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All Things Handles
Forum: Knife Making & Bladesmithing
Last Post: grepper
1 hour ago
» Replies: 15
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Swedish wood carving knif...
Forum: Woodworking Tools
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12-05-2018, 10:57 PM
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TORMEK PA-70 is great hon...
Forum: Relevant General Discussion
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Articles on Factors that ...
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Last Post: EOU
11-30-2018, 04:11 PM
» Replies: 5
» Views: 151
[Video] Scotch Brite whee...
Forum: Relevant General Discussion
Last Post: Mark Reich
11-24-2018, 03:04 PM
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Platen Kalamazoo SM1 1x42...
Forum: Relevant General Discussion
Last Post: Mark Reich
11-24-2018, 02:55 PM
» Replies: 4
» Views: 135
PT50s With a bit of wobbl...
Forum: Relevant General Discussion
Last Post: SHARPCO
11-20-2018, 04:40 PM
» Replies: 3
» Views: 107
Wearing of ceramic glass ...
Forum: Relevant General Discussion
Last Post: SHARPCO
11-20-2018, 04:01 PM
» Replies: 16
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Sparks when grinding hard...
Forum: Edge Sharpness Testing
Last Post: EOU
11-20-2018, 10:20 AM
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» Views: 120
Can beauty scissors be sh...
Forum: All About Edges
Last Post: grepper
11-19-2018, 09:25 PM
» Replies: 3
» Views: 91

 
  Articles on Factors that Control Edge Retention
Posted by: Larrin - 11-26-2018, 11:21 AM - Forum: Relevant General Discussion - Replies (5)

I wrote two very long articles on what factors control edge retention of knives. That includes the steel, hardness, and edge geometry. I had to analyze a huge database of CATRA tests from a major knife manufacturer. There were a lot of questions answered and it's too much to summarize here. I hope you like the two articles:
https://knifesteelnerds.com/2018/11/19/s...retention/
https://knifesteelnerds.com/2018/11/26/s...etention2/

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  [Video] Scotch Brite wheel
Posted by: SHARPCO - 11-21-2018, 04:22 AM - Forum: Relevant General Discussion - Replies (1)

I use Scotch Brite belt for surface conditioning and I satisfy with that. 

And I found this Youtube video. 



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  Platen Kalamazoo SM1 1x42 Platen
Posted by: Mark Reich - 11-20-2018, 11:58 AM - Forum: Relevant General Discussion - Replies (4)

This is The Original Kalamazoo Platen Mod I've been making for over a decade. I have had no competition or suggested improvements I'm aware of. Kalamazoo Industries copied this pattern, and briefly offered them for sale. Shortly thereafter I stopped modifying their platen in favor of the much stronger design that has remained unchanged since 2010. 

This is the most complete compilation of pictures, including the manner of adjust-ability that makes this a true "one size fits all" solution.

 [Image: uNVcLCn.jpg] [Image: fbhoPML.jpg]
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  Inconsistent Results
Posted by: Mike Brubacher - 11-19-2018, 04:46 PM - Forum: Edge Sharpness Testing - No Replies

Recently three posts, in a new thread, were made to the BESS Exchange describing a wide range of problems experienced by three of our customers. These issues included old and new style ATFs whose results didn't match, PT50As that did not match the results of PT50Bs, DE razor blades that yielded abnormally low readings etc.. The original thread was taken down due to inappropriate posts made by some of our Exchange members. Those three original posts are copied in their entirety at the bottom of this post. The posts made by  other Exchange members as follow up to the three original posts are not included.
 
We promised to look into these claims for these three customers and have done so.  We have been in communication with one of the posters and cleared a couple of reported problems (i.e. PT50A/B discrepancies) up in so doing. We spent part of last week and this weekend looking into the balance. We believe, with a great deal of confidence, that we now understand the problem. 

The root problem for all these reports lies with the new ATF-10G. The ATF-10G utilizes a plastic clamping nut on a steel stud to provide compressive force in locking the test media down. Only a very moderate amount of rotational force is required to accomplish this. A plastic nut is utilized in this application so that the finish of the test media seat is preserved. Only by tightening this nut well beyond the requirement were we able to begin duplicating some of the more extreme findings of our three customers. The problem has it's roots in the plastic threads of the clamping nut. These threads will "give" allowing the user to keep tightening and rotating the nut thereby applying more and more tension to the test media. In fact, taken to extreme, the test media can be permanently damaged in this effort.
 
We do acknowledge that the perfect "window" for tensioning is not as large as we would like.  We identified two very simple fixes to greatly enlarge this window; (1) We have inserted a simple flat washer into the scheme that acts like a bearing between test media and nut. In this system the plastic nut spins on the washer as opposed to the test media.(2) A nut with metal threads prevents the over rotation of the nut. We are sourcing  plastic nuts with metal thread inserts.
 
All new instruments are being shipped with new instructions and washers in place on the ATF-10G. Use of the washers is optional for users. Once we receive our new plastic nuts with metal thread inserts we will test to see if it is an even simpler fix or, possibly, used in addition to the new washer. These are the only three complaints we have received to date regarding tensioning difficulties but one never knows, there could be some who are suffering in silence. If so, let us know via email and we will send a washer (M4 flat washer). In the future, we ask that customer service questions of this nature be submitted directly to us via email. If something of universal and general interest arises out of the solution, we will post it to the Exchange.
 
Here are the new instructions that accompany all new units that utilize the ATF-10G.

                                 
 
 
 
 
 ATF-10G supplemental instructions. Your ATF-10G includes a washer that acts as a bearing between test media and the beveled seating surface of your ATF-10G. This arrangement prevents accidental over tensioning and potential damage to the test media during the clamping process. Over tensioning can occur when the plastic nut is intentionally tightened well beyond the point necessary to secure the test media. Over-tensioning results in artificially low (10-20 pt.) BESS scores.To re-run test media; loosen the plastic feed screw a full turn and then pull/feed-out the necessary amount (approximately 2.5 inches, 65mm) of test media. Snug the plastic feed screw back down. Crack the clamping nut open allowing enough room for the test media to pass between washer and fixture bevel. With one hand, grasp end of test media and "slide' test media under washer until test media drops into slot. Pull all the slack out of the test media gently (no remaining hump or dip across the measurement gap of the ATF) and then tighten clamping nut moderately. Now you're ready to take your next edge measurement
 
Here are the original three posts in their entirety:
 
Hi all. 

So I'm in the unique position to have both a PT50B and a PT50A.

Straight away I noticed inconsistent results between the two units. 

Long to short I'm seeing around a 30% increase in the scores on the ATF10G (with the nut) I've chewed up about a mile of test line this weekend trying to get consistent results. 

Seems the newer ATF10G line holder is very variable depending on line tension. Another note is that the older ATF line holder has a "bolt" style line lock. The ATF10G is a "nut" arrangement. The bolt style on the ATF definitely adds an element of line tension as the rotation tightening pulls on the cord. This seems quite consistent with the tension on the side of the ATF. 

So I tried the bolt arrangement on in the ATF10G clamp and got very varied results (like as low as 10 BESS up to 46 BESS on a newly sharpened kitchen knife). Consistent scores of around 30 with the ATF holder. (knife scored 77 on a clip) 

Some of you will know I've been using my PT50B in edge testing on YouTube. The change in results will render my testing over. I can't make the call on under 160 BESS being "shaving sharp" with the ATF10G. 

I had one knife that scored a consistent 100 bess in the ATF, edge was easily popping arm hairs off. With the ATF10G I was scoring over 160 BESS. No way it was over that golden number. (clips scored 155 & 156).

Is anyone else seeing results this varied or am I unique having two different units. 

I was really hopefully the BESS measurement was a consistent thing but it seems not.

 
 
 
 
NJMS and I , as well as a couple other sharpness nerds have been discussing our inconsistencies extensively, trying to figure out how all our results could vary so much. The tiniest fraction of difference was between spools, the big difference is certainly the fixtures. I spent months pulling my hair out (literally) trying to figure out why I couldn't match their scores, whilst being able to achieve the same sharpness feats as them. I would have an edge that treetops the hair off my arms and legs, would sever my hair on contact, (in the hanging hair test it would be a HHT4 or HHT5) yet would score 70-80 on my tester with the 45 degree fixture. I have no doubt in my mind that if I added tension to replicate what happens when tightening the old fixture, it would have been scoring sub 40. 

We came to the conclusion there was definitely something wrong when I demonstrated to the group, a 200+ bess edge whittling hair and popping the hair off my arms. We found minor discrepancies on older vs newer spools, thats no big deal, turns out we never checked the fixtures until today. 

Using my razor, I can score 5 Bess by adding more tension to the filament, If I have it so its just a bit tighter than slack, that number raised to 25, having very slight slack raises it to 55. 

The only way I can see making the fixtures absolutely dead accurate is to have a screw with a hole in it that you feed the string through loosely, and a knov that only tightens to a certain amount of torque before spinning and not tightening the string anymore. Problem is that would use a lot of filament.

 
 
New member here, and fairly new sharpener. I'm one of the sharpness nerds mentioned by rs-Travis. While I don't yet have the skill or experience of rs-Travis or NJMS, I have had similar results. I've had hair-whittling edges in the 170s and above (227 on the clips and whittles hair). So I ran a series of tests on my PT50A and found two trends.

1) One test was for various degrees of media tension on the ATF10, using a Dorco DE blade.
I found that looser media produced a higher number. Using the subjectively-felt tension in the clips as a baseline, I found that higher tension on the ATF10 yields lower numbers. Stretching it very tightly yielded a 14, whereas stringing it more loosely than the clips's tension gave me a 64. The clip itself yielded a 56.

2) Another test was comparing the ATF10 to the ATF10G on a series of 10 knives, with the same canister of media, at fairly constant tight tension.
I found that the ATF10 yields consistently lower numbers than the ATF10G. For example, a Spyderco PM2 scored 42 (ATF10) and 73 (ATF10G). A Victorinox scored 144 (ATF10) and 189 (ATF10G). I wonder if this is because the thumb-screw on the ATF10 adds tension to the media as it tightens down to secure the media?

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  PT50s With a bit of wobble
Posted by: EOU - 11-19-2018, 11:26 AM - Forum: Relevant General Discussion - Replies (3)

We've received a few reports, usually regarding instruments that are shipped overseas, of PT50 Series instruments that have just a tiny bit of wobble in the bases. The wobble manifests always in the front left corner of the instrument. A very few units seem to take on this set during shipping. We know this because they are checked for this characteristic prior to packaging. The actual error in the base averages about .006" (.15mm) on the offending units so very slight indeed.

Four-point contact bases are just problematic. If the surface they are rested on isn't perfectly level, they're going to wobble and if the contact points aren't precisely even, same result. Three-point contact bases don't suffer from this problem. We've begun adding two additional contact points toward the center front of all units. This creates a sort of pseudo three-point contact base for our instruments because the added contact feet are .010" higher (thicker) than the original front pads on either side. This will steady the instrument on surfaces with some variation in level as well as take care of any "set" problems that may have occurred during shipping. The new pads are adhesive back, .0625" (1.6mm) thick. Here's a picture of the improvement that is now part of all new PT50 model instruments;

                                                                         

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  Can beauty scissors be sharpened with a belt grinder?
Posted by: SHARPCO - 11-18-2018, 03:12 PM - Forum: All About Edges - Replies (3)

As you know beauty scissors has convex edge.  So to sharpen it, we need WOLFF Hira-To or TAS(& convexing clamp). 

But belt grinder(e.g. Viel, Kally) can sharpen convex edge knives. 

How do you think about it? Is there any problem with sharpening beauty scissors with belt grinder?

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  TORMEK PA-70 is great honing compound
Posted by: SHARPCO - 11-18-2018, 02:59 PM - Forum: Relevant General Discussion - Replies (7)

I use TORMEK PA-70 honing compound not only with tormek leather honing wheel but also leather belt on the VIEL S5. It's great for deburring & honing. 

But I wonder if I can use it with another type wheel(e.g. felt wheel) at high speed(about 1745 RPM). 

Has anyone tested this here?



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  Sparks when grinding hard carbon steel
Posted by: grepper - 11-16-2018, 11:53 PM - Forum: Edge Sharpness Testing - Replies (5)

Please understand that, not being a chemist or metallurgist, I’m speaking out of my expertise and this is just my attempt to explain what is happening here.  I would more than welcome and hopefully someone here can offer edification, clarification or refutation.
 
In this post, http://bessex.com/forum/showthread.php?t...03#pid4203 Mr. Mark spoke of creating a lot of sparks when grinding hard carbon steel.  I responded in a following post by stating that I have never encountered sparking during basic sharpening with a Kally.  Mr. Mark then suggested that I try the tip of a file.  I did, and indeed, even the lightest grinding produced glowing sparks much like burning a sparkler.  Even just barely touching the file to the 150 grit Cubitron belt created sparks.  It’s rather remarkable.  So much so that it seemed that if only one abrasive particle on the belt touched the file a corresponding spark was produced.  Try it.  You’ll like it!
 
So, what’s gong on here?  It would be logical to assume that there must be something about the steel that increases friction so dramatically as to generate enough heat to melt steel to the point of glowing red hot with even the most minor and ephemeral contact with abrasives.  That makes sense, but I think that explanation is erroneous and there is another cause of the sparking.
 
Oddly, very fine particles of iron are pyrophoric.  Pyrophoric materials spontaneously ignite when exposed to oxygen rich environments such as air, due to heat generation caused by extremely rapid exothermic oxidation.
 
I’m sure many of us have witnessed flash rusting of freshly ground iron.  They don’t call it flash rusting for nothing!  Rust starts to form almost instantly if the material is not protected.  In this case, as soon as flash rusting starts it slows dramatically because the instantaneous coating of rust (oxidation) isolates the surface from exposure to oxygen in the surrounding environment.
 
Grinding during sharpening produces extremely small iron particles.  When grinding, not only is the protective layer of oxidation stripped from the outer surface of the blade by the abrasive, but when particles are torn from the edge the freshly exposed “underside” of these particles, also not protected by a layer of oxidation, is exposed.  This creates the maximum surface area relative to the particle size possible that is available for oxidation.  Even the small additional heat generated by grinding facilitates the oxidation process and the particles burn in the air.

So, I did some searching around and found a pretty good explanation of what I think is going on:
https://www.amazingrust.com/Experiments/...ic_Fe.html

I always found it odd that iron and steel can actually burn.  My first exposure to this was when I was a kid with a chemistry set.  I remember being surprised to see iron filings burn when sprinkled into the flame of an alcohol burner, and equally fascinated to find out how easily steel wool can be ignited with a lighter.  I guess I shouldn’t have been considering I loved setting strips of magnesium on fire.  I highly recommend igniting magnesium as entertainment for kids.  Hours of fun there!  Oddly I still have all my fingers and vision in both eyes.

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  Wearing of ceramic glass platen
Posted by: SHARPCO - 11-13-2018, 07:57 PM - Forum: Relevant General Discussion - Replies (16)

   

This is ROBAX glass(heat resistant ceramic like pyroceram) on my Viel platen. I thought it was very hard and hardly worn out. But it has worn like this in a few months.

I know there are people who use pyroceram here. How much wear is your glass?

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  Efficiency of ATF-10G
Posted by: SHARPCO - 11-11-2018, 01:58 AM - Forum: Edge Sharpness Testing - Replies (1)

I wanted to know exactly how much less media ATF-10G consumes. Media consumed by ATF-10 and ATF-10G are 55mm and 35mm respectively. i.e. ATF-10G consumed 36% less. I did my best to save media.

Great job.



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