MadModder

The Shop => CNC => Topic started by: John Hill on February 17, 2022, 11:17:38 PM

Title: CNC painting system, another silly idea?
Post by: John Hill on February 17, 2022, 11:17:38 PM
I have spent some time trying to paint roadsigns on my CNC table.

The first run was OK,  I used regular permanent markers to outline the letters then we 'coloured them in'.

The second run was a disaster because the solvent in the markers softened the base paint that then blocked the marker tips,  tips were munted and the painted base surface spoiled.

So I mounted an airbrush and that looked quite promising until the cheap airbrush showed it's true colours.  It would paint well for about 45 seconds then stopped painting,  it would restart after cycling the needle movement but that also left an unacceptable splodge of paint on the work.  There were hard to stop air leaks and when trying to solve these by tightening the screws the seals ruptured then the threads showed signs of having stripped and the whole airbrush was worth nothing more than a resting place in the skip.  I will not be buying another airbrush until I am certain that would be money well spent.

Meanwhile I am looking for a pen that won't block up,  a spray that will work and not fall to bits or something else that will paint my lettering on the sign boards.
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on February 18, 2022, 12:27:03 PM
I'm drawing a blank, john, so far about the lettering paint, but am wondering if you could change your base paint to be resistant to the marker solvent.

Markers, I believe, are in the alcohol/acetone solvent class. If base paint is in the oil or polyurethane class then they should not affect each other.

Alcohol/acetone class paints include shellac, lacquer, lacquer type automotive finishes, and Krylon (tm) so I would avoid using those with markers.

Oil based class paints would be the oil enamels, alkyd oil enamels, polyurethanes, and those should not be affected if really dry. Particularly polyurethanes, which have a very high resistance to solvents.

I don't know how markers would affect polymer/acrylic latex water cleanup type paints. Might or might not play well together with markers.

I guess a polyurethane enamel would be my choice. Or you migh consider overcoating any kind of base paint with a clear polyurethane varnish before applying lettering.
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on February 18, 2022, 02:10:53 PM
Thanks for the paint information.   The base paint on the problem board was a water soluble acrylic with a faint 'chemical' smell,  it took days to dry and I think it was still somewhat soft after a couple of weeks.  The pens were CRC brand paint pens.  I did not try to fill in the lettering with these pens.

I was so disheartened by my airbrush experience and became determined to give them another go so I have ordered another.  I also found advice that simple beeswax can be used to control the air leaks that gave me grief and led to the damage to the first airbrush.  Air brushing has the potential to totally fill the lettering which pens can not really do.


Meanwhile, other members of our museum volunteers have painted more boards for me to do the lettering.  They have used acrylic paint which the tin says is suitable for exterior use, new paint bought for the purpose, unlike the other paint which was really unknown properties and found in our store.




Title: Re: CNC painting system, another silly idea?
Post by: WeldingRod on February 18, 2022, 05:19:53 PM
I've seen pens that are airbrush paint reservoirs...  blo-pen, maybe?

Sent from my SM-G715A using Tapatalk

Title: Re: CNC painting system, another silly idea?
Post by: John Hill on February 18, 2022, 07:51:40 PM
They might be interesting!
Title: Re: CNC painting system, another silly idea?
Post by: JerryNotts on February 19, 2022, 08:40:57 AM
After more years than I like to remember much of that time spent in coating industry labs. in the UK, I can no longer resist trying to offer you some remarks on misconceptions about the nature of the various formulations of inks and paints.

1. Both paints and inks can usually be divided into three main groups a) air drying eg decorative paints as you would use at home, inks for ball point pens etc.  b) 'Stoving' paints and inks, tin cans have examples of both, base coats applied by rollercoating and printing inks applied by a printing press. Many other industrial items are 'stoved'. c) Powder eg the toner in a laser printer, or the paint used nowadays in pipe manufacture . These examples are not exhaustive.

The signs you are trying to produce would normally be screen printed. Look up the process on Wikipedia. The inks have if intended for air drying, until recently been based on NC  and containing some fairly strong solvents such as ketones and/or esters.

Your main problem would seem to be preparing suitable screens for the images which you want. This is the expensive part of the job. Once you have the screens and a suitable ink (the principle property is the pasty viscosity) for the surface you want to print on, the rest of the items can be made at home. Screen printing is almost a cottage industry, only those that have contracts from for example the Highways agency or from motor manufacturers ( dash board instrument graphics) are well set-up.

I have never seen sprayed graphics give a decent result.

There are some on-line suppliers of screen printing materials, maybe it would be worth while speaking to them.

I don't want to be 'wet-blanket' but I hope this might set you off in the right direction.

Jerry
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on February 19, 2022, 09:40:58 AM
John just a silly thought but if the new airbrush doesn't work out, what about possibly making your own paint marker type brush with some hard felt and an open tube reservoir?
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on February 19, 2022, 02:14:15 PM
Thanks for the information Jerry.

As nothing is yet off the table completely I may end up screen printing but at this time that is a dark art to me. Nonetheless, in the future maybe.

There seems to be a delay in the delivery of my second airbrush and after a period of cogitation I am now considering a brush system. 

A small paint brush mounted on a mechanism so that it can be lowered to contact the work or raised and dipped in a shallow container of paint.  The mechanics are not difficult but integrating it into the CNC-GCode system caused me to lay awake for a while when I should have been sleeping. 

There is limited scope for tapping into the Arduino-GRBL but there are pause and reset pins plus a second Arduino which was set up for the airbrush.  I will put software on the second Arduino to at intervals pause the machine motion and cycle the brush through Up-Dip-Down then restart the machine.


Hmmm...this is MadModders after all. :lol:

 
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on February 19, 2022, 05:25:15 PM
 :proj:

That's the spirit!
Title: Re: CNC painting system, another silly idea?
Post by: tom osselton on February 19, 2022, 07:01:41 PM
[That sounds like a scene from the movie Hugo

A small paint brush mounted on a mechanism so that it can be lowered to contact the work or raised and dipped in a shallow container of paint.  The mechanics are not difficult but integrating it into the CNC-GCode system caused me to lay awake for a while when I should have been sleeping. 
[/quote]

Title: Re: CNC painting system, another silly idea?
Post by: shipto on February 19, 2022, 08:43:04 PM
Could a printer be sacrificed to help?
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on February 19, 2022, 08:45:31 PM
I think the stepper motor I am using for the brush is from a quite old IBM line-flo printer! :beer:
Title: Re: CNC painting system, another silly idea?
Post by: shipto on February 20, 2022, 05:59:15 AM
I was more thinking the print head being used to outline  :lol: but probably going to be slow.
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on February 20, 2022, 01:11:59 PM
I was more thinking the print head being used to outline  :lol: but probably going to be slow.

Now that is an idea...................... :coffee: :coffee:
Title: Re: CNC painting system, another silly idea?
Post by: hanermo on February 22, 2022, 11:17:48 AM
Fwiw..
Now re/painted all 240 parts for the cnc with yacht quality outdoor epoxy paint.
And the outside main house door, metal, 5.6 x 2.3 m, both sides.

Using a shiny, glossy, 2-part epoxy paint, and a proper 50 l low-speed conpressor, and a proper industrial paint gun.

Results are absolutely fabulous.
Fully automotive/yacht quality.

The downside is that the paint gun was 90,
compressor 190 on clearance sale,
and the paints are 35 each l, now about 8 l  in..

Also painted the steel I beams that the new sauna will rest on, 3 coats, and they look totally fab.
Foundation beams, that bolt to concrete slab via 316LSS rods and nuts.
5.8 m long x 160 mm tall, IPN profile I beams.
We ground it to shiny white metal first, then painted immediately.
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on February 22, 2022, 03:16:49 PM
Sounds pretty!  :clap:

um, but this thread is about the machine doing the painting.  :)
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on February 22, 2022, 09:06:56 PM
I spent all day yesterday working on a futile arrangement of MDF discs and wires (fishing trace).  The MDF material was totally unsuitable and the trace wires would not play the game.  So I pulled it all apart to salvage a few bits and start again.


(https://thumbs2.imgbox.com/65/8f/LP4QvjBP_t.png) (https://imgbox.com/LP4QvjBP)

Version two will have sprockets and chain to keep the moving arms synchronised.
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on February 22, 2022, 10:53:01 PM
Suggestions: sliding glass door track pulleys, and fine stranded coated bead cable available at craft stores/places that sell beads for stringing into necklaces.
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on February 24, 2022, 01:20:30 PM
Thanks, I will keep that sliding door hardware in mind.
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on March 21, 2022, 01:20:28 AM
 I have not abandoned this project, not yet anyway! Right now I am battling poor quality stepper drivers.

The John Deere stepper had only limited travel and is put aside for the time being....

The brush dipping mechanism has been knocked up and the basic movement is OK, I just have to get the stepper driver to do it's assigned function..

(https://images2.imgbox.com/53/93/zX24bbj2_o.jpg)

When the chain is routed around the motor pinion the three cranks move and the potentiometer driven by the fourth sprocket will limit the travel to about 200 degrees left or right.

A board over the three cranks will carry the paint brush. At one end of the travel the brush will be on the work and at the other it will dip in a paint cup.

The brush will be attached to a vibrator for a quick shake to release excess paint as the brush rises out of the paint and a more gentle shake while painting to encourage consistent paint flow.

Well, that's the plan anyway!!:)
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on March 21, 2022, 08:30:47 AM
Great stuff, John! I always really enjoy your style of making things.  :coffee:
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on March 21, 2022, 02:38:26 PM
Great stuff, John! I always really enjoy your style of making things.  :coffee:

Errr...yes, I agree it does look a bit rumpty!   Maybe if it works I might build a 'production' model with sheet HDPE (and using a set square). :D
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on April 20, 2022, 12:47:48 AM
(https://thumbs2.imgbox.com/5d/9a/kCD8sMkg_t.jpg)

Peristaltic pump proof of concept, works too!
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on April 20, 2022, 01:24:12 AM
Hmmmm.........that's interesting,  the image hosting site says the image has been banned...

Try this link   https://home.mycloud.com/action/share/cc3ebf9d-058e-45fc-97eb-46941d7a511c (https://home.mycloud.com/action/share/cc3ebf9d-058e-45fc-97eb-46941d7a511c)
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on April 20, 2022, 08:28:18 AM
Fixed the second link, John. The first link said the image was not found.

Cool pump BTW!  :clap:

Title: Re: CNC painting system, another silly idea?
Post by: ddmckee54 on April 20, 2022, 10:52:38 AM
This almost sounds like the HP pen plotters that we used 30 odd years ago.  They made a mess of the paper when an area was gone over more than once.  That might be something to keep in mind with your project.
Title: Re: The pump at work
Post by: John Hill on April 21, 2022, 02:47:53 AM
https://home.mycloud.com/action/share/d9ab60b8-dfc7-4ea4-b849-233308b4862c

....this is at 10rpm and the slowest I can go (without fudging the software) is 1rpm and then there are almost two drops per minute.

John
Title: Re: Testing!!!!
Post by: John Hill on May 11, 2022, 05:06:54 AM
Here is a link to a couple of pictures and one video of my sign painter project..

https://home.mycloud.com/action/share/c25d9813-83db-41f0-aa3a-7e321b8a87a3 (https://home.mycloud.com/action/share/c25d9813-83db-41f0-aa3a-7e321b8a87a3) :ddb: :ddb:
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on May 11, 2022, 08:20:47 AM
Wow, John, I love the rotary brush idea -- well the whole thing. What I like most about your projects, besides the fact that they work and use all kinds of scrap materials, is that they are also fun. You design fun into machines!  :beer: :clap: :clap:
Title: Re: CNC painting system, another silly idea?
Post by: awemawson on May 11, 2022, 09:25:22 AM
If I follow the link I get dire warnings of impending doom  :bugeye:

Title: Re: CNC painting system, another silly idea?
Post by: John Hill on May 11, 2022, 03:23:38 PM
If I follow the link I get dire warnings of impending doom  :bugeye:

Bother!  I do not have an answer for that. :doh:
Title: Re: CNC painting system, another silly idea?
Post by: kayzed1 on May 11, 2022, 03:27:57 PM
same here to.
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on May 11, 2022, 03:36:50 PM
I am considerably angered by the red box which obviously does not show in some browsers. 

If you want to live dangerously you can click on the 'details' button and read what they have to say then continue on to see my pictures anyway. :Doh:
Title: Re: CNC painting system, another silly idea?
Post by: awemawson on May 11, 2022, 03:43:45 PM
I crossed my legs and fingers and went ahead . . . . . . are you sure it's not a dialysis machine you're making !
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on May 11, 2022, 03:50:16 PM
Seems the red flag is a Google "service" and does not appear under Microsoft Edge.
Title: Re: CNC painting system, another silly idea?
Post by: vtsteam on May 11, 2022, 05:52:14 PM
Works fine in Firefox.

Sorry but, fact of life in FutureWorld: If you guys are going to stick with Google Chrome, eventually the only content you'll see is Google's own content.

Funny thing is, that site has Google's Tag Manager running on it as a hidden script. Talk about the pot calling the kettle black!  :)

Seeing a big red screen of warning, at first you'd think your computer would blow up if you visit John's simple download page. But here's what it actually says the danger is that elsewhere the site might include software intended to:

"harm your browsing experience" by "tricking" (convincing?) you into a change of homepage, ie away from Google's homepage in the Chrome browser. Possibly by promising some free benefit...... and it might then serve up additional non-Google' originated ads.

This is of course what Google itself does -- practically every site on the net has hidden background Google tracking software running on it, called scripts, and many ads you see elsewhere, including constant ad interruption of YouTube are originated in that personal profiling.

Well, that's it, the entire danger. No mention of malware, no viruses, no phishing, no fraud. Just the possibility of deflecting Google's ad revenues. A red screen, Google can now apparently block content for 2.6 billion Chrome users on any site it chooses citing"harm to browser experience" "Browser experience" is the long standing code phrase for Google's own user tracking and ad injection.

Ah well, who cares......
Title: Re: CNC painting system, another silly idea?
Post by: John Hill on May 11, 2022, 06:01:35 PM
Thanks Mr Steam...

The brush paints a 22mm wide path which may be fine for the intended use of painting roadside signs but I may have to find a way of trimming the brush down,  fortunately I bought a box of 30 of those brushes!  China of course.