Getting Panels Engraved?

[JohnB]

Grr this forum ican be so frustrating!!

Just typed a reply only to lose it as the forum is too busy....It says it saved it but lord knows where!!!!

Ah well now.... yes .....
I entirely agree that white over clear and grey over white is the proper engineering way to go. But in my experience while the laser is incredibly accurate in the x/y axis its pretty grim on the z axis... The slightest change in tube temp or air assist or just about anything happening within 40 miles changes the intensity of the beam results in areas of white being completely removed or grey not being removed...How did you get that accuracy..more white paint?.. (I did try that but got differing back light intensity)...I find with the exact same settings even ambient temp affects the power.

Whats the secret??????

John

[m0ng00se]

Whats the secret??????

John

I also tried paint first, but that didn't work for me, so I had to come up with a way of getting a thin white layer on top, so my secret is plasticard. I used 0.25mm on the existing panels, but I measured the real panels and they are 5.52mm, so I will be using 0.5mm plasticard on 5mm clear acrylic next. Even the 0.25mm gives you plenty of leeway in terms of the "Z-axis" on the laser. Sometimes, I find some letters are not very crisp or all the way through the paint, then I just select those letters and run the laser again. 0.5mm plasticard will even give more leeway. Works a treat !! Try it, you won't regret it Plasticard on ebay is dirt cheap, clear acrylic is cheap, you've got the paint and that's it. Much better than opal in my opinion

This was my very first test panel using this method. Don't worry too much about the backlight photo, again this was just tested with a single amber 5mm LED, hence the little unevenness.

11021489_10152538904821735_7986225606237085674_o.jpg

Then put it in your cockpit, used and abuse the **** out of it to make it look dirty the way you like it

[JohnB]

Ah getting better prices !
can you bond it to acrylic with the acrylic cement (the Chloroform type stuff?)

John

[m0ng00se]

John,

After the panel is machined (or probably cut in your case), I put it face down on a sheet of plasticard and then apply Tamiya Extra Thin Cement with the supplied little brush just around the edges. It's like water and bonds them quite well together. Then just a sharp knife and fine grit sandpaper to finish it off before I spray paint it.

[Zlatko]

Hi Guys,
What sort of primer you are using to prepare Plexiglas surface.
And then – what paint – Acrylic water soluble, Acetone soluble? Or Epoxy Enamel based. I am totally lost.

[m0ng00se]

I just use Hycote White Plastic primer, then I use a black matt layer as a light blocker, then acrylic for the top coat. I tried cellulose before, but it doesn't engrave so well with my laser.

[JohnB]

HI Guys

I spray cellulose matt.... no primers needed!


John

[Zlatko]

Thanks a lot. I’ll give a try to both methods.
Recently, I used unknown primer for plastic plus unknown black paint (water soluble),
I bought them from a shop selling car paints. Left it to dry 3-4 days and when I swept the surface with a damp cloth, the paint started to come off and the surface became stained. I suppose that is not normal.
Most probably I am a bad … bad painter ...
PS- John, when you say cellulose matt, is that nitro-cellulose spray for cars?

[Zlatko]

Thanks a lot. John, when you say cellulose mat, is that nitrocellulose spray for cars ?
I'll give a try to both methods. Few days ago , when i first painted a piece of Plexiglass, i used unknown primer and
unknown black paint which i bough from a shop selling paints for cars. And i left the panel to dry 3-4 days. Then i swept the surface with a damp cloth and the paint started to come- off. I suppose - that is not the way it should be and i am a very bad painter

[JohnB]

Hi Zlatco
yep thats the stuff.....
My local place also makes it up into spray cans..very convenient but its like x5 the price.

you can engrave it after about an hour careful though its soft still then and you can leave thumbrints etc..BUT a scouring pad with LOADS of soap and a light touch can often get rid of mess ups.

Spray straight onto the acrylica when you have removed the film (and of course all the dust that sticks with static) do NOT sand the acrylic to get a key as with some thinners the finish can "pickle"..straight onto the sheet work just fine.

If you are using a laser... I now tape the sheet in place cut all the cutouts and outer shape, lift it out, spray the whole thing, leave an hour, pop it back into the cutout and then run the engrave ! nuch nicer finish I have found.

John