A3 plotter on the cheap

[wibblywobbly]

Having run out of space for tanks, build space, and printers, I pulled my old faithful SmartrapPlus apart today and salvaged all of the goodies off it. The parts are worth more than the printer is.

Decided to build an A3 plotter, the idea being that I can load in blueprints that are scaled to 1/16 and simply draw all of the flat hull panels on a sheet of styrene. Then just cut, drill and shape, and I will theoretically have nice accurate panels that I can glue together. No spending hours designing parts to 3D print, at least not the flat parts.

The idea is here:

http://robottini.altervista.org/cartesi ... tter-robot

I still needed to order £40 of parts, but the stepper motors and bolts, and belt drives all came off my old printer. I already have a spare Arduino Uno.

It will take weeks for some of the bits to arrive from China, but I am in no hurry, a plotter this size would cost a fortune to buy, so I am saving myself quite a bit doing it this way.

[43rdRecceReg]

Sounds like a great idea Chris Ludwig seems to use similar technology to produce his kits, unless he takes the blueprints to a commercial plotting firm

[wibblywobbly]

I am always intrigued by those that use styrene that has been laser cut, styrene is known to melt at the edges of a cut, and it takes some very expensive machinery to cut it neatly. I could in theory fit a laser to this machine, but from what I have been reading, it would not produce decent cuts. Acrylic would work though?

I am going to try drawing directly on to the styrene, and then cutting it the old fashioned manual way. I can mark any drill centres and diameters, so they will be easy to do.

[AlwynTurner]

Hi Rob, this is probably a very silly question, but couldn't you replace the pen with an electric screwdriver motor running constantly with a very fine milling bit (1mm?), then you could do the cutting? Presumably the plotter raises and lowers the pen and you could maybe increase the raise/lower height?
Just a thought, I'm really interested in this and might have a bash at doing the same thing.
Alwyn

[wibblywobbly]

Yup, that thought crossed my mind, or even something as simple as a sharp metallic pointer so that it scribed the surface instead of drawing on it. I will have to wait until it is up and running before I will know how rigid the pen holder is. Using it as a router will only work if the resistance on the parts is enough to stop it flexing when anything other than a pen is attached.

[AlwynTurner]

The drawing arm would need to be changed and it doesn't look that accurate anyway. It needs a double arm trapezoidal arrangement to be sturdy and accurate, but that shouldn't be hard to make. With that mod plus a beefed up servo to lift/lower it should handle a small high speed motor and milling bit. The only question would be whether there would be too much play in the y axis arm when milling to give an accurate cut.

A possible mod would be to replicate the 3d printer approach and have the rods span the entire width and just move the pen/mill head along the rods with a belt.

I'm really looking forward to following this build and seeing the final result.
Alwyn

[971wright]

Hi Rob if it will run with a pen it should run wit a scriber point as long as it is only set to scratch the surface, once it has scratched the surface rub over scratch with a finger it should highlight it. don't think it will take a cutter/dremel they tend to heat up the plastic and end up with a messy edge, need to have a good set up to cut plastic with a cutter, change speed and feed also a vacuum to keep the cutter clear, also you would need to add ply to the table or some other sacrificial medium to stop the cutter machining the table.

regards pete

[wibblywobbly]

I am hoping it will run with either, a scribe point would be good, as long as there is enough pressure on it. I now have all of the parts except the 4 rods and a plug in CNC board for the Arduino. It will be an interesting project that's for sure.

[wibblywobbly]

All of the parts that I needed eventually arrived, so I assembled it, which was a challenge but I got there in the end.

The next problem was making it run. There are numerous programs out there that allow you to draw something, but for a plotter the files have to be vectors, not pixels, and it has to be able to save in a specific format. After a lot of faffing about with various ones, and trying to get them to work in Windows or Linux, and sorting out USB ports, plus getting the Arduino program to work...I now have a 90% working plotter.

I am having to use Inkscape on my Linux desktop for drawing as it is faster, but there is no room for the plotter anywhere near it, so I have to copy the file to a Windows laptop and run the plotter from there...and it is an ancient laptop that is dog slow.

Everything works, except the servo to lift the pen arm up and down. The plotter is basically a 2 axis CNC machine, but the Z axis is what powers the servo... it isn't designed to do that. This means I have to find the elusive add on that will send the correct signals to the servo. Once that is done, the whole thing will be ready to go.

[wibblywobbly]

I now seem to have the plotter working like it should, I drew the same shape twice and it traced the same lines with 100% accuracy. The only thing left to do with the plotter is add a servo to raise/lower the pen. The wiring diagram on the web doesn't seem to work, another plotter build refers to different pins, and a different way of supplying power, so I might give that a go.

Once that is done, I need to figure out how to scale drawings in Inkscape, and get the plotter software to draw them to the same dimensions.

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