[300INDUSTRIES]

I am trying to engrave some lettering into 1" acrylic (and I am 95% sure that it is cast acrylic) but everything I have done turns up clear or maybe slightly milky. I am trying to get a nice white uniform frosted look on the engraving. I've tried both cast and extruded acrylic (the extruded was a messy molten disaster!). For the image attached the specs are as follows:
Bit: 1/16" solid carbide one-flute down cut super O flue (Onsrud 64-000) --for the size of the lettering I need to at least have this small of a bit for the outline
Feedrate of 30in/min and an rpm of 14000, engraved at a depth of 0.115 in two passes.

Does anyone out there have advice for how to achieve a white frosted finish?
Thank you!

[bostosh]

Try 150 grit papers

[300INDUSTRIES]

Interesting job! Yes, I had achieved a similar effect when I had taken a pneumatic diamond tip grinding bit to a larger engraving after the fact but these letters are only about an inch tall; far too small to really get in there with sand paper. Whenever I see videos of people routing cast acrylic the routed lines look a whole-lot more frosted than what I've been able to achieve. I was wondering if there was a specific bit or cut strategy I needed to learn. I would much prefer not having to sand-down these small letters after the machine routes them, unless that is the only way to achieve this white frost effect. I am attaching a close-up of the sample I had cut (transparent) and the sample I am basing my work off (frosted white). Does anyone know of a specific bit/speed I need in order to achieve this frosted white look or does this look like the work of post-production sanding?
Thanks!

[Gary-Wiant]

This is an interesting thread I'm hoping to learn what you figure out.

[skywalker4]

have you considered bead blasting the entire pc and then engraving the letters, get the opposite effect?

[300INDUSTRIES]

That's an interesting idea, and I suppose since the contrast between piece and lettering would be the same it would work, however I am trying to recreate a sample that was given to me by a hotel, so I need to have the lettering frosted. I am not familiar with bead blasting...would it be something to where I could cover the whole piece (minus the lettering) in painter's tape to achieve the frosted look on the lettering?

[skywalker4]

It is a much finer powder than sand blasting, i think its the look your going for. try a sample piece and see if the tape holds, its worth a try.

[Gary-Wiant]

I doubt the tape will hold up great especially in the real fine areas, unless your hitting it fairly lightly, but it is a good idea.

I'd start with either doubling up Intermediate vinyl or if that doesn't work try sandblast mask, but that would get expensive and I'm not sure how good it would route.