another question.

[triggerfinger]

So i went to my moms and dug up some stuff that may work, some definitely will.  I made my first biface and was so stoked i decided not to risk breaking it.  So now im all excited and wanna keep going. heres the question.

I fou d a couple of thick bottle bottoms in an old trash pile.  I got the bottoms seperated from the bottle but have 90 degree edges now and no idea how to get rid of them.  Percussion flaking has just ledt me with a smaller piece and similar bottom angles.  I tried to find some youtube advice but couldnt find anything.   Help please.

[iowabow]

Hard to explain but I will try.  I think there are two ways to approach this type of problem. First you can pressure flake by taking flakes from the support side of the piece.  This is done by placing the pressure flaker below the center and appling pressure downward.  This should remove the first flake and you simply continue by following the ridge that you create.  Then you flip the work and repeat the process on the other side.  By the time you finish the second pass on each side the sides should start to meet. 
Second way is to scissor the edge by alternating sides to remove flakes thereby bring the two edges together.  For examples search youtube for how knapper work slabs.  Slabs are sawed pieces of flint.  These slabs have the same problems to solve as your glass.  There maybe other ways to tackle this problem but this is all I know.

[cowboy]

I was going to say the same thing more or less. Stitch the edges to give yourself some platforms to work with. You can do this with either percussion or pressure. Take a flake off anywhere then proceed to alternatly knock flakes off both direction's. One flake this side, flip your peice, take another flake all the way around back and forth. Then work it as usual. Yes, youtubeing slabs would probably make more sense..

[triggerfinger]

I know you guys are trying to help, but im completely lost.   I can get the deltas going around the edge, but cannot get it to thin any.  When I try I either break the piece or square it back up on the second pass.  I really need a few minutes of instruction.  Danged ol paleomanjim doesnt wanna fly out and give me some time.

BTW  We absolutely slaughtered the prairie dogs, to those who have been paying attention.  Hit my longest shot  860 yd with a .308 it was  at least 1/2 luck

[iowabow]

Funny I posted the same post about 6 months ago.  I know exactly why you are having trouble.  Any chance you could post some pictures of the piece you are working on.

[iowabow]

Here is a link to that post I made 6 months ago.  The reason I am posting it is so you can see that we start from the same point.  If you keep working at it it will come.  http://www.primitivearcher.com/smf/index.php/topic,22851.msg309227.html#msg309227

[triggerfinger]

Funny I posted the same post about 6 months ago.  I know exactly why you are having trouble.  Any chance you could post some pictures of the piece you are working on.

I am pretty well having trouble with every piece at this point.  But my biggest prob is just 90 degree edges.  I wish I could post a pic, but use an Ipad and it is pretty well impossible to get pics on it.

[JackCrafty]

Watch this video:

http://www.youtube.com/watch?v=QGT1sU0_NL0&playnext=1&list=PL90A589ED8A1C1F05

[triggerfinger]

Watch this video:

http://www.youtube.com/watch?v=QGT1sU0_NL0&playnext=1&list=PL90A589ED8A1C1F05

Awesome, I think this set me straight.  Actually it led me to the right video by paleomanjim that set me straight.  Look up paleomanjims part 2 of knapping slabs.  He had a perfect example of what I was messing up.  Also had some great detail shots like he usually does. 

[iowabow]

Run now and don't look back or you will be hooked for ever.

[triggerfinger]

Run now and don't look back or you will be hooked for ever.

Wish you wouldve given me that advice last week.....it might have worked. 


Also what purpose does abrading serve.  I see people do it on the vids but they dont say why

[YosemiteBen]

Abrading removes any micro flakes that were left over from your last round of pressure flaking. It builds stronger platforms for driving flakes at least halfway across your piece and in some case all of the way so be careful.  Some folks I know have used spalling to the same effect.  It is an easier way to remove large amounts of material from an edge and change the location of your platforms before you begin pressure flaking.  In spalling take an antler tine and starting at the "tip"apply a cutting motion (much like you would slice cheese) to the edge of the piece. If you want to experiment start with a piece of junk to see if you might like trying it that way. As always practice, patience, time and discussion with other knappers will get you where you want to go. Good Luck.

[triggerfinger]

He called me a knapper....i could cry a little