LED neon-looking sign in acrylic

[swallace84]

Hope y'all are well. A local LED shop is asking me to make a sign for them. I would just be doing the cutting on the cnc. The LED shop would be doing all the lighting and wiring. The sign would say something like 'we make custom signs' and it could be the start of a business relationship. He wants something like this about 4 foot by 4 foot:

https://www.etsy.com/listing/9864034...gnwedding-name

I've never really cut acrylic before. Regal Plastics here in the Austin area sells a cast acrylic 3/16" 4x8 sheet for about $200. The client says he wants something less than 1/4" thick.

Clear, cast acrylic is what I want for this type of job, correct? Not extruded?

These tools would work well, correct?

https://www.toolstoday.com/v-13351-51404-k.html
https://www.toolstoday.com/v-14988-57361-k.html

I suspect he'll affix the LED flexible strips on the surface in the grooves that I cut out. I don't think he'd do it on the back (as I've seen in some youtube videos) because the material will be so thin.

Anything else that I should be thinking about as I plan out the cut? Details I need to get out of the client? Using the blackbox hurricane vacuum would be good for this type of job, correct?

many thanks and all the best

[Charlie_L]

I haven’t cut much of this plastic but single o flute is the way to go. Don’t turn the spindle too fast. Watch for melting plastic. Notes I’ve collected read ——-

Cast Plexiglass

3/16 O-flute, 1/2 inch material, 18,000 rpm, 90 ipm spiral ramp with 0.0625 inch per pass

———-
Seems likely your tool choices will work well. Given the uncut tools and thinner material the vacuum hold down will be very helpful.

[Xray]

Not getting the concept here, so channels are cut in the plexi and neon lighting is form fitted to them ?

In any case any good sharp endmill should do, speeds up and RPM's down [to minimize heat buildup] I've tried optimized plastic bits, really never noticed anything special about them but hey, maybe I'm missing out. I've cut loads of plexi but nothing close to that size [would dwarf my table] ,, And thinner stuff can be trickier than thick. For .25 you might want to try 2 passes, even 3 but I would think 2 should suffice.
Best to practice on a scrap piece if able, doesn't need to be large. Upcut bit to my mind may cause uplifting of the sheet if it runs into any unsecured areas, so be careful of that, that could potentially ruin the whole sheet. Might be fine on the edges, I'm wondering how it will do when it gets further from the secured edge. Even a little uplift would probably cause chatter in the plexi.

Cast, yes ,, Gotta say, have never seen any extruded, anywhere.

[tmouse]

You may want to cut on the reverse side and they may use edge lighting to get that effect.

[swallace84]

Thanks y’all! Really appreciate it. After talking with the client again, sounds like we are going to go with .2” cast clear acrylic. Since it’s so thin, there won’t be grooves / channels. He says he can affix the led strips without grooves / channels. I guess with glue.

He needs a guide though as to where to put the led strips. The sign will say something like ‘we make custom signs.’ Right now, I’m thinking I can type that out in a nice font in vcarve pro, then use a vcarve toolpath at a super shallow depth. That way I’ll have the centerline if the text. But instead of actually using a vbit, I use a diamond drag bit after making sure I change the gcode so the spindle doesn’t turn on (how do I do that?).

Am I missing a better way to do this? Finding a centerline in non uniform text is confounding me otherwise. Thanks!

[Charlie_L]

I typically edit my gcode file making sure there is NO command to turn on the Spindle (M3). Maybe add another M5 to turn it off? Plus I typically pull the plug on the Spindle because it is easily removed.

Have you looked at single line fonts?

[gtgmarine]

I've made a couple of edge-lit acrylic signs - it's pretty simple and I've shown a few of the ones I've made below.
Thinner acrylic works but I like to use 1/2" if possible because most LED strips are about 1/2" wide. I prefer to make a base that houses and hides the LED strip and also supports the sign.
As for engraving the acrylic, I just use a 90 degree V-bit. You don't need to go deep - a tenth of an inch is plenty.
On the blue sign I used a simple VCarve while on the red one I used a small 1/8" upcut O-flute end mill and pocketed the letters and palm tree.
On that piece I also used a frosted back which is a little different.
I suggest you do some testing on some scrap pieces to get the look you want.
20230115_181331.jpg
20221111_110614.jpg
Have fun!

[swallace84]

Thanks y'all. Charlie, I'm embarrassed to admit I hadn't thought of single line fonts. Thanks so very much. Really appreciate y'all being able to help point out obvious solutions :)

Additionally, I did find a solution to my problem for non-single line fonts. Looks like I'd need to use inkscape (which is free) and then use Hershey fonts. This video sums it up nicely.

https://www.youtube.com/watch?v=_2_d8s3dgr0

[Devilfish Tech]

Cutting acrylic on a CNC can be a real pain. The hold down was a real chore and as mentioned, can easily ruin the entire piece. It was the biggest reason for me to get a gantry CO2 Laser specifically for acrylics.

Part of the problem with acrylic, is that it shows every little scratch. I would be cautious of just applying a single center line scratch. Might want to test that it with their application. In my experience, it is better to do all of the lettering or none of it.

The other option is to cut a template out of something else (1/8" ply or paper if you have the diode laser) and allow them to follow that.

Hope this helps!

[gtgmarine]

I cut acrylic almost exclusively with no problems... but I use vacuum. I agree it would be a real pain without vacuum hold down.

[swallace84]

I think I finally found what I was looking for.

https://www.youtube.com/watch?v=wuy6Ry_xmRU&t=1s