Less than a newbie

I want to start tinkering with robotics, more specifically, I'd like to make a portable X-Y plotter to take on location to print on things
like sheets of drywall or plywood. For now, I'd like the device to only be about 2 ft. by 3 ft. and be able to place it directly onto the surface to be printed on. I'm guessing that some of the things I'll need is two stepper motors (unless another type of motor would be better), a controller board (like Arduino or better?), a print head, and the railing and arm for the print head to ride on. Not to mention some sort of programming to make it work. Does anybody know of any website where people did similar projects and documented it? Any suggestions on books or websites where I can start with the fundamentals? Any body interested in helping a complete rookie with this?
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I recall seeing something like this about 20 years ago. It was intended to be a low cost substitute for a stand-up pen plotter. However, I don't think it ever succeded.
A good start might be an old pen plotter. Since ink-jet plotters now dominate, many places are getting rid of the old pen plotters.
Here is another source of info. http://www.cnczone.com They have a few forums related to home made CNC machines, and also one for plotters.
Joe Dunfee
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On Tue, 29 Jul 2008, bolts wrote:

I seem to recall someone in a recent issue of Servo, Nuts and Volts, or Make or some such did a home brewed wall plotter which could be arbitrarily large, and worked in such a fashion ... sorry, I don't have the reference to hand, but it was definitely in the last year or so ...
HTH, Rob. ---- Posted via Pronews.com - Premium Corporate Usenet News Provider ---- http://www.pronews.com offers corporate packages that have access to 100,000+ newsgroups
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It appears that the article was in Circuit Cellar:
    March 2008 Issue 212:     Vertical Plotter System, by Miguel Sanchez, p. 30
You will likely have to purchase the .PDF file from Circuit Cellar if you can't find the issue ... hmmm ... Looks similar to what you described.
HTH, Cheers, Rob Sciuk
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On Jul 30, 4:01 pm, snipped-for-privacy@controlq.com wrote: hmmm ... Looks similar to what you described.
I don't think I explained it well enough. I want this for printing on large horizontal surfaces, and it will need to be rock solid. Things hanging from cables and pulleys are out of the question. It will not actually be a "plotter" but more of a "printer" since it will be using a 256 nozzle industrial inkjet head.
THIS is an "On Steroids" version of what I'd like:
http://www.youtube.com/watch?v=nHnNpzflfaE&NR=1

This would be my second choice:
http://www.youtube.com/watch?v=B-CfNfIWGWw&feature=related

This would be my third choice:
http://www.youtube.com/watch?v
hnzPZPYB4&feature=related
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You need to buy something ready-made if you are less than a newbie and have the stringent requirements you specify. Let's be realistic. You are not going to be able to build one of these yourself.
I don't know who sells these, but they are used by billboard and sign painters. They are "rock solid" and large, and support the type of print mechanism you speak of. I imagine the cost is going to be in the tens of thousands for the mechanism alone. Software is extra, and may need to be custom-designed to support your printhead.
I'd go around to some of the larger sign printers in your area and see what kind of machine they use. Then look up the company in Thomas Register or Google for a phone number and address.
bolts wrote:

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Fair enough. I actually don't need for it to billboard size, but at least 2ft x 3ft. I'm actually "brainstorming" this for something I'd like to introduce in my place of employment. We manufacture light construction equipment, so I have access to an engineering department and a manufacturing facility. I'd like to just have some sort of mock up as a "proof of concept". It won't need all of the bells and whistles I'd like to incorporate. I was hoping maybe somebody in here could give me some help/advice on throwing together something even as clunky as this: http://www.pitstock.com/robonz/news/plotter.html
I just need to test the whole inkjet thing to see if it does what we need before I try to suggest we spend a metric pantload on R&D.
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A workable area of 2' x 3' means the gantry has to be about 3' x 4'. You need the extra to accommodate the width of the printhead (or cutting tool or whatever is being moved.) The larger these get, the higher the price. If you could scale to say a 25" by 25" area, the cost could be driven down to a few grand. Outfits like Arrick Robotics sell workcell systems of this size, for example.
You need the following components:
1. The X/Y bed itself. The larger the cell area, the higher (often exponential) in cost. A 2' x 2' X/Y workcell that will move a load of any mass while holding accuracy costs $1,000-3,000 depending on type. As you go bigger you need to use larger and heavier materials to maintain accuracy. You do not want to buy something small only to need it larger later on. You don't really "stretch" these out. Whatever you buy should be the size you need.
2. Motors and motor drivers. You have two choices: stepper and servo. You'll probably want to use stepper because you need a consistent scanning speed and want to minimize costs. You need driver electronics. A decent package here is $700-1,000.
3. Software. CAM software of any decent quality isn't cheap. Many of the good packages start at about $500, and go up (quickly) from there. You want one that will handle raster (not vector) scanning. Many of them have this feature, but you need to check. You somehow have to coordinate the unique printhead functionality you require with the software. Most software is set for actuating a Z-axis motor (for router cutting operations), a laser beam, a water jet, an acid jet (glass etching), or a single-channel or multple channel print head. The multi-channel printheads are used to print in color, typically 4 or 5 channels. If your printhead has such features as variable ink pressures (as opposed to simple on/off) or whatever your search for good software is going to be much tougher.
Looking at the lightweight construction of the plotter you mention I don't see how it will hold the accuracy you need. But, if you don't need high accuracy, and your printhead weighs just a few ounces, then I don't see why you couldn't build something like this, at least for proof-of-concept. But I don't think you need a proof-of-concept. We know the idea works. It's not the design of X/Y tables that's the problem, as these things are mechanically very simple. It's making them solid enough to handle the size and weight for the job.
bolts wrote:

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The Turtle of Terrapin Inc / Dan Hillis did that in 1978 ( " Turtle Plotter " ).
Best known commercial plotter of that sort was probably the Penman http://www.embeddedforth.de/temp/turtle1.pdf Google will find many pages for " penman plotter "
Later there were industrial versions. Thats a german one: http://www.embeddedforth.de/temp/turtle2.pdf But these did not gain much acceptance.
MfG JRD
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