HDPE

HDPE - a lightweight, inexpensive plastic that's great for CNC milling

What is HDPE?

HDPE stands for high-density polyethylene. It’s an inexpensive, lightweight, chemical-resistant, food-safe plastic that has a high strength-to-density ratio, which makes it well suited for a vast number of applications. It can be blow molded, injection molded, and extruded. You may recognize it as “#2 plastic” by its recycling symbol.

What is HDPE used for?

HDPE is used everywhere in our daily lives: milk jugs, plastic bottles and containers, bottle caps, food-storage containers, plastic bags, the inner lining of TV cables, sewer pipes, swimming pool liners, fuel tanks, toys, landfill liners, 3D printer filament, and even the frame of the Othermill!

Othermill users mostly employ HDPE to make custom fixtures. When you want to make the same thing multiple times, a custom fixture can increase accuracy and significantly reduce the time it takes to attach your material to the bed.

Is HDPE safe?

Yes! Of course, don’t poke yourself in the eye with it, and don’t burn it and inhale the fumes.

Where can I get HDPE?

We sell precut pieces of HDPE in our store! They’re the perfect size for many Othermill projects and fit nicely on the Othermill bed. You can also order it from various plastic suppliers.

Fixturing: How do I attach HDPE to the bed of my Othermill?

Nitto Permacel P-02 tape is the best option for new and intermediate users, with hot glue as an alternative if you don’t have that tape. We have guides for both tape and glue. Advanced users or adventurous intermediate users should check out our guide to bolting your material to the y-bed, which provides an extra level of strength and rigidity.

What endmill should I use when milling HDPE?

In general, larger tools like 1/8" and 1/16" flat endmills are better because they cut through material the fastest and are least likely to break. If you’re making a custom fixture, a 1/8" flat endmill is your best friend. For 3D shapes, a 1/8" or 1/16" ball endmill produces the smoothest contours.

For best results, keep a set of endmills specifically for HDPE and other plastics, and never use them to cut metal or PCBs. This will allow for increased milling speeds and a better finish.

What are some example projects?

Custom Fixture for the OtherYo Project hdpe1

The Othermill Frame hdpe2

Note: The feeds and speeds below are optimized for the V2 Othermill. If you are using an Othermill Pro or Kickstarter Othermill, you may need to experiment to find optimal settings.

Recommended Feeds and Speeds

Download The Custom Tool Library for HDPE
To make it easier to use these recommended feeds and speeds, we’ve created a way for you to quickly import into our software all the settings you see listed below. To do this, first, download this file, which contains all the recommended feeds and speeds for this material. Then open our software, click File > Tool Library, click the “Import” button, and select this file. Before using these settings, it’s a good idea to read through our Feeds and Speeds Guide.

Download the Custom Tool Library here.

Tool: 1/8" flat endmill
Feed rate: 23.622 in/min (600 mm/min)
Plunge rate: 1.575 in/min (40 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.008" (0.21 mm)

Tool: 1/16" flat endmill
Feed rate: 23.622 in/min (600 mm/min)
Plunge rate: 1.575 in/min (40 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.009" (0.23 mm)

Tool: 1/32" flat endmill
Feed rate: 23.622 in/min (600 mm/min)
Plunge rate: 1.575 in/min (40 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.010" (0.25 mm)

Tool: 1/64" flat endmill
Feed rate: 23.622 in/min (600 mm/min)
Plunge rate: 1.575 in/min (40 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.003" (0.08 mm)

Tool: 1/100" flat endmill
Feed rate: 23.622 in/min (600 mm/min)
Plunge rate: 1.575 in/min (40 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.003" (0.08 mm)

Tool: Engraving bit
Feed rate: 39.370 in/min (1000 mm/min)
Plunge rate: 1.575 in/min (40 mm/min)
Spindle speed: 12,000 RPM
Max Pass Depth: 0.003" – 0.020" (0.08 mm - 0.5 mm). Keep in mind the engraving tool has a variable width, depending on your “engraving cut depth.” The deeper the cut, the wider the tool. The shallower the cut, the narrower the tool. If you’re using an engraving tool and the generated path isn’t cutting part of your .svg file, try reducing the engraving cut depth.

Advanced Feeds and Speeds

Warning: These settings are for advanced users. Before using any of the information provided here, you must read the section above on fixturing your material. The feeds and speeds specified here are more aggressive (and thus faster and more fun), and improperly fixtured material can be knocked loose and damage itself and your machine.

Tool: 1/8" flat endmill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 19.6 in/min (500 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.02" (0.5 mm)

Tool: 1/16" flat endmill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 19.6 in/min (500 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.02" (0.5 mm)

Tool: 1/32" flat endmill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 19.6 in/min (500 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.02" (0.5 mm)

Tool: 1/64" flat endmill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 19.5 in/min (500 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.01" (0.25 mm)

Tool: 1/100" flat endmill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 19.6 in/min (500 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.005" (0.13 mm)

Tool: Engraving bit
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 19.6 in/min (500 mm/min)
Spindle speed: 16,400 RPM
Max Pass Depth: 0.003" - 0.020" (0.08 mm - 0.5 mm). Keep in mind the engraving tool has a variable width, depending on your “engraving cut depth.” The deeper the cut, the wider the tool. The shallower the cut, the narrower the tool. If you’re using an engraving tool and the generated path isn’t cutting part of your .svg file, try reducing the engraving cut depth.