Graduation Gift acrylic sign

[jimily]

Hello all,
After reading about it for months, tooling up, making a vacuum pod I have tried acrylic sign making. It's definitely stunning but I have a question about the pattern in the engraving. There are a couple of places where it doesn't look scratched like the other areas. I'll include pics.

After it comes off the cnc do you do anything else in the way of cleaning or finishing of the engraved part?

Thanks!
Jim

PS Emily is my wife

[TAW]

very nice - I can't answer your ? but I have never tried this. is this carved (scratched) from the back? and are you using a special bit? Or a new unused bit that has not touched wood?

[Keith Hodges]

Jimily, I'm no expert, but, I have done, probably a few hundred acrylics. Just a thought. Since the area is in the upper portion of your carving, looks like your clamp pressure might have been a bit tighter up there than the rest. If your table is not quite perfectly flat, the acrylic will flex with clamp pressure. Doesn't take much to show up on the carved area. Really doesn't take a lot of pressure for shallow carving, just enough to stop movement. Lots of times I'll use small pieces of wood on all 4 sides, clamp them instead of the acrylic. Use double sided tape to hold the acrylic down. Hope this helps. Keith

[roger85281]

I have some 9 x 12 pieces I purchased from estreet plastics. I was having some serious issues with one side not scratching. When I used my digital calipers on the acrylic my sheet varied by .017 from side to side. I have another 4 sheets this size. Three of them have significant variances from side to side, on just one end. All I can say is to check your acrylic. I am using a diamond drag bit, so I don't cut very deep to begin with.

[jimily]

Oops I forgot to say in my initial post --my bad...

I used a diamond drag bit 120 degree. This is an estreet plastics piece. I have not been back to the piece to clean it or anything yet as I am running towards the Christmas gift finish line and have just made it this morning at 5:08 am. We hit the road to the inlaws at 2 and should arrive by midnight. Sheesh!

The sheet was held down by a vacuum pod-I put the video of it being carved on our FB page (Jimily Farms) and you can see the upper area, and there is an area in the middle of the piece too by the nose of the Longhorn. You can see it being carved in the video and it just doesn't look the same as the other scratches as it is happening.

So I suppose we are going to chalk this up to acrylic inconsistency as my pod was a first use with a fresh flat face and the Diamond drag bit is to be more forgiving of small inconsistencies so I don't think it is those things.

Well there it is, I will know more once xmas is over and I can start fiddling around with this fun technique some more.

Thanks all, I'll post some more stuffs once ready and have caught my breath.
Merry Christmas!
Jim