Scrapmax blade flexing. How are they tested before release?

[PeterPHWS]

Umm yeah, I think I may need to get into computers

Youda man Peter, always taking your time to show us less savvy the light :thumbup:

You're welcome Eric and RWT :thumbup:

For those who are lucky enough to have scored an Elmax knife the cost of an Edge Pro to do the sharpening is going to look expensive ... double or treble the cost of the knife.
Lansky to a good enough system for a lot less. This is what I use and these are the important points to remember. The fixed holes that give angles in the "T" shaped clamp are not to be trusted. You need to do some accurate measurements and work with a scientific calculator which can be set on "degrees" and give you an "inverse tangent figure. The reason for doing this is that the thickness of each spine on a knife and the depth of their blade all vary ... so their is no "universal" 20 degree hole for all knives.

When you set up the knife in the clamp you need to measure the distance from the edge to the vertical T bar ... this gives you your adjacent distance.

Then you need to measure the distance from the middle of the spine to the hole which is most appropriate for your intended angle. In this case the 20 degree hole as marked on the T clamp.

This gives you your opposite distance. Then "opposite over adjacent" gives you the tangent. So once you have divided the relevant figures then press "inverse tangent" and this will give you the angle that the stone makes with the edge of the blade.

You can then alter the depth of the blade ( your adjacent figure ) by loosening the clamp and sliding the blade in or out to refine that distance for the perfect 20 degree angle.

Points to remember are that the clamp needs to be at the middle of the length of the blade or there abouts for a 4 inch blade. Going 2 inches either side of a central point will not radically alter the tangent figure in terms of the curved arc you make with the stone and rod when sharpening. Obviously where the belly of the knife is the distance is less and the the angle gets steeper as it curves round and reaches the point. There is no harm often in having a more robust angle towards the point as this keeps the strength of the point better by keeping plenty of metal behind the edge. If you clamp closer to the handle you can alter the angle on the belly and make this more steep ... the greater the adjacent distance is ... the steeper the angle. If you measure carefully the distances on the belly to the fulcrum point of the rod and stone you can alter the clamps position so that you control the angle of the stone at this point. I try and go for 20 degrees near the handle and all along the flat and let the angle increase on the belly to the tip to around 23 degrees. This depends ofcourse on the length of the blade and the steepness of the belly curve.

So long as you are not going too thin at the point all is well :thumbup:

Once settled on the right place to position the clamp keep a note book for each knife and measure off the distance from the end of the grip to where the clamp starts. This enables you to come back to sharpen the knife and line up the clamp perfectly for a repeat performance. Keep a note also of the adjacent distance which gives you the ideal 20 degree angle ( or whatever angle you want ).

You will find that by keeping these figures you can top up the edge on the knife very quickly. Your initial "reprofile" of the edge is also quite quick as there is very little metal to remove on these thin grinds. Going through the various grits of stone with the clamp in place and simply rotating the knife side to side gives you amazing consistancy ... which in turn when you come to use the finer stones lets you develop one hell of an edge. I guarantee you that you will be more than happy with this method ... because I always am.

Remember to coat the edge with a marker pen and use a magnification loop to see how the metal is being removed.

This lets you know during the reprofile that the stones have gone to the edge pinnacle consistantly throughout the whole edge. I say this because often by the handle/ricasso you need to take a little more metal off than elsewhere to give a uniform edge angle where the stones have fully taken the edge to a pinnacle.

Finally, as a tip for field sharpening ... buy yourself a packet of pipe cleaners ... take one of them and run it from the edge of the knife to the base of the T clamp and then bend it 90 degrees to go up to the hole the rod is going through with the stone. Mark this with a pen and then snip the pipe cleaner at this point and then fold the pipe cleaner so the 90 degree bend is kept as the fulcrum. Place this in your pouch where you keep a crock stick or sharpening stone for field touch ups. Once you need to use the stone or crock stick bring out the pipe cleaner and bend it back to 90 degrees with the adjacent side along the side of the blade. The height of the "opposite" side is then shown as a guide as to how high you need to hold the knife ( or crock stick depending upon whether you free hand with the knife or crock stick ) so that the angle it makes with the stone is the exact same as the one you used on your re-profiling job.

This might sound "heath robinson" but trust me it does work :thumbup: Free hand sharpening with a knife only 4 inches long is not hard to do on a small wet stone or crock stick ... but getting the angle to hold the knife at so that you are not "re-profiling the edge" in the field is the trick ... the more you replicate the angle already established ... the quicker your edge "top up" will be.

This gives you the confidence to approach the task without thinking that I am likely to make matters worse ... and after a few goes like this you're quite happy topping up a blade whilst out for a few days should you need to.

Hope this last point makes sense without a photo ... re-reading it the thing to remember is that if the stone is flat or the knife is held flat ( depending on using the knife to free hand with a stone or a croack stick to free hand with the knife held still ) the angle they make with each other needs to be replicated. Because when you are in the field you won't have the T Bar ... this distance is no good. You need to work with the distance which is the length of the side of the blade. So by running the pipe cleaner from the edge to the spine then bending it upwards at 90 degrees to see where it makes contact with the rod/stone when they are in place for sharpening ... this is where you mark off the pipe cleaner and then cut it. NOT at the T bar as advised above. The angle will be the same as a "ratio" but when it comes to sharpening in the field you need a "constant" that you can use. Place the longer part of the cleaner on the flat stone ... angle the shorter bit upwards to 90 degrees and from the tip of this you can place your knife to make contact with the stone so the spine is held at the height of the vertical bit sticking up. This means that the knife will contact the stone at the same angle that was used on the Lansky system if the edge is positioned on the stone so that it makes contact where the other tip of the pipe cleaner is.

Anyway ... let me know if this is clear or is clear as mud ...

 

[chiral.grolim]

...You need to do some accurate measurements...

Remember to coat the edge with a marker pen and use a magnification loop to see how the metal is being removed.

Finally, as a tip for field sharpening...

Wow, that was quite detailed. May I ask, how important is it to users to know what angle their knife is sharpened at?

I have a quick alternative which I use with my DMT Aligner set, similar to the Lansky set. Tools required: protractor, indelible marker (preferably Red or another bright color), aligner kit, knife.

1) 'Paint' the entire edge bevel of your knife with indelible marker (as you mentioned)
2) Clamp knife into device and set rod-apparatus such that the hone contacts the knife edge at an angle approximating your desired bevel angle (esp. if reprofiling). Use a protractor to show what the set apex angle is at various locations along the blade edge (as the hone-arm swings from the clamp), and decide whether you are satisfied with this angle or not. Adjust hone angle or clamp position as desired.
3) Once your angle is set, lightly run the x-fine hone along the entire edge of the blade - the idea is to see where the hone is contacting the edge via removal of 'paint' with minimal removal of metal. If 'paint' is removed along the shoulder but not the edge, your set angle is more acute than the knife's angle and you'll want to either adjust the angle setting of the device or start with a coarse stone to reprofile the edge. If 'paint' is removed from only the edge, your set angle is more obtuse than the knife's angle and you'll want to either adjust the angle setting of the device or use a fine stone for the minimal metal that you'll be removing. If the location/amount of paint removed on the initial swipe varies along the edge, this indicates a difference in the geometry of the knife's bevel and the manner in which the device sharpens it. You can reprofile from the position you have the clamp set or move it to another position along the blade length, etc. Whichever choice you make, make a note of where you locate the clamp and try to be consistent about clamp placement each time you resharpen on the device.
4) Proceed with sharpening at desired coarseness, noting progress and consistency via removal of the edge 'paint' (which you can reapply as desired).

The DMT Aligner Kit is easy to carry into the field. But if you are confident enough to freehand, V-bevel or convex, all you need to keep a consistent angle is that indelible marker. Simply 'paint' the edge, place your hone at the approximate angle, and make a light pass. Adjust your angle as needed based on the removal of the paint, and work until you've achieved the desired level of polish.

 

[2TONYB]

Wow! A lot of good info above.

 

[PeterPHWS]

The difference between your post and mine is that yours is dependant upon retaining the angles set by the maker ...

Using a marker pen to determine where the stone makes contact with the edge and then altering the contact point to bring the contact to the pinnacle so that it replicates what has already been established .... then fine .... that works ...

If you want to alter the angle and re-profile the blade then your dependant upon your use of a protractor ... when you say ... decide what angles you want to set by use of a protractor you have'nt explained how difficult or easy that is to do ... and what happens in my experience is that the tolerance level you can be out by if you are free handling the protractor can be noticeable ...

When I say noticeable ... I mean in terms of the time taken to restore the edge ... you only have to be out by a degree or more ... say two ... and if you have put a fine stone on your DMT kit ... which functions very similar to the Lansky ... removing that amount of metal on a blade hardened to the Rc 62-64 range will take a long time ... probably you will realise that you need another stone ... a much coarser stone for the task ... but if you deal with the reprofile by distance measurements and tangents this will give you an angle management that can go into tenths of a degree if need be ... naturally you don't need that but my point is that it is much more precise ...

The more precision you have then the more you replicate accurately and the quicker it takes for a top up sharpening ...

If however, you want to consider why it is helpful to know pricisely what angle you are profiling to ... as opposed to plus or minus a few degrees ... the answer is in terms of benefit ... still firstly one of "time" on life time management of the edge ... but after that the benefits are less noticeable in terms of performance ...

I am not going to say I can tell the performance difference between a knife sharpened at 20 degrees and at 22 or 18 degrees ... but I can say that restoring a razor edge to a knife based on attaining an accurate reproduction of the original edge and being out by 2 degrees is probably in the region of 30 minutes ... it depends ofcourse upon the grit of stones you commence the task with ...

Span these sort of variables over the life of the knife and you might well find that the 0.10 behind the edge for ease of cutting is quickly becoming 0.20 and then 0.30 as you have to remove more steel and progress up the gradual taper of the knife. This is important with thin grind knives to which these techniques are being discussed. the thicker the knife becomes the less the advantage the geometry begins to play ...

All told though ... I suspect that the geometry changes would need to be significant to appreciate them ... spanned over a gradual deterioration and I doubt it would be easy to notice ...

So at the end of the day my best point for making a case as to why to sharpen a knife where you know the exact angle ... is why not ? If it enables a quicker restoration of the edge and prolongs the thinness of the geometry ... at little cost save that of a bit of time the first time you do it ... then after that the situation is "win win" ... in my view you might as well go the route of "precision" than the route of "close to precision" ...

Other "up beat" benefits though which are often significant are the removal of the lack of confidence that many have in thinking they don't know exactly what they are doing in sharpening ... when you can show that it can be done "exactly" and they see the benefits themselves from the edges they get ... it is often a "watershead moment" for many ...

I have to say though that I have not sharpened by your method and compared it directly to mine ... both are probably a good option ... I went my way because I knew it would be precise and because I knew I would have enough lack of precision "in the field" if using my methods which born out of a desire to travel light and reliably in the field I find are better.

Do a river crossing with marker pens brought along for the field kit and damage them ... then where do you go ? Field solutions for me need to be able to withstand a lot of hazards ... as well as last indefinately ... pens run out of ink but also seem to stop working long before you expect them to.

Your mileage may vary on stuff like this ... each to their own ... ultimately having the ability to sharpen the knife well is the main thing.:thumbup:

 

[chiral.grolim]

The difference between your post and mine is that yours is dependant upon retaining the angles set by the maker ...
Using a marker pen to determine where the stone makes contact with the edge and then altering the contact point to bring the contact to the pinnacle so that it replicates what has already been established .... then fine .... that works ...
If you want to alter the angle and re-profile the blade then your dependant upon your use of a protractor ... you have'nt explained how difficult or easy that is to do ... and what happens in my experience is that the tolerance level you can be out by if you are free handling the protractor can be noticeable ... in terms of the time taken to restore the edge ... you only have to be out by a degree or more ... say two ... and if you have put a fine stone on your DMT kit ... removing that amount of metal on a blade hardened to the Rc 62-64 range will take a long time ... The more precision you have then the more you replicate accurately and the quicker it takes for a top up sharpening ...

This method isn't dependent on the maker's angle at all, it's dependent on how satisfied you are with your knife edge as is and what you'd like it to be, same as your method The only difference is precision of measurements. Please remember that the protractor's only purpose is to tell you what the current bevel angle is in case you want to know. It is NOT a guide, it should not be used for precision purposes any more than your pipe-cleaners as both give a false sense of precision, esp. given changes in the blade width with edge degradation. The protractor is VERY easy to use (much easier than your alternative), simply line-up the edge+hone apex with the apex point on the protractor and read the angle measurement, no other measurements of calculations involved. Using the marker to tell you where the hone is making contact tells you immediately how much work there is to be done and thus informs which coarseness of stone to use. One quick measurement which is entirely optional (i.e. not necessary, just for edification), one paint-check, and you're in business - that's a LOT of time saved and no extra effort involved :thumbup:

If however, you want to consider why it is helpful to know pricisely what angle you are profiling to ... the benefits are less noticeable in terms of performance ...

... it depends ofcourse upon the grit of stones you commence the task with ...

... I suspect that the geometry changes would need to be significant to appreciate them ... spanned over a gradual deterioration and I doubt it would be easy to notice ...

:thumbup: :thumbup: :thumbup:

So at the end of the day my best point for making a case as to why to sharpen a knife where you know the exact angle ... is why not ? If it enables a quicker restoration of the edge and prolongs the thinness of the geometry ... ... in my view you might as well go the route of "precision" than the route of "close to precision" ...

But your precision is an illusion, takes longer, and doesn't prolong the thinness of the geometry any more than simply using the marker and always sharpening away the back shoulder of the bevel. Both aligner kits have slot-restrictions on edge angle anyway, so these minute adjustments can only be made a certain (equal) amount regardless of the precision of your measurements. *shrug*

Other "up beat" benefits though which are often significant are the removal of the lack of confidence that many have in thinking they don't know exactly what they are doing in sharpening ... when you can show that it can be done "exactly" and they see the benefits themselves from the edges they get ... it is often a "watershead moment" for many ...

I have to say though that I have not sharpened by your method and compared it directly to mine ... both are probably a good option ... I went my way because I knew it would be precise and because I knew I would have enough lack of precision "in the field" if using my methods which born out of a desire to travel light and reliably in the field I find are better.

For me, that "watershed moment" was using the marker and thereby seeing that I was making progress or seeing where I was messing up. I'd tried using perfect precision before but until I had that visual aid, I was continually frustrated. Once I employed the marker, I dropped the measurements realizing that i didn't need to know, and certainly not with such precision, what the edge-angle was, only where i was sharpening in relation to it, and that translated to the field as well. Now, the aligner kit is simply for quick restoration/reprofiling as it relieves me of holding the proper angle myself and lets me move my hone more quickly, shortening sharpening time. For touch-ups and in the field, I can free-hand with the same consistency but more freedom than the kit but it takes longer as i don't move the hone as quickly. Whether the kit holds the angle or I do, what matters is how the paint is being removed as that is the indicator of both the sharpening angle and of my progress.

Do a river crossing with marker pens brought along for the field kit and damage them ... then where do you go ? Field solutions for me need to be able to withstand a lot of hazards ... as well as last indefinately ... pens run out of ink but also seem to stop working long before you expect them to.

Lots of equipment can fail in the field - what if your pipe-cleaner breaks or you forget which arm is vertical? Come to think of it, why even have a horizontal arm? The blade-width shouldn't change much in the field, all your method desires is a guide of how far from center-spine to angle the hone... And a pipe-cleaner is pretty easy to lose and again is not really a precise measuring tool any more than a bit of string, stick, or a visual estimation are, and none are direct indicators of your progress... *shrug*

Your mileage may vary on stuff like this ... each to their own ... ultimately having the ability to sharpen the knife well is the main thing.:thumbup:

:thumbup: Totally agree.

 

[PeterPHWS]

Some interesting points there ... the one I like the most is the reference to "field" use of the marker and the initial swipe giving you a good indication of the work involved in the field ... albeit the set up is done with a protractor to give an indication of angle ... I will get a protractor and a marker and see how this goes in the field ... I agree it could be a fair bit more accurate than a pipe cleaner :thumbup:

Seeing where the first swipe took away ink would also let you know how close you were to the original profile ... I agree on that ... so yes ... there are some advantages there :thumbup:

It is always good to learn more ...

 

[sam.t]

Great thread, I am picking up technique and tricks here. Thanks.