glass cheating.

[Prarie Bowyer]

so,  I'm looknig at the bottom of a beer bottle after having watched the video on doing bottle bottoms.  In the video they trim it to a square then make the triangle.

But why couldn't you use a score and snap method to quarter or even further segment the bottom like segmenting a pie.  cut the bottom in 1/2, then into quarters. I have this tile cutting and snapping tool I've never used but why wouldn't that work?  And you would have less to remove simply to even out the curvature wouldn't you?

[ozy clint]

you need a whole bottle bottom to get a useful point. you would have very small points otherwise.
use your cutter on an old tv screen. you'll get spear point sized pieces

[cowboy]

True, theirs an endless supply of bottle bottoms out there "depending on how much you endulge ". their so easy to work too. You can actually use a fairly course abrader to rough out a triangle and start chipping from there.

[JackCrafty]

You can use a glass cutter.  It works.  The resulting triangles of glass (if you cut the bottom like a pie) will result in some small bird points.  Larger bottle bottms will yield larger triangles, obviously.

[Newbow]

The problem with cutting up bottle bottoms like a pie is the curvature in the bottom.  To obtain the largest point possible from a curved bottom you will have to use the entire center of the piece, thinned to remove the curvature.  If you cut it like a pie, each of the smaller pieces will have a "new" center somewhere in their arc and a much smaller point will be the result.  You could probably nibble out a basic shape without wasting any of the glass you'll need for the maximum sized point, but you'll be doing that anyway as you shape and remove the curve.  Bottle bottoms aren't hard to come by.  Make the biggest point you can, which won't be all that big in the first place, and grab another bottle.

[Prarie Bowyer]

I see what you mean about smaller points.  But if you look at a bottle bottom, ther is MORE removal in thining and flattening if you take a big head out of it than if you take a little head.  I'ts just oriented differently in the glass.  A big one has the  deepest part of the curve in the center of the head.  So to flatten you are taking thickness of the tip and but and the center of the other side.  IF you cut it up pie sized then the curvature is less since the tip is about the center of the blanka and the base is the edge of the bottle.

True it's a smaller point.

But you could still use that process to get the rough out triangle with out needing to "knap" it out of the bottom couldn't you?

[bubby]

get yourself a bottle of yeager or something with a big rectangular bottom, they are pretty flat and you have more area to get a point from, Bub

[Prarie Bowyer]

I either need to raid the local bar or take up alchoholism.  I saw today that SKYY Vodka has the lovley blue ISHI glass  .  $24.00 for so so vodka just won't fly in my house.  I married a Russian.  We bring back a limit of the good stuff when we visit.  Oh and father in law taught me to make a traditional cranberry and everclear drink.

[bubby]

maybe hit up a local bar, might get lucky and get some given to ya, or worst case pay recycle prices

[Prarie Bowyer]

I saw a video on youtube, which I can't find now, of a man knapping mookite from a thin slab he pre-cut on a lapidary saw.  I think this is how the nearly perfect blades are getting made isn't it?

[Prarie Bowyer]

Ishi style speed knapping.

http://www.youtube.com/watch?v=z4Ke0YqqXA0
 

[1ahBprimitive]

i understand being historicly correct but if you '' turn the edge'' with shorter flakes then abraded  you would need less force and would have a ridge system to direct those longer flakes without crushing/stepping problems   

[leapingbare]

Cross section is the key to flawless flake scars.
flake over grind is a easy way to get a flawless cross section but my no means is it the only way.
Just takes practice.

[Prarie Bowyer]

I've watched several videos now (makes me an expert right?) by knapper that are also historians and 1/2 archeologists.  Who of them say that some period pieces seem to show no signs of abrading.  I tend to thin the historical people were not dummies and saught effectiveness and efficiency.  I thought it made sense becasue it's less dropping tools and picking up new tools.  For nomadic people it's one less thing to carry.

bu then if abrading is easier then maybee the give back in speed is made up for in consistency and accuracy ? ?

[Newbow]

I have watched the videos you are referring to and I suggest simply that his views are, to say the least, not universally accepted.  I personally know one lithic expert who does microscopic lab work for an archeology firm, to whom I mentioned these videos, who pronounced it be hooey, based on his own research and lab work.  That doesn't mean that you can't, or even that you shouldn't, do it that way.  If it works, it works and it doesn't make a whit whether anybody ever did it that way in the past or not.  Frankly, I doubt that there is anything we can dream up today that wasn't tried in the past.  If you like the idea of tool simplicity and want to do it Abo at the same time, try using  hammer stones with antler pressure.  The initial shaping and thinning (a good knapper can make exceptionally thin and handsome points just with hammer stone percussion) can be done using the same stone for percussion and abrading and, should you choose to finish with pressure, antler requires little to no abrading, depending on your technique.