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Posted by Gordon McComb on July 31, 2008, 7:30 pm
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:
>
> 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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> On Jul 30, 4:01 pm, s...@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:
>
>
> This would be my second choice:
>
>
> This would be my third choice:
>