RE: [CAD_CAM_EDM_DRO] VEX CNC

Thanks for the comments. It looks like I am trying to fit a round peg in a
square hole, maybe?? I'm interested in VEX stuff because we have it and we
have a little expertise in programming it. The controller has a Microchip
PICmicroR PIC18F8520 and uses PIC C, and we use EasyC to do the programming.


Am I getting from you that the controller and C might not fit CNC use? I
didn't see a way to interpret shapes, especially without a fair amount of
programming, which isn't the goal. The goal was to find yet another use for
use the VEX platforms we have (or understand why they aren't the best fit) -
I just added the part in parentheses, cuz that looks to be where we are
headed:o))

I get how I could do straight lines in X or Y, but I'm wondering how to do
anything complex, and thus wondering if I am trying to apply the wrong tool
to this job.

Thanks, Chuck

Wreno said:
Hmmm. In'n you want to use C, that ought to work If, however, you
prefer BASIC instead of C, you might want to know about the Picaxe
series of microcontrollers. Only takes a serial cable and 2 resistors
to program them, and they are very flexible and simple (they are
intended for the education market, and are based on PIC
microcontrollers). The IDE (aka the Programming Editor) is free and
allows for in-circuit programming, etc. There is also a native Servo
command They are manufactured by http://www.rev-
<http://www.rev-ed.co.uk/picaxe/> ed.co.uk/picaxe/

There is also a very active and helpful forum on the Rev Ed site.

There are several distributors in the US in the $3 - $12 range depending
on the chip (8 pin to 40). They make a nice 3 servo controller board
for about $12-15 that runs off the 08M that might be just the ticket for
you to play with. Note the Vex servos are wonderful for plugging into
breadboards, but do not plug in to regular R/C type equipment. However,
the serial LCD display cable
http://www.parallax
<http://www.parallax.com/Store/Accessories/CablesConverters/tabid/166/Catego
ryID/40/List/0/Level/a/ProductID/385/Default.aspx?SortField=ProductName%2cPr
oductName>
.com/Store/Accessories/CablesConverters/tabid/166/CategoryID/40/List/0/Level
/a/ProductID/385/Default.aspx?SortField=ProductName%2cProductName
will adapt it to standard hobby RC equipment.

Drawing circles might be "interesting.", though straight X/Y lines would
be pretty straightforward. Do not expect incredibly high accuracy with
the servos, though.

Cheers,

Wreno

ebiz_59 wrote:

>
> My highschool science club is the proud owner of a couple VEX kits -
> erector sets with brains. We are thinking of making a CNC project
> with this VEX - more as a learning exercise than functional. We would
> probably just use a Sharpie pen on paper, or something like that. The
> motors are controlled by a servo PWM signal as we understand it, and
> we can create autonomous functions. However, that programming is done
> in C, and I can see where we could make a square, or even a slanted
> line, maybe, but I'm puzzled as to how to make, say a circle or
> something more complex than a straight line. Are we going to have
> more problems than it is worth, and learn mostly that we need to
> finish our stepper controller, and use a CAD/CAM program to do this,
> or mgiht this be an interesting project, if the mentor just knew what
> he was doing?? Thanks, Chuck
>
>
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7:04 PM

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