What is the best bit for drilling clean pockets in clear acryllic (size, type) ?
There are videos on cutting acrylic at:
best practice is to use a smaller tool (single flute) and machine as a pocket, ideally leaving a roughing clearance and taking a finishing pass.
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I tried to use a 1/8" Nomad 101 at 10.000 rpm, it works, but it makes small “lines”. Using a bigger tool did not work, and tore up the acryllic surface.
The 101 is a ball mill, so it’s going to leave scallops. Reducing the stepover will help, but there will always be a scallop.
As Will mentioned the single flute (O-flute) bits work very well. Slow rpm, fast feedrate.
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Thanks. Name of 1/8" single flute O-bit ?
Where to buy Carbide #274Z in EU (or US without insane shipping cost) ?
Please write in to sales@carbide3d.com — they should be able to put you in touch with an EU reseller.
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I tried some cheaper CNC bits for plastic - Major mistake. First it drilled nice and precisely without significant scallops, but then it started accumulating hardening acryllic on the drill bit repeatedly (even with lowest RPM and the dustboot at full suction) and ruined the cut.
Waiting for some Carbide #274Z to arrive.
I have not tried them all, but this brand has given me good results all-round.
https://www.aliexpress.com/item/1005006499765978.html
If you want a tiny bit less anxiety for crashing but not compromise on quality.
Go as fast as possible as mentioned above.
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Thanks. What RPM did you use and how did you avoid melted Acryllic accumulating on the drill bit ? My problem is that the slowest speed with the Dewalt router is 16000 RPM.
You shouldn’t get melted plastic if you are cutting cast (not extruded) with feeds and speeds appropriate to that material and the tooling you are using.
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Ole, must be a “O”-Flute (letter “O”, not the number zero), lowest RPM, and fast speed should make it. With extrusion acrylic remove the cover plastic sheet first, that always makes a mess on the bit, with cast acrylic -the one with the paper protection- that cover may stay, but IMO it is better also to remove that. It is always recommended to rather use cast acrylic, little more expensive, but has a slightly higher melting point. I recently used up some leftover extrusion acrylic (because I could get it in the hardware store, cast acrylic is usually not available in regular hardware stores) and had good success with 8000rpm, and fast speed. And: a spindle is recommended. I had at least 3 broken brushes as far as In remember, possibly more since I have 4 routers in my cabinet, one even after very few weeks, sure, can be easily repaired and/or returned, but the damage in the stock is already done when the router all the sudden stops routing… Spindles are brushless, and made for endless hours of work (handheld routers are naturally not). And spindles are much, much easier to work with: no switching on and off, no manual speed setting etc…
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maxed out at 3800mm/s usually.
Also had some luck soaking the acrylic sheets in WD-40 when using small cutters.
It is usually game over when it starts globbing up the end mill.
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I only need to make pocket lines in two acryllic plates (25x30 cm) for assembly guidance for a loudspeaker and I have already ruined 2 plates. Maybe I should just look for a place to have this done ?
I think it depends on how valuable your think this knowledge could be going forward. If it’s just a one off and you’re not working with the material much (and don’t plan to) then outsourcing seems appropriate.
Though it’s pretty safe to say it can be done successfully on your machine. So if doing this kind of work in house seems particularly valuable, you can certainly figure it out.
And as much as it stings to say it, those two ruined sheets provide you a lot of material to practice with and get things dialed in.
Then there’s the in between approach of outsourcing this job to relieve any time pressure and working away at figuring things out at your own pace afterwards. There are some materials I’ve worked with that take months of tinkering every few weeks before landing on an approach I like…I’m still not happy with my pure copper milling 
One other note is the spindle vs router thing. Maybe it’s worth investing in a spindle to give yourself the flexibility of working at these material extremes more easily? Probably not something you want to block a project on but maybe the next time acrylic rolls around you can have a spindle with a much lower min speed. (I think it’s still doable with a dewalt router but lower speed certainly wouldn’t hurt things)
Plus you get all the benefits that Emmess pointed out. The quality of life improvement alone is pretty considerable.
Regardless, I’m following along to see how it turns out. That’s looking to be an awesome speaker and I might be getting into much more acrylic myself in the coming months. Good luck 
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Thanks for your encouraging words. The speaker unit holes are easy with the powerfull laser cutter and looks perfect. Wish I could make the pocket lines the same.
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