DE razor geometry. A system for measuring aggressive razors.

[Dovo1695]

Thanks for the information.

What is a foolproof way to ensure your microscope/camera is perfectly plumb over the apex of the blade so that your not introducing skew that screws up the exposure measurements?

This one has me stumped, especially with a miceoscope with less than 1 mm field of view. It's hard to be sure that you're perfectly plumb, but it has big implications for accuracy.

It's probably something obvious, but this has me stumped.

Here is a good example of why it matters. Here are two consecutive photos from a brilliant review of the Timeless Slim. Same razor, with the same blade, same photographer, 5 minutes apart. I added the red shave plane lines. The first obviously shows negative blade exposure. The second appears to show 0.15mm blade exposure. The listed blade exposure is 0.05mm. Obviously the first pic is bad, but you can see how bad the error can be in a worst case scenario. The second picture doesn't look that bad, but makes exposure measurements off by 300%.

Here is a pic of the Slim from Timeless website that clearly shows negative blade exposure on a razor listed with 0.05mm blade exposure!

 

[APBinNCA]

@Rosseforp setup is the model, I have bookmarked the post with the photo of his setup. Designing a jig to hold the razor level then making sure the rail the camera is on is level and finally not letting your brain tell you it's off.

 

[Dovo1695]

@Rosseforp setup is the model, I have bookmarked the post with the photo of his setup. Designing a jig to hold the razor level then making sure the rail the camera is on is level and finally not letting your brain tell you it's off.

You and me both. @Rosseforp's setup is amazing. Hard to replicate with my $13 Harbor Freight indicator stand on a piece of plate glass.

I'm over here with a sketchbook thinking about 40mm stainless steel cones and laser pointers and trying to make my duct tape and twine based microscope stand shoot straight.

 

[APBinNCA]

You are a wood worker, all you need is a jig with two axes(x, y) with a large enough flat area to put a level on. You could cut a length of wood and clamp it upright to the microscope base and use that to level the camera.

 

[Esox]

What is a foolproof way to ensure your microscope/camera is perfectly plumb over the apex of the blade so that your not introducing skew that screws up the exposure measurements?

This one has me stumped, especially with a miceoscope with less than 1 mm field of view. It's hard to be sure that you're perfectly plumb, but it has big implications for accuracy.

It's probably something obvious, but this has me stumped.

Here is a good example of why it matters. Here are two consecutive photos from a brilliant review of the Timeless Slim. Same razor, with the same blade, same photographer, 5 minutes apart. I added the red shave plane lines. The first obviously shows negative blade exposure. The second appears to show 0.15mm blade exposure. The listed blade exposure is 0.05mm. Obviously the first pic is bad, but you can see how bad the error can be in a worst case scenario. The second picture doesn't look that bad, but makes exposure measurements off by 300%.

Here is a pic of the Slim from Timeless website that clearly shows negative blade exposure on a razor listed with 0.05mm blade exposure!

I always tried to look directly down the edge of the blade. Visualize the blades edge and align the camera to that linear line. Think of the edge of the cap and comb in the first focal plane but midway down the blade as the main focal plane. Its not easy and takes some fiddling but the better your fiddling the better the end result...or something...someone...once told me lol.

I think the photo from Timeless is very close.

 

[Dovo1695]

I always tried to look directly down the edge of the blade. Visualize the blades edge and align the camera to that linear line. Think of the edge of the cap and comb in the first focal plane but midway down the blade as the main focal plane. Its not easy and takes some fiddling but the better your fiddling the better the end result...or something...someone...once told me lol.

I think the photo from Timeless is very close.

Holy crap, I just had a cool idea while watching a very bad movie. I don't need lasers, I need a mirror. The microscope could be self leveling with its own LED's.

 

[Esox]

Holy crap, I just had a cool idea while watching a very bad movie. I don't need lasers, I need a mirror. The microscope could be self leveling with its own LED's.

Lasers? Yes. Of course we need lasers.

 

[Dovo1695]

Lol. It actually works. I was watching a movie on my ipad. It's basically a mirror when it's turned off. I put my microscope stand on it and turned on the camera, which turns on the 4 LED's. I set the height of the camera to 50mm, which is where it's set for taking pictures of a 42mm DE razor standing on edge. If the camera is perfectly, and I mean perfectly vertical, the reflection of the led's will be centered in the picture. Like this:

My indicator stand is a ***, but even the cheap copies like mine have a fine pitch adjustment that allows you to adjust the X axis by 2-3 degrees with a full rotation of an adjustment knob on a fine pitched thread. This is what it looks like with a full rotation of the adjustment knob off dead nuts vertical on the x axis:

I can't believe that actually worked. That's some real BOSC sciencing right there boys. Frickin optics and laser beams!

 

[Esox]

I can't believe that actually worked. That's some real BOSC sciencing right there...

That was an ingenious idea Nick! I only have one question, who was holding the light bulb over your head when it came to you? LOL

 

[Ron R]

What is a foolproof way to ensure your microscope/camera is perfectly plumb over the apex of the blade so that your not introducing skew that screws up the exposure measurements?

This one has me stumped, especially with a miceoscope with less than 1 mm field of view. It's hard to be sure that you're perfectly plumb, but it has big implications for accuracy.

It's probably something obvious, but this has me stumped.

Here is a good example of why it matters. Here are two consecutive photos from a brilliant review of the Timeless Slim. Same razor, with the same blade, same photographer, 5 minutes apart. I added the red shave plane lines. The first obviously shows negative blade exposure. The second appears to show 0.15mm blade exposure. The listed blade exposure is 0.05mm. Obviously the first pic is bad, but you can see how bad the error can be in a worst case scenario. The second picture doesn't look that bad, but makes exposure measurements off by 300%.

Here is a pic of the Slim from Timeless website that clearly shows negative blade exposure on a razor listed with 0.05mm blade exposure!

Good illustration on skew, I have tried to eliminate skew also and what I try to do is level the razor as best as possible first on the USB Microscope base plate(1st objective). Then 2nd objective is locate the camera or USB microscope lens parallel to the razor end. When looking through the lens you should not see any distortion of the lengths on the head & only the end of the razor (take about 2 or 3 picture frames and pick the best one for reference). From your pictures you have illustrated you have done a reasonable excellent job of eliminating as much as possible the skew or unwanted parts of the razor to be shown. I have a stand with a base plate & different attachments for the end of the USB microscope that helps reduce skew also.
Another objective to my usb microscope when using it to fish out a ingrown hair is to put a reference mark on the outside of the USB microscope to let me know when the object was true to my hand movements. Nothing worse than moving a hand held microscope when it is not true to a movement of the arm.

 

[Dovo1695]

They look perfect to me. Well done!

If you have a photoshop program that allows you to use filters, you might find a filter, like a graduated polarized filter, to help with reflections.

This is an interesting idea. I don't have photoshop, but GIMP is free so it fits in my budget. I wonder it might have something like that.

 

[JPO]

Here is my setup. I am struggeling a little with the focus. The razor pushes aginst the glass and allignes it.

 

[kingfisher]

I got a gap of 0.39mm and an exposure of 0.15mm if recollection serves. Remember that the exposure is measured as a line perpendicular to the shave plane drawn from the shave plane to the apex of the blade. Gap seems like it should be straight forward but it's actually a bit confusing. I think it's a line perpendicular to the blade plane measured from the apex to the guard. The illustration is unclear, but perpendicular to the blade plane makes sense (I think).

It seems that there is some mislabeling in the illustration. What they have shown as "blade exposure" is definitely NOT what blade exposure means. Guard span is also incorrect, and looks to be almost random.
The photo is good. Maybe somebody could work on correcting the lines and labels.

 

[Dovo1695]

I just had an idea. Having the camera perfectly level doesn't really solve the problem of skew. The razor profile must be on exactly the same plane as camera. How can you be absolutely sure this is true? Have both things are on a +/- .0001 surface plate with machinist stands accurate to .0001 like the inimitable is a good start. Not cheap though.

There is a way to do it even on an uneven surface using nothing but a used piece of gum to level the razor. How? Put a small piece of mirror (2cm x 2cm on the razor! Then do the self leveling trick with the LEDs above. Now the camera and razor profile are level with one another +/- 0.5 degree regardless of what the stands are sitting on

You still haven't solved the problem of skew though. Having the camera on the same plane as the razor is half the battle but it doesn't do you any good if you're 4" to the left of the razor. You need the center of the camera over the center of the blade. To facilitate this, just drill a 1/16" hole in the center of your mirror. Use it a a sight hole and position it over apex of the blade before you start your optical leveling. When you start your leveling, the backlighting will shine up throught the hole and show up as a bright white dot that you will center between the 4 led circles on your camera display.

There you have it. Perfectly leveled, and deskewed.

 

[Esox]

To facilitate this, just drill a 1/16" hole in the center of your mirror. Use it a a sight hole and position it over apex of the blade before you start your optical leveling.

You've just described Aperture sight. Some of those sights are incredibly precise.

 

[Ron R]

Here is my setup. I am struggeling a little with the focus. The razor pushes aginst the glass and allignes it.
View attachment 1283969

I'm not into the USB microscoping as much as a few years ago, you fellows have a done a excellent job on the pictures and labeling and kind of envy you all for excellence. My scope came as a package with different attachments for the end of scope and with this ideal stand.
I just makeshift leveling the razors usually and they come out alright. I started with a regular garage sale microscope and those are primitive as compared to the USB types IMO.
The Andonstar 500 USB microscope might be a little outdated now??? but it works really well with the attachments for inspecting all kinds of things if into hobbies.
My eyes are not as good as when I was younger. I use my cell phone also with this unit also for inspecting. I have problems with getting JPEG pictures, my software converts it to something else and transferring is not easy and sometimes just take a picture of the screen to show something.

Just a quick set up showing how I usually try to observe razors(demo)

 

[Ron R]

That was an ingenious idea Nick! I only have one question, who was holding the light bulb over your head when it came to you? LOL

Nick could be a part time Genius .

 

[Dovo1695]

It seems that there is some mislabeling in the illustration. What they have shown as "blade exposure" is definitely NOT what blade exposure means. Guard span is also incorrect, and looks to be almost random.
The photo is good. Maybe somebody could work on correcting the lines and labels.

Both look right to me in the diagram. The definition of blade exposure below it does seem a bit unclear I'm often wrong about such things though.

Guard span is tough on that razor because the guard is pretty much in line with the shave plane so its hard to see where they intersect.

I'm probably missing something though. How would you change it?

 

[SCh5]

What if us ,as customers ,say
we had the power to ask every
razor manufacturer to
provide all the info we need ?

That would save us from all this
trouble .Reverse engineering using
digital photography has plenty of
caveats : the pics should be in RAW format ,low distortion Macro lens should be used,absolute near perfect leveling and
angling should be done and few more things have to be taken care of ...

We should demand that every razor
is accompanied with its “specification
data sheet “ .

 

[Dovo1695]

We should demand that every razor
is accompanied with its “specification
data sheet

That would be awesome. I think the best way to go about it is for enough of us to ask questions about exposure, guard span, etc every time we buy a razor. It will get annoying enough that they'll just publish the data sheets to avoid the expensive and time consuming nuisance of answering all the emails. I'll do my part to be as exasperating as possible; I have a natural gift for this according to my wife.