DE razor geometry. A system for measuring aggressive razors.

[Dovo1695]

Downloaded ImageJ and User Guide, will play with it this weekend!

That's awesome. I'll be curious to hear your thoughts and discoveries! It's way over my head, and I've only managed to figure out how to use scaling, measurement, area, and text notations. That's about .01% of what can do.

I know @Dovo1695 wants to try focus stacking, but this highlights why I recommended backlighting. If you focus on the blade, you can get the most important details for measuring. By backlighting you can define the profile of the razor(like the comparator). Also by putting the razor in shadow, you eliminate glare and resulting artifacts.

I don't know whether focus stacking is the best way to go vs backlit quasi-comparator, but if there are photos involved, ImageJ seems like a great tool for taking measurements of very small things. I definitely think there is merit to the idea of backlighting like a comparator. I'd like to try them both and compare the results.

I'll try anything once. I actually tried putting my razor on my photocopier and took a 600dpi scan a few days ago. My theory was that it would eliminate the optical distortion caused by normal lenses, and give you a perfect, non-distorted image of the full razor profile. It worked great except for the fact that the blade edge was 2mm above the scan plane.

My philosophy is that although I'm more or less an idiot, and I'm wrong 99 times out of hundred, I can get ahead by making more mistakes a day than most people make in a month.

 

[SCh5]

An alternative method to using photos
and image analysis software like
ImageJ is the use of a newer model iPhone 12 Pro device ,which is
equipped with a LiDar sensor,
combined with any of the 3D scanning apps available.

High precision measurments can
be extracted from a 3D model ( or
mesh ) of any given razor .

 

[Esox]

Which in turn would mean at least 5MP, whereas most consumer-grade USB microscopes offer 1920x1080p which is approx. 2MP.

1920x1080 is a good size, until you crop and enlarge to show fine detail. I use a Canon SD1200 IS 10MP that I paid $40 for. The base image size at 10MP is 3648x2736. Then normally for forum use I resize to 1080xwhatever. Below are pictures of the edge of a GEM SE blade at full resolution before and after working it on a whetstone. You need to click to expand the picture, then right click it and open it in a new tab to see the full size.

Before L. After R.



If my camera was capable of closer focusing it would do the job. This is the drawback with cameras, the lack of close enough focusing which can be overcome with lens attachments. Lighting can also be an issue.

Consumer digital camera and macro lens attachment, at least $300 excluding some sort of support

Its been a few years since I was looking at cameras for macro photography. You can get in the door at a reasonable price if you buy used. There were some good deals on eBay when I was looking and I remember almost buying a used Lumix FZ40 which at the time was one of the top macro photography cameras. I could have bought it for around $140CAD, with accessories. It would take a bit of research to find which camera would suit the purpose but I'm quite sure a deal could be found for well under $300CAD.

Could 50% of the pixels really be lost from the time the camera takes the picture and the time its downloadable from the forum?

They are actually removed to compress the image and recreated based on adjacent pixels when it is opened!

Compression loss, yep. Thats an advantage to working with RAW file format. You can do all your photo editing before any compression is done.

but this highlights why I recommended backlighting.

Backlighting is a good idea. A silhouette, a high contrast image, is always easier to see. However, the quality of the picture below isnt lacking anything as far as I'm concerned.

If that picture had a higher resolution, a more accurate measurement could be taken but how accurate does it need to be? I would think +/- .001" to be accurate enough.

 

[APBinNCA]

I'll try anything once. I actually tried putting my razor on my photocopier and took a 600dpi scan a few days ago. My theory was that it would eliminate the optical distortion caused by normal lenses, and give you a perfect, non-distorted image of the full razor profile. It worked great except for the fact that the blade edge was 2mm above the scan plane.

I love the thought of doing this! One discovery I made a couple days ago was that my cell phone camera produces at least as good an image as the USB microscope. Despite the wide angle lens, it is around 20MPx. There are a few problem to solve, but backlighting solved a big one. I won't go into what I am trying until I get something to share in a couple more days.

 

[APBinNCA]

Its been a few years since I was looking at cameras for macro photography. You can get in the door at a reasonable price if you buy used. There were some good deals on eBay when I was looking and I remember almost buying a used Lumix FZ40 which at the time was one of the top macro photography cameras. I could have bought it for around $140CAD, with accessories. It would take a bit of research to find which camera would suit the purpose but I'm quite sure a deal could be found for well under $300CAD.

You are correct, I spent an hour between B&H and DPReview yesterday. I didn't realize that newer compacts have a macro mode with a very close focusing distance. In fact, I also discovered that even a few year old design likely won't have it. I have a very old advanced compact with macro mode, but the focusing distance is at least 6 inches. The cheapest new compacts with macro are about 150, not bad, but not the budget @Dovo1695 was going for. You also need to buy a light source and a tripod if you are starting from zero because he wanted to figure out a setup any member could easily purchase and produce similar photos for comparison.

 

[APBinNCA]

Backlighting is a good idea. A silhouette, a high contrast image, is always easier to see. However, the quality of the picture below isnt lacking anything as far as I'm concerned.

We are in agreement there. I was addressing several problems all at once including the desire to replicate the comparator. The photos I post coming up will be back lit because I will be using my cell phone in the spirit of low budget. I could set up a product photo tent and lighting, but then we are getting well out of the realm of budget.

 

[Dovo1695]

We are in agreement there. I was addressing several problems all at once including the desire to replicate the comparator. The photos I post coming up will be back lit because I will be using my cell phone in the spirit of low budget. I could set up a product photo tent and lighting, but then we are getting well out of the realm of budget.

There's no budget. From my perspective, the sky is the limit. Personally, I'm working with a $50 budget, but I'll be the one cheering the loudest if somebody has a great idea and spends $500 on a setup that gives super accurate readings.

I like the USB microscope idea because it's $40 and I think we've only used 30% of what it's capable of (we've only used 1 of it's 2 megapixels for example), but I don't doubt that a real camera with a 20mp, a macro mode, and a 30x optical zoom like the Lumix DC-ZS70 would take incredible pictures.

 

[APBinNCA]

There's no budget. From my perspective, the sky is the limit. Personally, I'm working with a $50 budget, but I'll be the one cheering the loudest if somebody has a great idea and spends $1k on a setup that gives super accurate readings.

I like the USB microscope idea because it's $40 and I think we've only used 30% of what it's capable of (we've only used 1 of it's 2 megapixels for example), but I don't doubt that a real camera with a 20mp, a macro mode, and a 30x optical zoom like the Lumix DC-ZS70 would take higher resolution pics.

I think the idea is to find the most cost effective solution. I am sticking with low budget because I don't want to make this an all day setup for what amounts to a couple razors I have. Along with researching cameras, I spent some time reading reviews of the various USB microscopes. The conclusion appears to be that they are terrible unless you already have one! The thing is, it's not just the resolution of the sensor. It's the quality of the sensor and the optics and especially the focusing mechanism. Realistically, we aren't photographing all that close compared to inspecting blade edges. In the photography world, we are working at .5x-.75x, I have difficulty with ambiguous numbers like 20x magnification. Macro photography vs Microscopy records images relative to their size on the image sensor. A 6mm portion of a razor on a 8mm wide sensor. 0.0022mm pixels etc. The advantage to a USB microscope, other than it's what you have, is it's all in one. I just personally see the advantage of even a cheap compact camera outweighing the advantage in spite of the additional items needed. In fact, a cell phone clamp with a tripod mount would give the USB microscope a run for it's money as I intend to prove!

 

[Dovo1695]

This is and interesting option. I know absolutely nothing about cameras or photography, so I have no idea if this is any good, but we've probably all got smartphone cameras. Adding a 15x zoom for $45 fits the budget. I don't know what the implications would be for measurement accuracy though.

https://www.amazon.com/Xenvo-iPhone-Camera-Lens-Clip/dp/B01A6D2JVI/ref=sr_1_3?dchild=1&keywords=macro+lens+for+smartphone&qid=1623534865&s=electronics&sr=1-3

 

[APBinNCA]

This is and interesting option. I know absolutely nothing about cameras or photography, so I have no idea if this is any good, but we've probably all got smartphone cameras. Adding a 15x zoom for $45 fits the budget. I don't know what the implications would be for measurement accuracy though.

https://www.amazon.com/Xenvo-iPhone-Camera-Lens-Clip/dp/B01A6D2JVI/ref=sr_1_3?dchild=1&keywords=macro+lens+for+smartphone&qid=1623534865&s=electronics&sr=1-3

Yes, this very much is the right direction IMHO. I was going to mention this after I tested it, very familiar with this

 

[Dovo1695]

Its been a few years since I was looking at cameras for macro photography. You can get in the door at a reasonable price if you buy used. There were some good deals on eBay when I was looking and I remember almost buying a used Lumix FZ40 which at the time was one of the top macro photography cameras. I could have bought it for around $140CAD, with accessories.

If you're still thinking about it, there are a couple of those on the big auction site with under $100 Buy It Now pricetags at the moment. One sold this morning for $99.

 

[APBinNCA]

If you're still thinking about it, there are a couple of those on the big auction site with under $100 Buy It Now pricetags at the moment. One sold this morning for $99.

There is a Lumix LX7 on there even cheaper. Large sensor, good optics, macro mode.

 

[APBinNCA]

Also Fujifilm x10 and Olympus zx-1. All three are larger sensor compacts with RAW mode. I don't see the use for a super zoom type if you already have a USB microscope, the optics will be compromised.

 

[Rosseforp]

There's no budget. From my perspective, the sky is the limit. Personally, I'm working with a $50 budget, but I'll be the one cheering the loudest if somebody has a great idea and spends $500 on a setup that gives super accurate readings.

I like the USB microscope idea because it's $40 and I think we've only used 30% of what it's capable of (we've only used 1 of it's 2 megapixels for example), but I don't doubt that a real camera with a 20mp, a macro mode, and a 30x optical zoom like the Lumix DC-ZS70 would take incredible pictures.

My Plugable was only $40, but my stand and the vise bump the cost up quite a bit. Right now I am looking at Nikon V-12 comparators used as soon as I get the space. They have a nice rotating table, we had one at work. Most likely around $1000 with shipping, but I will be using it for a lot of other things.

 

[Rosseforp]

I think the idea is to find the most cost effective solution. I am sticking with low budget because I don't want to make this an all day setup for what amounts to a couple razors I have.

I'm going with an optical comparator like a Nikon V-12 because that is what I used at work as a machinist the last 45 years, and I will be using it for more than just razors. The main drawback it the amount of workspace they take up, being the size of a large refrigerator. Not to mention the light bulbs usually cost upwards of $50 -$150 each. That is why you can find them for $250 used. Then there is the shipping cost. For $1000, I can get something pretty decent to check parts and razors with. That is what I paid for my Nikon D610 with a 50mm lens.
For now, I just need to get my fixturing more consistent and upgrade my software.

Been busy looking at houses!

 

[tamahagane]

I think I get it. It looks like you're measuring the total blade clamping surface area as an indirect measurement of rigidity. Is that correct?

As a side note, I've never noticed it before, but that Rockwell guard has an absolutely massive guard muzzle area. It's nearly as big as the one on the Henson. In order to increase the blade exposure you would have to use a huge amount of pressure. I'm guessing that's a predictable razor that rarely bites.

You are correct, I intend to measure rigidity by calculating the clamping surface. More clamping => less blade vibration.
I think that muzzle area can be a substitute of razor cap curvature, but one thing is bugging me. You draw a plane where the blade edge ends, then another where the first grind level starts and calculate the surface based on that. What I am thinking is that if you are using something like a R41 or Ikon OC, then you need barely any pressure to increase the exposure twofold; OTOH, with a FOCS you don't have this option. Maybe Gillete Tech and clones are the same, but I have never owned one so cannot comment. In the case of very aggressive razors, the blade support is virtually nonexistent, so the muzzle area would be 0. This in turn would mislead any classifier (except maybe Neural Networks), so if muzzle area is measured, it should be a separate parameter, leading to more than the current 3.

As far as the Rockwell is concerned, R1 and R2 do actually shave. The skin must be stretched for that. As for R1, it works only on a day's growth for me, otherwise I need to go ATG.

 

[JPO]

You are correct, I intend to measure rigidity by calculating the clamping surface. More clamping => less blade vibration.
I think that muzzle area can be a substitute of razor cap curvature, but one thing is bugging me. You draw a plane where the blade edge ends, then another where the first grind level starts and calculate the surface based on that. What I am thinking is that if you are using something like a R41 or Ikon OC, then you need barely any pressure to increase the exposure twofold; OTOH, with a FOCS you don't have this option. Maybe Gillete Tech and clones are the same, but I have never owned one so cannot comment. In the case of very aggressive razors, the blade support is virtually nonexistent, so the muzzle area would be 0. This in turn would mislead any classifier (except maybe Neural Networks), so if muzzle area is measured, it should be a separate parameter, leading to more than the current 3.

As far as the Rockwell is concerned, R1 and R2 do actually shave. The skin must be stretched for that. As for R1, it works only on a day's growth for me, otherwise I need to go ATG.

The blade rigidity is governed by how far the cap extends past the end of the base plate support, the blade cantilever length past the end of the base plate support. You also have the fulcrum support and the flat support ( e.g. karve razor) differences. A fulcrum base plate support takes advantage of the spring force from the curvature of the blade.
The actual clamping surface is not that important. It is much easier to calculate the blade rigidity for the simple flat plane support.

 

[tamahagane]

The blade rigidity is governed by how far the cap extends past the end of the base plate support, the blade cantilever length past the end of the base plate support. You also have the fulcrum support and the flat support ( e.g. karve razor) differences. A fulcrum base plate support takes advantage of the spring force from the curvature of the blade.
The actual clamping surface is not that important. It is much easier to calculate the blade rigidity for the simple flat plane support.

Do you mean the free-end distance or clamping distance by cantilever length? Looking at the Karve website, I could not see any explanation of the different kinds of clamping, so I assume this has been discussed in the forum - can you provide a link or an illustration? Or perhaps a sample calculation for a razor you have?

 

[JPO]

I can provide some sample calculations, just need some time.
As the the top cap extends past the end of the base plate support you create a support, almost like a fulcrum, which alters the blade rigidity. A good example of this is the rex ambassador.

 

[Dovo1695]

You are correct, I intend to measure rigidity by calculating the clamping surface. More clamping => less blade vibration

This is not necessarily true. The quality of the clamping, and the distance of the clamping area from the edge of the blade are much more important than the total surface area of the clamping. Modern CNC razors that clamp a razor like a vise a few millimeters from the edge don't need a lot of clamping surface area to get into the 99th percentile with respect to rigidity.

There is also the issue of diminishing marginal returns. You might capture 95% of possible rigidity with 0.5mm x 44mm of clamping surface area if it's clamping like a vise near the edge. Extending that clamping surface area to 5mm x 44mm might only improve it an additional 1%.

That's how it works in my head at least, but I'm am wrong about a lot of things like this.

You may well be right about clamping surface area. If I was to try and measure this, I would get an egg of silly putty. Spray a razor with cooking spray or wipe with machine oil, and put the razor in the freezer for 30 minutes. When the razor is frozen, I would put a small strip of room temperature silly putty in the clamping area. Clamp down with the razor and put it back in the freezer. The low temp will remove all elasticity. Take it off the razor. You will see areas where the clamping actually occur, and where poor quality of casting causes it not clamp. Take a photo with a mm ruler for scale, and measure it in image J. You could try modeling clay too, but I'm guessing it would be really hard to get off intact. Just a thought.