a lot of questions for acrylic/plexi

[Jensemann]

Hello all,

i want to engrave a photo on a ycrylic-plate. It's the first time i am doing sth like this, so i have no idea.

I have 1mm Ballnose and 30 degree Engravers. Think the fine engravers would be better.

So, how do i have to engrave it? "Normal" or "Inverted"?

It will be lighted with leds.

Do i need the "Light and dark area invertion" mode then?

next is about cooling: Do i need any cooling to engrave plexi?

And how to fix it without scratches? I got anti-slipmats here, those you use to mill pcbs. Will that work, or do you hold it any other way on the table?

Would be nice to hear some advises.

Thanks and nice Greetings from rainy Germany,
Jens

[RoutnAbout]

I think your best bet is to use the engraving bit, and I like the looks of the image/graphics inverted leaving the front side smooth. With the feeds and speeds set proper, the carving gets a soft frosted look.
The material I use is cast acrylic.
I think I was using between 8-9k rpms and around 2 inches per second.

[Ms Wolffie]

Hi Jensemann
As acrylic comes with a protective paper coating, do not remove it before carving. That way you don't get any scratches.
The coating is pretty firm, so you can use double sided tape to hold it down.
For photos, you carve it on the front but use inverted (not mirrored) to get the shadings right.
Make your depth of cut so that you only have about 1 mm material left on the deepest cuts.
You do not need any coolant.
Cheers and have fun

Wolffie from sunny Australia

[Jensemann]

Thanks all for the answers.

I tried it, and it went to 50% of the milling and already looked good. But then my machine started to reactivate an old Problem and lost steps in the x-axis.

Now i have to fix the machine first (although i have no idea whats causing the hangers).

But thanks so far, i keep on workin on it.

[Jensemann]

Wolffie from sunny Australia

now i see it's Australia.

I wondered why Austria should have no rain when we and France and Switzerland have

[BDM]

There are a lot of ways to do it, but I would disagree on parts of this suggestion:
"For photos, you carve it on the front but use inverted (not mirrored) to get the shadings right.
Make your depth of cut so that you only have about 1 mm material left on the deepest cuts."

While it can be cut from front or back, I prefer the back so that the front is smooth. If nothing else, it doesn't collect dirt as easily, although people always seem to want to touch it, so you get fingerprints instead . If you're lighting it on the edge, you don't want it very deep, else the light has nothing to travel through. In the example below, I only cut it a max of 0.08" on a .25" piece and still got amazing detail with the light. But I encourage you to try it a bunch of different ways and see what you like the best and how each variable affects the outcome.

Make sure you use cast acrylic if at all possible, saves a lot of broken bits and foul language.

http://www.vectric.com/forum/viewtopic.php?f=16&t=17340