Airbrush on ShopBot??

[andrewm]

Has anyone ever rigged and airbrush system up to a Shopbot for painting? If so, how successfull was it and what type of setup did you use?

Andrew M

[gbatten]

Good question Andrew. I have thought about the same thing but never posted a question about it. Maybe someone will reply with advise on an airbrush attachment.

...Gene

[oddcoach@aol.com]

NORDSON MAKES ALL KINDS OF AUTOMATIC GLUE AND LIQUID APPLICATION SYSTEMS. THEY AREN'T CHEAP BUT THEY ARE VERY GOOD SYSTEMS. I HAVEN'T PUT ANY ON THE SHOPBOT, BUT HAVE USED THEM INOTHER INDUSTRIAL APPLICATIONS.IT COULD BE ASTUATED WITH A MICROSWITCH ON THE Z AXIS. AS THE AXIS MOVES DOWN THE SPRAY IS ON UP FOR OFF.THERE SITE IS WWW.NORDSON.COM (http://WWW.NORDSON.COM)

[M. Holm (Unregistered Guest)]

My reaction to this suggestion would be that extraneous glue/liquid residue would get on the exposed S.B. mechanism itself and affect it adversely

[andrewm]

I am not looking to do large scale painting of whole parts, but the highlighting of details with a focused fine airbrush. The kind of detail work that would be done by an airbrush artist not a house painter.

I remember seeing a robot doing airbrush t-shirts at Disney's Downtown Disney about a year ago. Theirs was very theatrical in its presentation, but its movements were very similiar to those which can be achieved by a ShopBot. There was very little if any overspray. It was a very clean operation being performed right in a store.

In my case I am looking for a way to reproduce fine detailed work that I need to be replicated over numerous peices without depending on an artist each time.

[Brady Watson]

Andrew,
It is *possible* to mount and use an airbrush on the Bot. However, you have to figure out if it is going to be worth it to you or not. You would have to stick to a single action airbrush with a basic on/off configuration. Trying to manipulate a dual action brush would entail a lot more ingenuity and a LOT of programming time for each design.

Theoretically if you are just going to do fine lines you could get away with using a relay and some type of servo to press the brush/gun trigger. You could use the output switch to control the off and on in software. Make your "profile toolpath" and then add a line to the code after each section to turn on or off.

You will of course be spending a lot of time experimenting. Find a single action brush with a side cup that can be rotated parallel with the body (so that it will hold paint). Then make a mount that will attach the brush to the Z. Add a pressure regulator and gauge to your gantry. I would advise using magnets to hold this onto the gantry. Old harddrive magnets will take your finger off...they are so strong. Do this as close to the brush as you can because pressure at the compressor is higher than at the location of the brush...there is a substantial drop in pressure at the head because of the rubber lines.

Search the archives for how to hook up a relay and use the output switches.

Get to it!
Let us know how you make out.

-Brady

PS- You may also be able to use an electro-pnuematic switch if this doesn't adversely affect the finish (like sputtering etc) You could simply send the swith a signal from the output switch and it will open the valve and activate the brush...turn it off and pressure is off.

Also, it dawned on me that you will need a 'purge area' to get the paint flowing properly and dialed in.

[billp]

At the Atlantic City Sign Show 2 years ago they HAD a vertical CNC "auto painter" which was doing exactly what you are desctibing. During the course of the show it painted a mural on the entire side of a van and it was composed of MANY colors.. I have NO idea of who manufactured the machinery but you might try the USSC sign council web page or member listing to get the info..

[Lee Cheney (Unregistered Guest)]

There is a small company here in Utah that has been developing and marketing a couple of machines that "print with paint". I have been following them for 4 or 5 years. Their technology is unique but more expensive than Shopbot. Their web address is:
www.pixation.com/ (http://www.pixation.com/)
I hope you find this helpful.
Lee

[K Simmerer (Unregistered Guest)]

A few years ago someone was selling an airbrush setup that used a manifold that standard airbrush bottles screwed into. It used like 10 colors and a bottle of water. It fed the paint under light pressure down a cable-like array of very fine plastic tubes to a selector valve, and then a single line to a standard siphon feed, internal mix, single action airbrush pickup. There were a few common airbrushes that it worked with (Pasche comes to mind). You select one color, flush with water to clear, select the next color. Aside from that neat ability, with the pressure feed and hoses with remote paint supply it might be easier to adapt and would work "out of position" i.e. brush verticle, material horizontal. I don't know if it is still made. I think it was called "Color Changer". I wish I could give you more specifics but I haven't touched an airbrush in about 2yrs. If it's not still made you might be able to dig up a used one.

Keith

[stevenseim]

An airbrush mount for my Paasch VL is going to happen, but I've not started it as yet.

One mounting option would be to have it point down to the table of course, and that would work for large block areas, but if you remove the stop bolts on the z axis, you could just 'z' the router holder out, and 'z' in a real long one, especially if you have sufficient clearance near the end of the x axis rails. Roller mounted counterweights could use the interior of the z axis tubes as a guide. Grainger sells the gear track.

You'll need azimuth adjustments (if vertically aligned) and/or a follower to keep the brush planar, regardless of vertical or horizontal orientation. A contact that maintains a connection to one of the outputs, or a laser diode and detector, or ideally;

---planar correction built into the bots controller software!!!---

Another alternative is a vertical easel that has planar correction available through adjustments at each corner.

I'm afraid that given the manner in which the bot moves now, keeping a consistant distance from the workpiece while maintaining fidelity would be difficult, unless (once and yet again) planar correction was built into the software.

At the maximum, a plug in could table color saturation to distance from the workpiece, but as it is now, the software does not even handle long file names! oh well.

[graeme.calder@ntlworld.com]

Andrew,

I don’t have a ShopBot (but I am considering one) and therefore I’m just suggesting an idea that occurred to me reading your post.

My idea is fairly simple and perhaps requires more experimenting with the design software than the ShopBot.

First mount a single action small retouching spray gun or airbrush on the Z axis spindle or spindle mount. Next measure the full travel of the airbrush control that varies the air or paint flow from off to maximum. Most airbrushes only require a few mm of travel to do this. Next decide on a Z-axis movement (I’ll call this the “Z-control depth” for future reference) that will eventually control this movement on the airbrush control. It could be precisely that distance or some multiple of this; the latter would be better and more tolerant of inaccuracies in the linkage discussed next.

A simple linkage could be attached between the airbrush air/paint volume control and a small follower wheel running on the X rail. Any movement of the spindle mount in the Z-axis, with respect to the bridge, could cause the airbrush air/paint flow control to be operated. You will of course lose some of the X-axis travel, but just few cm. The linkage would need to have very little slack and some sort of spring tensioning – you could even make it out of hardwood using the ShopBot.

Assuming that works, the next task is to decide on a spray distance from the work piece and determine the spray width with respect to this height.

You now effectively have XY airbrush movement over the work area with the Z-control depth controlling the air/paint flow control.

Now I’m really guessing at what follows next and I’m sure many others will think of better ways or derivations to achieve what I’m about to explain.

Using a 3D software package, create vector lines for the airbrush strokes in the XY plane. Now group these and add “height” in the Z axis which will control the amount of paint to be increased or decreased. This contouring of the “airbrush strokes” must lie within the Z-control depth. A Z-axis offset for the Z-control depth from the work piece surface is the distance from work piece to airbrush nozzle. This will allow you to feather each stroke as you see fit.

I know that you are going to say that the airbrush nozzle will move further away from the work piece as the Z-axis moves through the Z-control depth affecting the spray line width. However, the Z-control depth distance is only going to be, say 1cm, compared to say 5 to 10 cm or even more for the distance from the nozzle to work piece, so there will be little effect unless you are trying to produce very fine spray patterns which require very close working distances.

Another option might be to create an image of what you want to spray and use ArtCam to create a relief from that image where the depth of relief = Z-control depth. Now add the Z offset (the distance from the work piece to the nozzle) and create a tool path. For the tool selection you would need to create a custom tool with a diameter that might equal 2 or 3 cm and experiment with cutting speeds and overlap distance. So rather that define each stroke ArtCam would produce a tool path that would actually provide colour depth rather than cutter depth.

Having said all of that I’m not sure you are going to get any real fine detail that you couldn’t get using an airbrush by hand, but what you could do is to create smooth curves and hatching patterns with feathering that no human could over large areas.

I don’t know if any of this was any help but good luck to however you guide and control an airbrush using a ShopBot.

Graeme (from the UK if you didn’t guess with my spelling of colour).