Re: Digest Number 249
Posted by
Patrick Huss
on 1999-11-23 16:20:29 UTC
Andrew Werby wrote:
I have used this method many times while machining sculpture. The only
difference was that I would use 4 paths indexed at 90 degrees.
[The 3 paths/120 degree strategy was just to test things out. In practice
I imagine that the strategy used would depend on the individual sculpture-
if it required six or seven passes spaced irregularly to get into the
details, then that should be possible. I'd love to see some pictures of the
sculptures you've done this way- do you have a website or anything? What
kind of a setup are you using for this, and what software?]
Well I was machining this way while I was an employee of the Johnson
Atelier, machining stone sculpture. One main difference was that we were
using a laser scanner to scan the model into the cam system. The software
was CARSO by Scan Technologies of Denmark, not exactly in the home machinist
budget, but we can dream.... We also used Solids manufacturing from VERO.
The setup involved setting an origin at a known location on the machine, and
using the same origin for each tool path. Since every toolpath has the same
origin, you just index the work piece, move the tool to the common origin
and push start. The most important part is setting the origin in your cam
program to match the one on your machine exactly.
Now days, I'm on my own and I use a table-top mill from EmcoMaier. This mill
is capable of operating as an horizontal mill, so when I can buy a nice
indexer I'll be working as you are. Until then I use a multi-stepped process
that involves machining a negative of one side of a model, machining a
positive (the same side), and using the negative as a jig to hold the milled
side of the model while the final (other) half is milled.
Does that make sense? I call it "creative fixturing" : )
I have a few pictures of stone sculptures which, time permitting, I will get
on my web page this week. My page has suffered from a severe lack of my
attention and so contains dead links and is missing pages, but anyone who
would like can check it out at http://patrick.huss.com warts and all!
Patrick Huss
I cant begin
to tell you how many times I heard "we are artists - we don't need to work
to those tolerances" well the fact is that we aren't just artists any more -
we're machinists too.
[Believe me, I'm realizing this (kicking and screaming all the way). I
suppose it was vain of me to expect to eyeball the center of a cutter, but
I also didn't figure on my error being subject to a multiplier effect-
although I should have.]
If your finished piece is going to be covered in clay
or whatever, then the tolerances may not be so important, otherwise ...
[No clay- I like the surfaces I get from the milling cutters- at least when
things are going well...]
Andrew, have you ever visited Bill Kreysler up in Petaluma? If not, I would
recomend it!
[I have, and I was in awe of his ingenuity. (I have his site on my links
page). For those who haven't made the pilgrimage, Bill Kreysler built his
own CNC machines from scratch, and they are quite large. He uses a
different strategy, though- cutting one linear pass (that varies in Z) down
the x direction, then indexing the A axis over a cutter radius or so, then
making another linear pass, etc. Mostly he cuts foam and covers it with a
thin layer of clay for the final surface (which is molded and cast in
fiberglass). While this is a simpler method for carving fully-round parts,
it isn't as versatile as the superimposed-contours method I've been working
on and you've been using- no undercuts are possible. Thanks for confirming
that this can work- I was afraid there was some fundamental problem I
hadn't thought of.]
Andrew Werby
http://www.computersculpture.com
Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com
>[Does anybody else machine parts this way (superimposing severalway?]
>contoured toolpaths), or do people using more sophisticated programs
>approach the problem of milling fully-round irregular parts some other
I have used this method many times while machining sculpture. The only
difference was that I would use 4 paths indexed at 90 degrees.
[The 3 paths/120 degree strategy was just to test things out. In practice
I imagine that the strategy used would depend on the individual sculpture-
if it required six or seven passes spaced irregularly to get into the
details, then that should be possible. I'd love to see some pictures of the
sculptures you've done this way- do you have a website or anything? What
kind of a setup are you using for this, and what software?]
Well I was machining this way while I was an employee of the Johnson
Atelier, machining stone sculpture. One main difference was that we were
using a laser scanner to scan the model into the cam system. The software
was CARSO by Scan Technologies of Denmark, not exactly in the home machinist
budget, but we can dream.... We also used Solids manufacturing from VERO.
The setup involved setting an origin at a known location on the machine, and
using the same origin for each tool path. Since every toolpath has the same
origin, you just index the work piece, move the tool to the common origin
and push start. The most important part is setting the origin in your cam
program to match the one on your machine exactly.
Now days, I'm on my own and I use a table-top mill from EmcoMaier. This mill
is capable of operating as an horizontal mill, so when I can buy a nice
indexer I'll be working as you are. Until then I use a multi-stepped process
that involves machining a negative of one side of a model, machining a
positive (the same side), and using the negative as a jig to hold the milled
side of the model while the final (other) half is milled.
Does that make sense? I call it "creative fixturing" : )
I have a few pictures of stone sculptures which, time permitting, I will get
on my web page this week. My page has suffered from a severe lack of my
attention and so contains dead links and is missing pages, but anyone who
would like can check it out at http://patrick.huss.com warts and all!
Patrick Huss
I cant begin
to tell you how many times I heard "we are artists - we don't need to work
to those tolerances" well the fact is that we aren't just artists any more -
we're machinists too.
[Believe me, I'm realizing this (kicking and screaming all the way). I
suppose it was vain of me to expect to eyeball the center of a cutter, but
I also didn't figure on my error being subject to a multiplier effect-
although I should have.]
If your finished piece is going to be covered in clay
or whatever, then the tolerances may not be so important, otherwise ...
[No clay- I like the surfaces I get from the milling cutters- at least when
things are going well...]
Andrew, have you ever visited Bill Kreysler up in Petaluma? If not, I would
recomend it!
[I have, and I was in awe of his ingenuity. (I have his site on my links
page). For those who haven't made the pilgrimage, Bill Kreysler built his
own CNC machines from scratch, and they are quite large. He uses a
different strategy, though- cutting one linear pass (that varies in Z) down
the x direction, then indexing the A axis over a cutter radius or so, then
making another linear pass, etc. Mostly he cuts foam and covers it with a
thin layer of clay for the final surface (which is molded and cast in
fiberglass). While this is a simpler method for carving fully-round parts,
it isn't as versatile as the superimposed-contours method I've been working
on and you've been using- no undercuts are possible. Thanks for confirming
that this can work- I was afraid there was some fundamental problem I
hadn't thought of.]
Andrew Werby
http://www.computersculpture.com
Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com