Understanding DE safety razor parameters

[JPO]

I don't understand how there is a claim that the Blackbird is rigid at all. There are a lot of people who like the razor so you don't need a razor to be rigid to be good... But that razor seems the antithesis of rigid.

The point was that the razor has a unique head design that allows for different rigidity depending on the direction you flex the blade.
There is no claim that this is a rigid blade clamping at all.
You can design a razor with a floating blade, like the OREN SE.

 

[catchacoolbreeze]

The point was that the razor has a unique head design that allows for different rigidity depending on the direction you flex the blade.

What does that mean?

 

[creamgravy]

You can design a razor with a floating blade, like the OREN SE.

Try a Wardonia if you want to scramble your brain regarding blade clamping and smoothness/irritation.

Double thumbs up for a such a brilliant project.

What does that mean?

Maybe pics of the v19 compared to v21 might offer a good explanation?

 

[slimshavy]

It's clear to me now why e.g., Le Maurice from Atelier Durdan offers gaps from 0.8 mm till 2.0 mm. Previously I was convinced that it would be an aggressive razor with such huge gaps, but it actually makes tons of sense. I like big gaps now.

This is interesting to me, as I was a part of Le Maurice passaround and thread that has since been removed from the site. My impression was just that the exposure was too small and keeping it constant while increasing the blade gap was a mistake. If the exposure is around zero, you're not going to cut that closely without some pressure. If the gap is too small, that pressure won't matter, and it won't matter until the gap gets crazy large, like 1.20 or more. If it's that big, you can force a little of your skin into the gap and get it to cut closer. Which, I guess, is a backdoor way of overriding the design blade exposure -- instead of bringing more blade to your face, you bring more face into the blade.
You might find there's a sweet spot with your razor, with the gap just big enough that it doesn't clog, that you get greater improvements in efficiency from tiny adjustments to the exposure more than big jumps in blade gap. Maybe I'm wrong! But I think it would be interesting to see.

 

[JPO]

What does that mean?

It just mean there are allot of different ways you can change the shaving properties
It's a side track to the thread.

Interesting project

 

[dawid]

The Blackland Black Bird design combines a flexible and rigid blade movement that is different in two directions. The blade flexes away from the skin, while it is still rigidly restrained to avoid flexing into the skin. This also reduces blade chatter.

The point was that the razor has a unique head design that allows for different rigidity depending on the direction you flex the blade.
There is no claim that this is a rigid blade clamping at all.

Such design is not unique for Blackland Blackbird at all, and the majority of DE razors are designed like that.
Most razors (Blackbird included) have the clamping distance significantly bigger than the blade reveal parameter, what means that the blade is much stiffer in the shaving direction than in the non-shaving direction.

Testing two razors which differed only in the clamping distance was supposed to answer the question if stiffer blade in non-shaving direction has any influence on shaving experience. And it seems like the impact is significant.

Maybe pics of the v19 compared to v21 might offer a good explanation?

Now attached!
v19:
- clamp distance: 2.00 mm
- bending radius: 44.00 mm
v21:
- clamp distance: 6.00 mm
- bending radius: 22.00 mm

If the gap is too small, that pressure won't matter, and it won't matter until the gap gets crazy large, like 1.20 or more. If it's that big, you can force a little of your skin into the gap and get it to cut closer. Which, I guess, is a backdoor way of overriding the design blade exposure -- instead of bringing more blade to your face, you bring more face into the blade.

That's very interesting observation and makes a lot of sense to me.

You might find there's a sweet spot with your razor, with the gap just big enough that it doesn't clog, that you get greater improvements in efficiency from tiny adjustments to the exposure more than big jumps in blade gap. Maybe I'm wrong! But I think it would be interesting to see.

Once done with the parameters testing, I am planning to design some razors with big blade gaps and positive blade exposure, so then I will be testing what you suggest.

 

[dawid]

I started testing blade exposure before going on vacation at the end of August and tested 2 out of 4 razors planned (0.1 mm, 0.2 mm, -0.1 mm, and -0.2 mm). I have some interesting observations on the two tested, but I will share the full feedback once the other two are tested too.

Unfortunately, I need to stop the testing for at least a few weeks. I had a motorcycle accident during vacation and broke a tibia and ankle in my right leg. I am forced to use crouches for at least 4 more weeks and in the meantime, I am not allowed to put any pressure on the broken leg.
All this essentially means that I cannot stand for long in front of a mirror, so the testing will have to wait a bit...

 

[blethenstrom]

I started testing blade exposure before going on vacation at the end of August and tested 2 out of 4 razors planned (0.1 mm, 0.2 mm, -0.1 mm, and -0.2 mm). I have some interesting observations on the two tested, but I will share the full feedback once the other two are tested too.

Unfortunately, I need to stop the testing for at least a few weeks. I had a motorcycle accident during vacation and broke a tibia and ankle in my right leg. I am forced to use crouches for at least 4 more weeks and in the meantime, I am not allowed to put any pressure on the broken leg.
All this essentially means that I cannot stand for long in front of a mirror, so the testing will have to wait a bit...

You heal up quickly now! That does not sound good.

 

[slimshavy]

I started testing blade exposure before going on vacation at the end of August and tested 2 out of 4 razors planned (0.1 mm, 0.2 mm, -0.1 mm, and -0.2 mm). I have some interesting observations on the two tested, but I will share the full feedback once the other two are tested too.

Unfortunately, I need to stop the testing for at least a few weeks. I had a motorcycle accident during vacation and broke a tibia and ankle in my right leg. I am forced to use crouches for at least 4 more weeks and in the meantime, I am not allowed to put any pressure on the broken leg.
All this essentially means that I cannot stand for long in front of a mirror, so the testing will have to wait a bit...

Ow! Sorry to hear that. Heal up!

 

[Goblin]

Yikes. Wishing you a speedy recovery @dawid .

 

[spacemonkey42]

Oh no, sending healing wishes your way, @dawid!

 

[catchacoolbreeze]

Such design is not unique for Blackland Blackbird at all, and the majority of DE razors are designed like that.
Most razors (Blackbird included) have the clamping distance significantly bigger than the blade reveal parameter, what means that the blade is much stiffer in the shaving direction than in the non-shaving direction.

Testing two razors which differed only in the clamping distance was supposed to answer the question if stiffer blade in non-shaving direction has any influence on shaving experience. And it seems like the impact is significant.

LOL YES! This was exactly my thought. What is the point of even suggesting there is a thing about rigidity if all razors are considered rigid because they have a top cap that extends to the approximate edge of the blade. They literally all do that. Blackland says their blackbird is rigid because it is "supported" in the direction of the "shave plane." They all are! You can't shave any other way!

 

[Stikeyoda]

Hi guys,

Even though I’ve been here on the forum for a while now, this is my very first post.
I’m glad to join the B&B community!

I switched to wet shaving around a year ago and like many of you, got a bit geeky about it too. Over the past months I read many topics on various DE razors and got especially interested in parameters and how they influence razors’ performance and feel, as I simply find it very interesting.
Even though we can find great amount of information on the matter on the forum (e.g. fantastic Safety Razor Parameters: Illustrated and Defined thread), there are still many questions unanswered to me.

Lately I’ve been on sick leave from work for almost two months now so had a lot of spare time and one day an idea came to my mind. The idea is to test various parameters of DE razors and understand how they influence shaving experience. I’m a mechanical engineer with CAD experience, so design is not a problem for me, and on top of that I already have a 3D printer at home which I can use for printing razors.

To start with, I created a design which allows me to change the following parameters independently one by one, without influencing other ones:
- Blade gap
- Blade exposure
- Neutral blade angle
- Guard span
- Cap span
- Clamp distance
- Guard/shave plane distance (I will elaborate on it in a separated thread)

After struggling with some technicalities and printing few prototypes, I finally managed to create a razor which can be used as a baseline:
- Blade gap: 0.65 mm
- Blade exposure: 0.00 mm
- Neutral blade angle: 30 deg.
- Guard span: 2.00 mm
- Cap span: 2.00 mm
- Clamp distance: 2.03 mm
- Guard/shave plane distance: 0.1 mm

I didn’t expect much from a 3D printed razor, but after shaving with it yesterday I was amazed how decent it was, even though I am a fan of high efficiency razors with strong blade feel (my daily razors are Muhle R41 and Rockwell 6C R6). If I needed to compare, I would say it was as mild as Muhle R89 but definitely more efficient.

I will be rating razors in scale of 1-5 in the following categories:
- Efficiency (higher is better)
- Blade feel (higher is better) – I enjoy blade feel, so higher is better to me
- Smoothness (higher is better)
- Aggressiveness (lower is better)
- Alum response (lower is better)
- Clogging (lower is better)
- 1 day razor bumps (lower is better)
- Overall score (higher is better)

Since I shave every 2-3 days it will take me some months to run the test, but I hope at the end of it we can get some added value and better understanding of DE razors parameters.
I would also appreciate your help along the way - it would be nice to collect questions related to parameters which then can be investigated and hopefully answered.

Thanks,
Dawid

This 3D printed razor has gotten pretty popular here on B&B. I have one and it has become my travel razor, though a number here use it everyday.


Superior Cuts 3-D Printed Razor - https://www.badgerandblade.com/forum/threads/superior-cuts-3-d-printed-razor.647160/

 

[dawid]

This 3D printed razor has gotten pretty popular here on B&B. I have one and it has become my travel razor, though a number here use it everyday.


Superior Cuts 3-D Printed Razor - https://www.badgerandblade.com/forum/threads/superior-cuts-3-d-printed-razor.647160/

Are you saying I should start selling my razors on eBay too?
I am really impressed how popular it got, because there are reasons why I would never be willing to buy a 3D printed razor for other than testing purposes only.

 

[slimshavy]

Are you saying I should start selling my razors on eBay too?
I am really impressed how popular it got, because there are reasons why I would never be willing to buy a 3D printed razor for other than testing purposes only.

This thread opened my eyes to the possibilities of 3D printing razors. Granted, it was just baseplates, but it turned my worst razor (a Tech) into perhaps my best.

I wonder why you wouldn’t buy a 3D printed razor.

 

[dawid]

I wonder why you wouldn’t buy a 3D printed razor.

There are two primary reasons:

- They lack sufficient stiffness, which means they cannot maintain uniform parameters. For example, when bolted in the middle, the outer sections of a baseplate and top cap tend to move apart (due to compression in the middle), resulting in varying blade gap from the middle to the edges of a razor. This is why I use the side tabs during testing.
There are more issues related to tolerances and materials.

- FDM 3D printing builds objects layer by layer. Small gaps between layers on the outer and inner walls can collect germs/bacteria that are difficult to clean. That’s why FDM 3D printed items are not considered safe for food contact without additional treatment or coating. In terms of shaving, this could lead to increased skin irritation and razor bumps.

I shave a maximum of two times with a printed razor to avoid above mentioned issues.
However, I am testing parameters here and trying to be as accurate as I can, doing my best to minimize external variables. It's possible that in regular and daily razor use it doesn't matter at all.

 

[dawid]

Ok, I am kind of back to business.

This time I was after the blade exposure.
Four razors tested and compared to the baseline design (v16):
- v16: 0.00 mm
- v24: +0.10 mm
- v25: +0.20 mm
- v26: -0.10 mm
- v27: -0.20 mm

Conclusions on positive (bigger) blade exposure (v16, v24, v25):
- Bigger blade exposure has a very minor effect on smoothness, however it slightly decreases with bigger values
- Bigger blade exposure increases efficiency, blade feel, and range of a shaving angle
- Efficiency increase for blade exposure of + 0.1 mm vs. 0.00 mm is minor, but for the +0.2 mm the increase in efficiency is huge
- Bigger blade exposure increases aggressiveness, but not by much or almost not at all
- Bigger blade exposure does not increase skin irritation

Conclusions on negative (smaller) blade exposure (v16, v26, v27):
- With negative blade exposure efficiency drops dramatically. It is impossible to shave closely with the exposure of -0.2 mm
- There is no blade feel for both -0.1 and -0.2 mm exposures
- Smaller blade exposure substantially increases smoothness, providing easily gliding and gentle razor
- Smaller blade exposure causes no skin irritation, however due to exceptionally low efficiency it requires to shave same area many times


No surprises when it comes to negative exposures, unlike with positive ones (underlined conclusions which are surprising to me).
I enjoyed the +0.2 mm razor the most and used it many times lately, when I had to be done with shaving asap to overload the broken leg. It is an efficiency king with a nice blade feel, yet it's not more aggressive than the other razors I've tried.

 

[spacemonkey42]

Thanks for you terrific experiment, @dawid! I hope this means you are recovering well and feeling better. Take good care of yourself.

Your underlined conclusions are a bit surprising, but they might not be if the razor is in the hands of an expert shaver that can handle that exposure. On the other hand, they might not be the same for an intermediate or beginner shaver.

 

[JPO]

blackbird is rigid because it is "supported" in the direction of the "shave plane." They all are! You can't shave any other way!

Yes, but the distance from the edge of the blade to the edge of the top cap is really important. The stiffness is inversely proportional to deflection. This length is raised to the power of three for a cantilevered beam.
The blackbird razor supports the blade close to the edge. This gives a rigid blade in the shaving plane, while it is more flexible in the other direction. This is only useful if you use the razor as the designer intended. If you use it at a steep angle it is less noticeable.

 

[dawid]

Yes, but the distance from the edge of the blade to the edge of the top cap is really important.

The blackbird razor supports the blade close to the edge. This gives a rigid blade in the shaving plane, while it is more flexible in the other direction.

You refer to the blade exposure parameter here. Blackbird's blade exposure is not smaller compared to other razors.
Assemble Blackbird and compare the blade exposure to other razors to see what I mean.