Sharpness Chart

[ToddS]

I was able to use oil immersion w/metallographic microscope for 1000x images, even able to angle the edge. Images at 400x not good enough to make out apex features but using depth of field one could estimate degree of bevel convexity and scratch depth. Plus the software allows for a range of various contrast enhancements.

And for a fact, stylus profilometers were used for sheer cutters and some forms of burst cut dies. You can't use them with most thin blades, but as the angle becomes less acute yes.

Spatial distortion is definitely an issue w/SEMs, better for studying morphology than assigning absolute measurement values, although methods of compensating are now pretty effective.

I'm not sure why I'm wasting my time here, but

I've seen your optical images.

I have two stylus profilometers, a Dektak I bought used about 20 years ago and a KLA Tencor P-7 that I bought new a few years ago. The resolution of these depends on the tip radius, which is typically 2-5 microns. The sell sharper tips, but they are a few thousand each - I have sharpened some myself with FIB and it is possible to reach 0.5 micron resolution, but the tip angle is very high and there is absolutely no way to scan the apex of a blade with one. The scanning probes that can achieve "better resolution than optical" are AFM (atomic force microscopes) and those tips are extraordinarily fragile and can ONLY be used on flat surfaces.

I don't know where you get your information about SEM, but it is just wrong. Any SEM built in the past 30+ years has a calibration routine done by the install technician that will provide better than 3% accuracy over the full range of conditions. When required for ISO9001, I check with my NIST calibrated MRS-3 standard and it's never been off by more than 1%.

 

[DeadboxHero]

Todd

Is the Hitachi TM1000 table top SEM useful for in house imagining? Or is it better to just pay the $200-300 per hour for specimens at a lab?

I'm not sure why I'm wasting my time here, but

I've seen your optical images.

I have two stylus profilometers, a Dektak I bought used about 20 years ago and a KLA Tencor P-7 that I bought new a few years ago. The resolution of these depends on the tip radius, which is typically 2-5 microns. The sell sharper tips, but they are a few thousand each - I have sharpened some myself with FIB and it is possible to reach 0.5 micron resolution, but the tip angle is very high and there is absolutely no way to scan the apex of a blade with one. The scanning probes that can achieve "better resolution than optical" are AFM (atomic force microscopes) and those tips are extraordinarily fragile and can ONLY be used on flat surfaces.

I don't know where you get your information about SEM, but it is just wrong. Any SEM built in the past 30+ years has a calibration routine done by the install technician that will provide better than 3% accuracy over the full range of conditions. When required for ISO9001, I check with my NIST calibrated MRS-3 standard and it's never been off by more than 1%.

 

[HeavyHanded]

I

I'm not sure why I'm wasting my time here, but

I've seen your optical images.

I have two stylus profilometers, a Dektak I bought used about 20 years ago and a KLA Tencor P-7 that I bought new a few years ago. The resolution of these depends on the tip radius, which is typically 2-5 microns. The sell sharper tips, but they are a few thousand each - I have sharpened some myself with FIB and it is possible to reach 0.5 micron resolution, but the tip angle is very high and there is absolutely no way to scan the apex of a blade with one. The scanning probes that can achieve "better resolution than optical" are AFM (atomic force microscopes) and those tips are extraordinarily fragile and can ONLY be used on flat surfaces.

I don't know where you get your information about SEM, but it is just wrong. Any SEM built in the past 30+ years has a calibration routine done by the install technician that will provide better than 3% accuracy over the full range of conditions. When required for ISO9001, I check with my NIST calibrated MRS-3 standard and it's never been off by more than 1%.

I don't own one myself, but was told this from an engineer who specialized in blade design through the '80s. A quick search leads to many contemporary hits re correction for SEM image distortion that may or may not have anything to do with this topic.

And again the profilometry statement came from the same engineer, whose scope of work covered a wide range of materials to be cut in the cleanest possible fashion. The specifics of much of this I was never privy to and therefore cannot speak to, but a wealth of information in general on the topic of blade geometry, grinding, finishing, measuring, testing. When speaking of higher resolution than an optical microscope may have been in context of detailed geometry leading into the edge and not just apex, but definitely talking about sub micron. Kodak had a lot of $ to spend on cutting science back in the 70s, and a lot to gain from incremental improvement. The man is passed now, so further clarification won't be forthcoming unfortunately.

And again, only so much can be learned from looking at an edge. Then you need a notebook and a material to be cut.

 

[ToddS]

Todd

Is the Hitachi TM1000 table top SEM useful for in house imagining? Or is it better to just pay the $200-300 per hour for specimens at a lab?

The appeal of these Fisher Price microscopes is rapid turnaround. They are fine for backscatter imaging of polished steel samples for characterizing grain structure, but they won't have the ability to resolve the apex of a sharpened blade. Better ones will also have an x-ray detector for elemental analysis. In my experience people use them for surveying samples to identify ones that are interesting or suitable for further analysis. If you are preparing the samples yourself, it shouldn't take more than 30 minutes for someone with a proper microscope to take a set of images. It would likely cost $10k/year to keep one running, so I don't see it as a cost saver unless you are looking at hundreds of samples per year. You would likely be better served with a high end optical microscope.

 

[DeadboxHero]

Master Todd


Thank you

The appeal of these Fisher Price microscopes is rapid turnaround. They are fine for backscatter imaging of polished steel samples for characterizing grain structure, but they won't have the ability to resolve the apex of a sharpened blade. Better ones will also have an x-ray detector for elemental analysis. In my experience people use them for surveying samples to identify ones that are interesting or suitable for further analysis. If you are preparing the samples yourself, it shouldn't take more than 30 minutes for someone with a proper microscope to take a set of images. It would likely cost $10k/year to keep one running, so I don't see it as a cost saver unless you are looking at hundreds of samples per year. You would likely be better served with a high end optical microscope.

 

[kreisler]

My Knife Deburring book

Just got the latest edition of your book, 6th edition 2021, Revised and Expanded, 84 pages (the 5th edition 2020 was 73 pages, while the free edition has 24 pages), thank you!

Best and most current book of its kind. Will there be a German language version of the ebook available too, one day in future?

 

[Blues]

wootzblade has left the building (of his own accord)...your ad will not bring him back. This thread is now closed.