Getting a bottle bottom out whole?

[TreyNC]

So I made my first points today! Yes they are ugly and non functional. I used glass bottle bottoms. My question is how do I remove the upturned rounded edge of glass? Every time I try to break this off to have only the convex bottom, I break the bottom into two pieces.

pics to come.

[Hillbilly]

Usually if you use the shake-the-nails method, there isn't much edge. You can usually trim it off carefully with a small hammerstone.

[xin]

You  are on the cusp of learning a valuable lesson that will carry over into the knapping of chert, especially long pieces of chert.  Be very careful when hitting the turned up edge. care must be used to hit it hard enough to get off the piece you want but not hard enough to break the piece in half.  You will remember this when you have a good Clovis pt going and you hit the end too hard  and it breaks in half.   

[james parker]

the old ronco bottle cutter,or score a line the heat over a candle while spinning the bottle slowly

[leapingbare]

Hey Robustus, i enjoyed your new web site.
Anyone who has not yet checked it out.. its really cool.

[uwe]

Tie a petrolsoaked cord around the bottles bottom, light it and wait till its burned off, then put it into water and the bottom will fall off. There`s another effect, you`ll have a windlight now. Put a candle into the bottleneck inside.

[mullet]

 Diamond saw or Tile cutter works wonders ,too.

[TreyNC]

Thanks for the info guys, it's going better. Now I have to try to control the flakes to convex the concave side, this is not so easy for me.

[ZanderPommo]

saw a trick on tv
fill it w/ water almost to the top, then whack the hole w/ your palm, the pressure will pop out the bottom
(don't hurt yourself)

Zander

[DanaM]

Check out this video its the best one I've seen on knapping bottle bottoms


http://www.youtube.com/watch?v=xh7pc2Q6XFI

[madcrow]

The prettiest too.

[DanaM]

The prettiest too.