pressure flaking patterns?

[Stringman]

Now that rock looks familiar!   

John, dont expect too much from pressure on a preform of that width. You will be doing great to get flakes to run to center. Use an ishi and really focus on "inward " pressure before you let it pop off. Heavy platforms are a must! Also, dont try to get to thin cause you will step easily on a piece like that. Obviously, you need to make all final alignment corrections and fix any convexity issues before the final flake pass.

Now after all that good advise I expect you will go ahead and do what you want and show how you did it anyway... 

Show us a finished point!

[iowabow]

LOl you really are getting to know me well. Scott knows that I push my work to the point of failure 75% of the time. OK I will try to resist the Brass Ring (bug to a light) Syndrome. I have a little cup on the back side of the platform that will present and issue i think. I often start the prperation too late so made the starting point much wider this time.

[iowabow]

Hey scott this time I thinned it to the point I would be OK with without thinning the preform anymore the "Tower Approach".

[iowabow]

Big break through for me today.  I did not do things perfectly but I figured out another piece to the puzzle.  I chickened out on the preform after talking to cowboy on the phone about the preform and I agree with Scott about the convexity issue.  So I start a new preform focusing only on the issue of equal curve divided between both sides.  Now with that said I did not do it great but I did it better so that was step number one.  Next I started a row of flakes from the side that had the most meat.  There is a reason for doing this that you will see later.  After completing a row on the left I over shot on the second to the last flake.  Small over shots will now no longer matter because of new platform preparation.   So as I started the other side things went bad and the second flake stepped and the 5 and 6 did as well so I fixed the 2 flake and left the others because they were in a depression (result of poor convexity) that I knew was going to be an issue before I even started. 
Now is where the fun began.  I always wondered how to create a razor sharp edge without removing the nice pattern from the first flake path.  What I did was to grind with the abrader a platform from the delta on the edge then start removing flakes.....wait it gets better....I also noticed that I can get a straighter line on the edge if I removed a small flake from the valley before applying heavy pressure to the ground delta.  OK so I was thinking that if I removed two small flakes from the valley on each side that might make for a better pattern on the second side.
So my conclusion is that if you don't start with a. Really good preform the pattern will look random and you will run the risk of steps because you are trying to do things the same but on varying surfaces and that will get one in trouble quick. 
Second most important thing I learned was how to keep the pattern on the first side and maybe how to make the pattern on the second. 
Now with this information, and a lot of practice, I should be able to Be able to make this work.   

[iowabow]

[maddog314]

That is sweet I love reading about your "trip to success". it is good stuff...
Micah

[iowabow]

This is unbelievable and amazing jump forward I had to stop and post this point in the middle of making it.   I am not going to finish it so that I can have a record of the plaform preparation and thinkness at start.  I need to keep it as a working tool but I think it is soooooo cool. 

[iowabow]

The areas marked with the X were areas that were low and could persent problems.  The tip was also a problem because it had a lot of chalk in the stone and did not release well.   But wow what nice hour of fun. Stay tuned I am going to try to do a couple more tomorrow.  Tell me what you think.

[iowabow]

Forgot to tell scott that I did use the ishi stick on this one after I moved down 1/3.

[gstoneberg]

Those flake scars look very nice to me.  That looks like excellent progress John.  Maybe after the granddaughters go to bed tonight I'll scoot out to the shop and make some gravel too.  You're inspirational.

George

[Bevan R.]

I think you are going to be in a world of hurt if you drop one of those on her new table.

[iowabow]

OK I can do it twice but on this stone you will see some issues. First the center of the stone has some concrete like material that stop flakes and the basal end has no convexity.   I did this with purpose so that I could find when the flake would stop. 
OK so I now know that the preform has to be just right and the material has to be real good or the process is going to fail.  You will get a nice point but the pattern will be more random and you will start jumping around. 
Now that I can do side A I am puzzled at how the other side is done so I am going to youtube to find an answer.  If anyone wants to head me in the right direction please feel free to do so.

[iowabow]

flintknapper jimmy said that the thickness of the stone will determine how wide the flake will be. looks to be the case seen above

[maddog314]

So, Did you do a ton of "grinding" after you got it to pre form stage?  it looks like you took off all the flake scars, and then did a " Final " set?!?!
Micah

[iowabow]

no grinding before the final pass except on the platform as normal. I just carfefully removed the high spots and small flakes that remained. It will look pretty smooth before you start and that is a good thing.