Homebrew CNC Gantry Painter

[vacpress]

publitime - checkout the "free rip" program on the pixelation site. it may provide a key also..

and searching on the perl GD libraries is also very usefull, and someone recomended reading something called the "comp.graphics faq" so im gonna hunt that down for bedtime reading.

gotta do this homework... whats HyperXpress?

[jeffterm]

I FINALLY found this thread again! hope I can add to the game.

I recently wrote a VB program converting a BMP into gcode for 3d engraving on our bridgeports here at work. Your coordinate system does not need to be complicated since your going to run through your entire image sequentially. i.e do complete first row - return home - goto next row - do complete row - return home. Yes you can add complexity if you want to print bi-directionally - but lets walk first - run later;-)

Keeping this Raster frame of mind eliminates the x,y issues, but keeps you color mixing at the print head. Since all graphic images are broken down into pixel grids all you need is to take the color values at each location and time the 'spray' based upon its value. The value is relative to the sprayer and will need to be fine tuned during assembly.

My 3d engraver used the color density to determine depth on the z. Your case would have to send all 3 parameters separately for each color. Very do-able in my mind.

[publitime]

jeff

can you give littel more info about how you see the controller for the printer?
What electrical components are needed to run.
With what program will you run the whole thing

[vacpress]

jeffterm - thats what i am comming to realize. i am also building a prototype. i was going to use acrylic, but have been forced to compromise the design because acrylic costs to much. so sad, but the 4 pieces i need will aparently cost me $40. i am far to poor to spend $40 on acrylic. The guy who I normally see wasnt at the plastic shop today. SOO, i gotta either find a cheaper source for some 1/2" acrylic or, change to MDF or something.

the software you describe sounds interesting. i have decided basically to try and get a 48" wide gantry up by the weekend and on wheels. i have a tiny computer im about to put an array of DOS CNC software on to test the thing. I just need to order 2 more xylotex drivers, but have some 1-pulse/step unipolars i made that will allow me to get the thing moving as long as i use unipolar motors. im gonna try and make it have auniversal nema mounting scheme tho..

jeff- for the latest software scoop goto:

www.luberth.com and checkout cstep - thats gonna be for the vector mode. AND
www.pixation.com goto the downloads site and checkout the "Free RIP" program. that may be for the image prep. Or ghostscript. Then it needs to be decoded and printed: custom perl script, maybe even in an IC, with a windows style driver that sends the program and parameters to the board.

You may have an easier solution - a simple G code scheme with a seperate command for each color, and a good post processor application that generates the code?

there is a GCODE in a chip opensource Atmel project. I bet that could be customized very easily to work specifically with the program you created. The program you made needs a few thing smost likely to be just right : output resolution, output size.

Tell me more!

SO. Axrylic:

$195 for a 4x8' sheet
roughly 7$ sq/ft

its wierd, last time I went there, the guy who i delt with was really cool, gave me lots of stuff for $10. this guy wanted me to pay $45 for a 1/3 sheet. sooo. i said no thanks.

[publitime]

vac

i can mail you very good cnc software that is running in DOS.
It will translate a hpgl to G Code.
It's very easy to use.
The software is from one of my friends who lives in germany so its German language.
But my wife did translated it to englisch.
It is 2,5D cnc software.

[publitime]

vac
I'm thinking to see if it is possible to rebuild a injector to a printhead.
I means the injectors you find in a gasoline engine to spray the gasoline in the engine.

[vacpress]

thats an interesting idea. how many nozzles are in an injector?

[jeffterm]

OK, I'll see if I can keep up with you guys on this. If work does not get in the way.

How prototypical do you want to proceed with this just to get a proof of concept? We could make some quick decisions now that would 'get the thing to print' but in the long term might not be such a great concept.

On the other hand, I'm really sure we could spit something out that gets the thing to move & spit ink(paint) at a wall just to get the incentive to continue working on it.

Whose call? vac-this is your baby.

I see the logic as this: The image needs to be processed. Top down, and left to right. each pixel will be processed for color values and sequentially sent to the gantry. The gantry will take this information, break it down to timed pulses for solenoids controlling the air/paint. (deeper color - more/longer pulses) for each color. upon completing the cycle the gantry will step one pixel and start the next color pulse. When the end of the row is reached the whole gantry drops one pixel and starts again. Preferably in the opposite direction (but this adds more to the code than I ever thought it should - but I'm rusty)

Over simplified, I know but its been working for HP / Canon / Lexmark for years why change it? What we should not do is look into vector driving at this time, I dont think it is what you guys want. I might be wrong but, for multi-color prints aka pixelation.com the vector prints will give a more grafitti look & becomes more difficult to comile the image for process. -- somebody tell me if I'm wrong here?

I am really scouring the luberth site now, because I feel there are some great things here. If we can offload the stepper control onto a PIC, it can be programmed for simple commands: x-step-right, x-step-left, y-step-down, and all the required pulsing can be done here. This would incredably simplify the PC program and just require breaking down the graphic image. This does make the entire thing more proprietary- instead of g-code we'll be sending 'vac'-code.

[jeffterm]

publitime
- just a note on the automotive fuel injector: I played with some a long time ago out of a Datsun 'Z' car ;-) I never got the signal pulsing to work and was told that by just adding power to the injector, thinking it would 'just stay on', basically ruined the injector. Also, they operate at a relatively high pressure. 50-60psi if I remember correctly.

- for a chuckle - I was trying to build a snow machine with mine ;-)

[publitime]

jeffterm

A injector is working at a very high pressure that's right.
But you can rebuild the injector so that he will open at a much lower pressure.
The only thing that could be a problem is that the nozzel will be clogged because he is very very small.
Maybe paint won't come out of the nozzel because he is so smal.
We have to become a dot and not a splach of paint so the nozzel must be smal.
One of the plus point with a system like a injector is that you don't need a airflow true the nozzel.
The only compressed air you need with a injecto is to put pressure on the paint tank.
Maybe there are people here arround who will have a better suggestion.
So let us know all suggestions you have.

[balsaman]

So, when does the building start?

Eric

[vacpress]

CNC Gantry Painter Build Pics - Night 2