Re: [CAD_CAM_EDM_DRO] Re: Flashcut vs desknc for windows & Deskam

aspaguy wrote:

>(snip) I did resend the e-mail to flashcut and got a quick response.

unfortunately, as a newby the benefits they described

> were over my head and I'm not sure that weather deskwin nc has the
> same benefits or not.

Glad you were responded to. Well, it is a challenge I am sure for Both
parties in this case to understand some things. For the Vendor, he almost has
to think way back to his understanding when he started, and the purchaser ?
Well, he has to do quite a bit of homework to know what the Vendor means.

> like what is Continuous contouring?

Well, just a short time back this discussion came up in this group. Many have
some real sophisticated ways to explain it, but, thats because CC is a very
sophisticated feature to have in a program.

In short, for the not so smart which includes myself, You NEED IT ! It is the
softwares ability to "look ahead" at the code and decide if it can run thru
mixed geometry (toolpaths) without slowing down.... Or if it does have to
slow down, how much it slows down.

Picture for a moment some lines drawn on a piece of paper, in the shape of a
box with 4 sides. To cut this at a pretty good "clip", your router would have
to simply follow the lines one at a time, slowing down as it approached each
corner so it could change direction to do the next line. This would be called
"Ramping". the machine starts slow based on a setting you make in a setup
file somewhere, then accelerate to the speed setting your code tells it to
go, then deccelerate to a "Safe speed so the machine does not lose position
when it turns the corner. If one were to go to fast thru this corner, you
should be able to envision that instead of a nice crisp and sharp corner, it
may be slightly rounded and out of shape. So much for a simple corner with
straight lines. keep in mind that the machine is told by the "setup" you
select to run that toolpath at feedrate whenever it can, slowing down when
necessary.

Now, Long sweeps in a drawing are often a "mixture" of "arc commands"
(G02-G03) that have been "fitted" to the shape >if possible< and also very
short "straight line segments" (G01) when not possible. So, lets assume you
make many, many very short lines in the shape of a circle. Some software
output will always do this. You should be able to recognize that the
"direction change of each line" is very slight when in the form of a circle,
not at all like a square corner found on a square box.
Now, if you DO NOT have "Continuous Contouring", your machine will likely
have very minute pauses, as it reads from one line of code to the next (where
the change of direction occurs), and it will also "attempt" to reach your
maximum feedrate "within the length of each line" it travels. The "Ramp"
settings we discussed above might not allow the machine to EVER reach the
feedrate, because the line is too short (based on the setup you have
dictated). This causes the machine to "accelerate" as much as possible

>UNTIL< it needs to Deccelerate at the end of the line to make the direction

change. The result is a very jerky motion which can sometimes start and stop
your machine way more than necessary.

Some controllers will really drive you nuts doing this while others will have
an almost un-noticable pause. usually they all can leave tooling marks where
these "Jerks" occour. Controllers without Continuous Contouring often work
best if they "never" have a series of real short connected lines. Simple
"Line and Arc" commands, with some controllers may not show this "jerkiness"
on a machine that runs under 20 or 30 IPM. It is a whole different story when
you need to run above those speeds. If you build a router, You need higher
speeds to keep from burning up yur router bits when in hardwood, and keep
from melting when cutting plastics. I never owned a Sherline sized machine.
But, I could conclude that simple 2-1/2d work would not require contouring
because of the maximum speed it can run at.

Now Contouring in its fullest sense. When you run your square box toolpath,
the controller really runs the same way. It will accelerate, attempt to reach
your feedrate, then deccelerate so it can make the corner with undue stress
on the machine.

Enter in the Circle made up of very short line segments. Now your machine has
an option. Based on settings you put in as they will be different for each
and every machine, Your machine now "looks" at the lines of code ahead of
time and decides whether the "Corners" or "direction changes" that will be
made to follow the path will "stress" the machine or whether the machine
could run thru them all at the feedrate. The FlashCut control which I am very
familiar with, will take all of these short line segments and execute them as
a single arc or circle, running the entire path at feedrate. NO jerkiness, or
stop starting. This ability becomes much more important when you run "mixed
geometry" or Splines. Like I mentioned before, sometimes the "Code" created
to represent the path will use a mixture of short line segments and also arc
commands.

The function of Constant Contouring blends all of these together.

The best under $1000 control for contouring I have used is the Indexer LPT.
With a windows "interface" it was probably one of the first to offer
contouring for that kind of money. Unfortunately, they only had the ability
to read hpgl or native code. Recently, they have released a G-Code interface.
It will be interesting to hear reports of how it works out.

FlashCut is the runner up to that, from what I have used as far as motion
itself. (Windows based) I have used a few DOS controls with Contouring and
they did not give the results I get with Flashcut. If you do use a DOS
version, be sure you have access to the settings related to contouring. It is
beneficial to be able to change them to fit the application. In the case of
FlashCut you can even change them and save them to fit a job thru different
"setup" files.

The other windows based controls spoken of here are best addressed by their
users. Great advances have been made, that is for sure. Some have come and
gone though too ! Black Box ?? Well Indexer LPT does not use one, and may
just have the best contouring available for that kind of money. I do not see
anyone else outbragging the depth of Indexers "look ahead" features. Its only
disadvantage in the past was a little extra wiring and it hpgl 2.5d
limitations. So, the Black Box thing may not be necessary....... I would like
to know why everyone has tried to do the "windows" thing and struggled along
getting it right. It had been an open door for somone just to overlay an
interface to Indexer, windows OR Dos.Why no-one ever made a complete g-code
windows interface for Indexer before I'll NEVER understand. Then again
nothing stops anyone now !

> And what about tool radius
> compensation. I would assume this has to do with cutting a square
> hole with a round bit and getting corners that are radiused the same
> as the bit radius, but i don't see how software can fix that.

NO. (not square hole- round bit).. I do not use radius compensation now. I
have used it with other machines but do not really use it or miss it now.
Flashcut currently does not have it but will soon. I just measure the tool I
am going to use when I create the toolpaths per tool. This way I do not need
to even bother with a big software tool library. If you are a machine shop it
may be important. hobbiest ? probably not. (here come the arguments!)

> Speaking of cam, Chris, the funtion of
> Creating G code from Dxf is handled in Deskam, then Desknc uses the
> g to run the drivers.

yep... got that part figured out :-)


Chris L