Crushing opposite edge when turning

cnyle
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cnyle
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Joined: May 5th, 2018, 12:16 am

June 12th, 2018, 6:15 pm #1

I seem to have a nasty problem that I cannot quite figure out. But after working one side when I raise my edge I usually end up causing what I’m calling a crushed edge on the side that I just worked. I’m not home to get a picture of what I mean but it causes a nasty series of small steps. Surely there’s a way to avoid this? I’ll add that I usually use either a small hammer stone or my small bopper to do this.
Charles
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boletus
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boletus
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Joined: July 22nd, 2016, 6:15 pm

June 12th, 2018, 7:32 pm #2

Its hard to avoid getting little steps and crushing when you turn the edge. Make sure you abrade the edge first and then raise it. That should help some. I believe ive heard that using a very hard hammerstone to turn the edge can work better at preventing that issue but I still need to put that into practice. I think it has something to do with it being more "shocky". Freezecracked uses a solid copper billet to straighten and turn edges sometimes. Id really like to hear his explanation for that, myself. Hopefully that helps a little. I still have a long way to go with direct percussion too.
-Jason
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cnyle
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cnyle
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June 12th, 2018, 11:28 pm #3

Thanks Jason I will see if abrading helps out any. I already have enough problems without creating more for myself.
Charles
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boletus
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June 13th, 2018, 12:14 am #4

I do a lot of smaller work and I prefer to turn the edge with my pressure flaker. If its bird point size, try that as well. I do it slow and meticulous with just the point of the flaker and work my way down. Im able to keep a really clean edge that way. 
-Jason
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freeze cracked
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freeze cracked
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Joined: October 30th, 2012, 2:24 am

June 13th, 2018, 12:39 pm #5

tilt the working edge down lower when you turn it

i will maybe try to say some stuff on my next video about the issue, but the bottom line is that hinges happen for very specific and understandable reasons and are preventable. 

when you have taken a bunch of flakes, you end up with an edge that is thin and has numerous concavities, and so flakes taken off that edge tend to fail early, tilt downward, and kick up and die, causing hinges. 

there are numerous ways to prevent the hinges from occurring. if you just want to turn the edge a small amount and raise it, by far the fastest method, which many knappers use, is shearing the edge on support. i use copper, steel and bone for shearing, depending on the specific edge characteristics i'm wanting to achieve. i also "percussion shear" with a very coarse abrader. by "percussion shearing" i mean i use the fact that a coarse abrader is flat and has porosity to hit the edge with it rather than putting it on the edge and grinding. 

if you aren't supporting the edge underneath, then the best way to avoid hinging is to tilt the edge downward a fair amount and use a non-"grabby" percussor to start dinking off the edge straight downward, just barely catching the edge. after a pass like that, you can do it again and catch a bit more, and then flip it and do it again to take the "roll" out of the edge that you put there by turning it upward quite a bit. 

understanding edges is a hugely complex thing and i can't keyboard enough in a month to cover it. 

short version - if you want to percuss off the edges to raise them and your concern is having the underside super-clean, tilt the edge down and then hit straight downward with something like a smooth quartzite just barely catching the edge.
i dream of a better world in which chickens can cross roads without having their motives questioned.
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freeze cracked
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freeze cracked
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June 14th, 2018, 2:43 am #6

i just published a video regarding the issue ==> linkipoo
i dream of a better world in which chickens can cross roads without having their motives questioned.
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cnyle
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cnyle
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June 15th, 2018, 1:58 am #7

freeze cracked wrote:i just published a video regarding the issue ==> linkipoo
Excellent information you provided Jerry. I wish I had taken a picture of the mess that I made for myself but I feel very confident that you have provided me and many others a way to avoid one less problem. Thank you!


Charles
Charles
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