Scrapmax blade flexing. How are they tested before release?

R

RWT

Joined
Mar 15, 2011
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Curious what type of testing any of the three shops do before releasing a model. I was fortuante enough to pick up a Scrapmax and love how well it cuts. This weekend we cooked up the chuckar and quali we shot on a trip earlier in the year. While cutting the breast from the chuckar I noticed the Scrapmax blade flexed similar to a fillet knife. I was slighlty concered as the blade is as thick as a few mora's I own and those blades do not seem to flex under the same strain. I know the warranty will cover me if something happens. However, I am curious to know what testing requirements the companies put a blade through before release. For instance do they have a minimum # of cuts on a rope once they are sharpened to a specific degree per side or lateral stress/bend test at 1" from tip to so many degrees and return to true?

I know the hockey masked guy beats them to pieces and I have read and trust in few forms of documentation provided by Jerry I have found on the forum. I am more interested in specific repeatable standard testing before a blade is released. Any info is appreciated.
 
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Although this belongs on the Scrap Yard forum, where my drunken brother Dan could field it, I will point out a few points to consider.


The Scrapmax blades have a full-height flat ground bevel, whereas Mora style blades have MUCH shorter bevels that leave nearly 60 - 80% of the blade at full thickness. So, the Scrapmax blades are going to have a MUCH better slicing geometry than a Mora and are designed primarily, for slicing only. . . and at that. . . . they will excel ! ! !

If you beat on a Scrapmax blade with a hammer, it will most likely suffer a catastrophic failure. Lateral stress will likewise cause a lot of flexing, just like a filet knife. These are NOT heavy duty beaters . . . If you treat them like most of the other Scrap Yard models are meant to be treated. . . . they will die!!! . . .

So. . . .. "Slice Slice Baby. . . deh deh deh. . . . deh deh deh" (Sung to the tune of Ice Ice Baby!)

Let's Drink!!! :thumbup:

Jerry:D
 
Its worth pointing out that a full flat grind removes 50% of the stock material, quite a weight saver. I need a Scrapmax now.
 
I didn't realize the grind had that much to do with it. I got this one to try out on cleaning deer and hogs so it won't see any real abuse. I love the weight and know...have to go daughter just hit the potty for first time. Time to celebrate.
 
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Yep...it's a cutter! :thumbup:

051.jpg
 
the scrap max is definitely a slicer, it may even displace the weinerdog as my goto kitchen knife.

also RPN, I have a dish exactly like that one, small world
 
Jerry Busse said:
Although this belongs on the Scrap Yard forum, where my drunken brother Dan could field it, I will point out a few points to consider.


The Scrapmax blades have a full-height flat ground bevel, whereas Mora style blades have MUCH shorter bevels that leave nearly 60 - 80% of the blade at full thickness. So, the Scrapmax blades are going to have a MUCH better slicing geometry than a Mora and are designed primarily, for slicing only. . . and at that. . . . they will excel ! ! !

If you beat on a Scrapmax blade with a hammer, it will most likely suffer a catastrophic failure. Lateral stress will likewise cause a lot of flexing, just like a filet knife. These are NOT heavy duty beaters . . . If you treat them like most of the other Scrap Yard models are meant to be treated. . . . they will die!!! . . .

So. . . .. "Slice Slice Baby. . . deh deh deh. . . . deh deh deh" (Sung to the tune of Ice Ice Baby!)

Let's Drink!!! :thumbup:

Jerry:D
Click to expand...


Now that's funny. :D

And all true..

When using thin ground blades keeping the spine inline with the edge is good practice and in doing so one can do some harder cutting also.
 
Take it easy on the scrap max and use it for all the slicing and fine cutting jobs you have.

Then pull out a Busse for when you need to put some serious strain on a blade!
 
The Scrapmax is an interesting development in the Bussekin range :thumbup: I know all that were done were sold at Blade but I believe Dan still has more Elmax available to do more knives ... these type of knives have limitations IMO that are far , far , less than their advantages. Or, spinning it around and adding some detail to my views, after a year of using a similar style knife from Phil Wilson the geometry advantages of the thinner blades for cutting in the kitchen and in the field ... such as field food prep and wood work for both fire and impliments ... these type of knives have a much longer "use time" with their edge.

Think of a cheap kitchen knife which is quite dull but still prepares food without difficulty ... it is the geometry working for you here ... combine this with a good HT and edge retention and this type of knife works in the field SO much better ... they "demand" good technique ... but as a knife "user" there is a pride to be found in developing this ... you basically are working with the advantages and mitigating the limitations ... but the performance and capability of these knives goes well beyond the capabilities of the traditional thicker "field" knives in the 4" to 5" range if you work "with them".

Somewhere in the art of knife making lies the understanding of "geometry" ... and balancing this with "intended use" ... for me my Basic 9 is just about "perfect" for a light weight, forward balanced "field knife" with chopping capability. It has a great edge design which enables easy sharpening and a long enough blade to enable batoning the largest of logs. If sharp enough it can zip through wood prep for fires and carving for traps. The resistance to the blade however is an issue but manageable if the edge is really sharp because the taper from the .25 spine is very good. It does'nt however excel at this. Here lies the oppertunity of carrying a smaller knife more suited to these tasks and when considering what works best in such a partnering arrangement ... I am now enjoying the use of a thin geometry knife.:thumbup:

It will be very interesting to see what Dan does with the Elmax steel he has got on hand ... steels able to take a high Rc temper for edge holding and be sharpened on a more robust than you might expect angle ( 20 degrees either side ) but with a thin geometry so they feel like they are cutting with a 15 degree either side edge because of the lack of resistance to the cut from the thin blade ... yet avoiding the "roll" of the edge which usually accompanies such thinner angles ... a 20 degree either side edge on a thin slicer seems to achieve that legendary "edge retention" which people search for in knife selection. :thumbup:

I am still on a learning curve with this type of knife ... but I expect when I finish my ideal trio of blades will be something in this style with my Basic 9 for a field knife and for heavier work my Nuclear Zilla. I am looking forward to seeing what Jerry or Dan produce :cool:
 
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So not knowing enough to know better, am I screwing up the blade by putting a convex edge on it with my worksharp? This is where I would like to sit down with someone knowledgable about geometry and edges over a case of beer and learn what to do. Anyone know the bar Jerry hangs out in?

Is this type of blade better with a v grind edge?
 
I would stick with a V type edge on those blades. You can put them on at a very precise angle using any of the sharpening systems like edge pro or lansky ... this makes a difference IMO from working with the edge on my knife because when you go to a steeper angle the steel at the pinnacle of the edge can roll ... bring it down a little and you avoid this when applying diagonal force such as when pointing sticks ... the edge therefore gets the chance to be worn away as opposed to being rolled away ... the higher Rc HT therefore gets the chance to work in your favour as the edge being harder lasts longer.

If you want to convex it a little after applying the V edge just do a bit of stropping on an angle steeper than the edge was applied. By "steeper" I mean if the edge was applied at 20 degrees either side ... then strop at a 15 degree angle ... if using compound this will curve the shoulder angle into a convex shape but the "pinnacle" will still be able to be a precise 20 degrees.

Spyderco did a lot of testing when designing their Sharpmaker as to what were the optimum angles for their blades. They found that a 20 degree main edge and a 15 degree back bevel seemed to give the best combination of longevity and sharpness. After a fair bit of experimenting I am inclined to agree ( pun intended :D ).

I know a lot of guys who test edges seem to take them to the steeper angles of 15 degrees and even steeper down to 10 degrees ... but to benefit from these sort of angles you need to cut vertically with the spine above the edge ... this eliminates the torque which can cause "rolling" and works for rope cutting and cardboard cutting. However, when it comes to doing feather sticks with wood or sharpening a stick for a tarp peg etc ... you need to cut diagonally into the wood ... hence the benfit for a field edge of not going as steep and giving the edge a chance to wear away ... as opposed to rolling.

When barber's use a cut throat razor and you see them stropping the blade ... this is to centralise the edge because when shaving you also have to cut at a diagonal ... the same principals apply here ... go too steep and you will need to keep stropping the edge in the field to bring it back into alignment ...

A convex edge may well be stronger than a V edge ... but if you don't know precisely the angle you are going for ... you run the risk of going too thin. So for me I do my thin knives as a V grind and then might convex the shoulder. To be honest though when the edge is as thin a profile as on these type of knives the need to round the shoulder is a lot less. Personally I would leave the knife at a V grind.

Hope this helps.
 
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Once they get that thin behind the edge and we are talking in the .010" and less range here it's recommended to stay with a V edge as stated above because one is going to knock the corners off anyway when stropping.

DON'T use power equipment on blades that are ground that thin, all that will happen is you will burn up the blade if one isn't extremely careful and or doesn't have a really good grinder that can be adjusted very slow almost zero belt speed.

Blades that are that thin are VERY easy to sharpen free hand and touch up because there isn't much metal behind that edge.

I have 4 Phil Wilson Customs myself, the thinnest I own is .006" and tested another that was .005" behind the edge.
 
RWT said:
So not knowing enough to know better, am I screwing up the blade by putting a convex edge on it with my worksharp?...

Is this type of blade better with a v grind edge?
Click to expand...
Like those above said so well, you can convex the edge or just V-sharpen and then knock off the bevel-shoulders, but it's probably best to do it by hand rather than with the motorized work-sharp, just so that you can more finely control the process as very little material should need to be removed even to reprofile edge.
If you want the flowing convex, do you have a stropping block? I glued a 1/4" piece of mouse-pad to a 1/2" x 2" x 4" scrap of flat wood with notches cut in the ends (I like this size, easy to hold), and I lay polishing paper across it. Quick, portable, and stropping is more forgiving in regards to edge alignment in my experience. I hold the knife steady, blade up, and polish the edge by moving the strop in one direction along either side.
Between uses, giving your knife a quick edge polish (strop) to reduce minute 'stress-riser' deformations in the edge will help keep it performing optimally for longer periods of time. :thumbup:
 
I very much appreciate the advice. Damn shame none of you are close enough for me to trade enchillada plates for sharpening lessons. I jumped on the Busse wagon as JB admitted he was sharpening challenged. After researching JB and realizing he focused more on creating a metal that was forgiving, but still held up I knew INFI was for me. Also, for a knife maker to admit he had a hard time sharpening knives I feel is admirable. to quote Dirty Harry " A man has to know his limitations" I can sell ice to eskimos, but still can't sharpen a blade without screwing it all up. So I know I need help. I think I will destroy some of my old super store blades trying to learn hand sharpening before I tackle this one.

I moved all my blades to a convex edge, again after research here, as everyone stated they were the easiest to maintain in the field. I'll keep the Scrapmax a V edge until I get better at sharpening overall.
 
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