> Again it's not the borer..... It's the sand
> abrasive the borer forces around the walls and
> under that grinds the grooves (the fig-8 borer
> just touches the walls in two places at the
> beginning of the grinding process and when the
> borer is too small after some grinding another
> longer one is inserted until the desired depth is
So you are saying that the borer can cut a larger diameter hole than its own diameter?
"It touches the walls in two places at the beginning".. Then it somehow enlarges the hole?
After the magical hole enlargement has taken place the operation is then repeated using a larger diameter borer which no doubt "just touches the walls in two places at the beginning"..
Please, Please prototype and test this method, document and publish it.
If it works it could be an alternative to Stocks method.
This process continues down the core
> hole). If you don't like that I noticed you still
> have not got a scale with that drawing.......
> sure you can't stick your hand into it at the top
> with a pebble of sandstone so that a starter
> groove can be ground around the top by hand to
> begin the boring process.
What on earth has that got to do with bore enlargement?
Again calcite (what
> travertine is made all of) is slightly harder than
> your fingernail............ quartz is about 5
> times harder. Let me guess the DeWatt didn't work
> on limestone either?
Prototype the process in chalk or cheese if you like using steel as a boring tool.
Again the relative material hardness is not an issue.
> I provided a couple of images of MM5341 so it's
> pretty clear how much "deviating" there
Yes a few mm deviation.. Is there more than 1cm deviation if so where?