geek ? on X Y ploters

[shooter]

 just read dougs plexi6V6 thread and replies, did you guys build your own CNC systems?  I was surfing for XY tables and robotic arms a couple days back.  I've been outta it for a few years but wanta build/ buy a feed table with a robotic controlled dremel head.  I got motors, servos, micros.  Mainly engraving/faceplate stuff.  Anyway, thanks for any input

dave

[DummyLoad]

You'll need: a) CAD software, such as Visio, AutoCAD, TurboCAD, etc., b) CNC controller software, c) CAM software, d) Driver/Controller board & Power supply for the servo/stepper motors, e) the machine itself, and of course, f) a PC to run the software that controls the CNC machine...

You start by creating a drawing of the part to machine with CAD software, then save it as a DXF file. Then you use the CAM application software to create a JOB file that contains G-Code. The CNC application software uses the G-Code contained in the JOB file to control the machine.

CNC application software sends the commands to the the stepper/servo drive controller board that should be sized for your servo or stepper motors. Driver/controller will need a high current DC power supply as well, typically 24-48VDC: higher if you're running servos. Usually you can acquire the PS and driver/controller as a package. Be sure to size the steppers/servos to your machine. Cheat, see what similar machines use and plagiarize.

For CNC Software, Mach3 is the most popular CNC control sofware - It uses the PC's parallel printer port or USB to drive the servo/stepper driver control board. There are other packages such as Flashcut, TurboCNC, etc. I pretty sure Doug uses Mach3, as do I.   

The CAM software I use SheetCAM; Doug uses CAMBam: Either works well. The CAM application software usually imports DXF format drawings and converts the shapes you select and want to cut/mill/drill into G code. G code is a language format that you run in the Mach3 or Flashcut environment to control the steppers/servos of the CNC machine. Also in the CAM application setup you define the cutting tools (diameter, length, type; e.g. mill, drill, etc..), the CNC machine physical parameters (X,Y&Z travel, table size, etc..) and then you build JOB files. You select what the job(s) is/are, e.g. milling, drilling, contour cutting, tool feed and plunge rates, tool cut depth, material size, etc.. You can have more than one machining operation in the job file.

The most tedious part of all this is calibrating the CNC software to the physical machine. The ball screw pitch and stepper/servo resolution are factors in the calibration and if you have any gear/belt reduction, then those ratios also need to be factored. If you buy a packaged CNC calibration usually done for you already.

Cutting Tool feed and plunge rates will also need to be mastered: These are based on material type, tool size & type, number of tool cutting faces, rotational speed, depth of cut, machine and tool loading, etc.

some useful links...

http://www.automationtechnologiesinc.com/

http://www.flashcutcnc.com/

http://probotix.com/

http://www.sheetcam.com/

http://www.machsupport.com/

--pete

[shooter]

Thanks DL, it's to late to go surfing, but I will!  I was leaning in sorta an offshoot direction, a feed table, then a flexable shaft dremel controlled by a 3 or 4 axis arm using more of a robotic software, maybe even roll my own, I have a 2 axis rover now that can "wander" the house until he gets to hung-up in the corners  .  the motors can handle about a 5lb payload, pwm, with a 20A controller.  I got about a dozen BASIC II pics,( I still haven't mastered C!!!)  Anyway, I think I got something to keep me in the barn all summer.

[EL34]

Go here and look for the links on my home made CNC machines and 3D printers


http://el34world.com


What you are describing is a small CNC router

[shooter]

I had a bunch of ball-screw X-Y-Z units that came out of old film cameras used in the early days of Cat scanners, '80s.  Like all things, murfies Law was at work, I finally pitched, sold, scraped them before I had a need!  Thanks for the links, as weather breaks and questions arise, like tube amps, I will ask, again this is an amazing mix of brain-trust!!

[MakerDP]

Another fantastic resource is linuxcnc.com

It's free CNC controller software (does what Mach 3 does) and is very robust - people run full-on professional production shops off this software. It will also work on a $25 PC you can get off Craigslist.

[EL34]

You don't need a very beefy machine just to do engraving
And it does not have to be a huge machine


Small steppers motors would be fine
Accurate screws would be a must though

[shooter]

I found servocity.com, lots of small pieces to do a mock-up and get software coded.  Then I can scale up as needed.  I can simply put a pencil at the end.  The small systems I taught in college had a "teach" feature, It put the motors in standby, you moved the arm manually for your APP and the software recorded all the encoder positions per mSec.  Then you ran it and debugged as needed. pretty easy.  But then, I didn't have to write the OPcode !

[MakerDP]

Have you been to this site?

http://www.cnccookbook.com/CCDIYCNC.htm

[shooter]

Here's sorta where I'm heading for the proto-type baby version, (think 12 - 14").  I think i'll have Johnny Cash's song about building a Cadillac on loop while I build