guys I no that are into wedges use 2 layers of tape ....

 

[Gamma]

Honing a wedge isn't a great big deal.
They are not harder to hone than full hollows.
In many ways they're actually easier.
If the blade is trashed, that's one thing - then you have a lot of work to do.
But you can lean on it without worrying and if there's pitting you can usually cut through to clean steel easily enough.

Factually - steel/edge condition non-withstanding - if the same amount of steel is on the stone, then honing a wedge is the same as honing anything else.

For wedges - I often use 1 layer of tape, rarely 2.
But - only when I need to. If I don't need tape then there's no need to use tape.
Generally - if the bevel is really wide, and the spine wear is very prominent - then 1-2 pieces of tape will fix things up.

IMO - a properly honed wedge shaves as well as or better than anything out there.

 

[mjclark]

if you google bevel calculater, something should pop up..there was one on coticule.be? just carn't seem to find it. Like slash say adding a layer of tape realy works.. wedges can be more difficult than hollows as there is more steel to remove, Most guys I no that are into wedges use 2 layers of tape ....

Thanks- I found the coticule.be calculator.
Looks like the bevel on my 3/8 is just over 16 degrees, so I guess it's OK
It gives a great shave, so maybe it's just the feel of the blade, since the edge is less flexible than the hollow ground...

...also I should be receiving a 5/8 wedge shortly- if the bevels OK do I hone without any tape?
And if the bevel needs attention, do I hone through the progression without tape, and then tape and refinish, or do I tape through the entire progression?

 

[drmatt357]

IMO - a properly honed wedge shaves as well as or better than anything out there.

+1 for sure here Gamma😌

 

[Doc226]

I would guess your wedge is not honed to it's full potential.

I think setting a bevel on a wedge is harder, once it is set the rest of the honing is pretty much the same.

The "sharpenss" onced finished should be the same as anything else.

 

[Slash McCoy]

Well the 3/8 has very slightly concave sides, so I guess that makes it a near wedge...
...what's the best way to calculate bevel angle?
Do I use the width of the spine, the length of the blade and trigonometry or is there another way?

First, look at your razor's spine. There should be a flat strip where the spine bears on the hone when you are honing. This is part of the bevel. The other part is at the edge. Now pick a point on the back edge of this spine bevel. That is, the edge of it furthest from the shaving edge. At that point, measure the thickness of the spine. It will probably be the thickest point on the spine so that makes it easy to measure with a dial caliper or micrometer or vernier scale. Make a note of that measurement. Now, from that same point, measure to the absolute edge of the razor. Write down that measurement.

What we gonna do is solve for the acute angle of a right triangle where we have the opposite leg, and the hypotenuse. The opposite leg is HALF of the first measurement, which we will call spine thickness. Why half? Because if you use the whole measurement, you are messing with an isosceles triangle, not a right triangle. We are taking the isiceles traiangle and breaking it up into two right triangles to solve it easier. The right angle is buried deep within the center of the spine. The acute angle is at the edge, and is half the bevel angle. But back to the math... Sine = Opposite/Hypotenuse. You got the Opposite side, half the spine thickness. The other measurement is your hypotenuse. So divide half the first measurement by the second measurement and you got the sine of the angle. On your calculator look for the inverse sine function. Or on your Windows Calculator, put it in scientific mode (VIEW menu) and hit the "Inv" button and the SIN button turns into a SIN-¹ button. Hit that one and you get the angle for that sine. Double that angle and you got the bevel angle. Easy sneezy.
A near wedge can normally be honed without tape. Unfortunately the previous owners may have used tape anyhow, and eventually honing with tape makes for a fat bevel. A heavy bevel gives a nice gentle shave. Unfortunately if it is really thick, you lose cutting power. And a heavy bevel can't tolerate much convexity, either, whereas a skinny bevel thrives on a little convexity. Anyhow see what you got for a bevel angle. The fact that you did get it to shave tells me that your basic technique is not at fault. Your razor just has issues. Or it coud be your shaving technique. What is great about wedges is they are relatively heavy. More mass than a hollowground of the same size. So more inertia when you got it moving. Try brisk strokes and be sure the razor is in motion before it contacts whiskers. That way you get the advantage of the extra mass. Also try honing on 1u film without paper underneath, and with lather for the finish. This gives a super flat bevel that could be harsh with a skinny bevel angle but might be just the thing for a fat bevel if that is what you got. You could also try stropping a couple hundred light laps on balsa with .1u diamond paste rubbed in well. Light pressure because you don't want to use the resilience of the balsa to give convexity... you want a really flat bevel surface if you have a fat bevel angle. Diamond on a hard leather bench strop could work, too.

 

[mjclark]

Thanks for the help so far guys!
I guess the bevel calculator just does the trig for you, and the bevel angle on that 3/8 wedge is looking OK at just over 16 deg.
I'd also wondered if the problem was more to do with my shaving technique- 3/8 and also a wedge is yet another learning curve to ascend
It's a privilege to have access to so much experience and informed advice
I'm really looking forward to that 5/8 wedge arriving now.

I'm also very interested in hearing how people define and describe what "shave ready" means to them.
I've got a couple of razors coming in the post from a guy who's been restoring straights for a long time, and has been using the razors he's sending me himself, so it will be really useful to actually experience what a properly honed edge is like.
Then I will have some kind of benchmark to compare my primitive results with