FR-1 (Circuit Boards)

Store-Material-PCB-DoubleSided-10

What is FR-1?

FR-1 is a hard, flat material that consists of a thin layer of copper over a non-conductive phenolic resin. It’s usually about the thickness of two or three credit cards.

What is FR-1 used for?

FR-1 is primarily used for making circuit boards. The thin copper layer can be milled or etched away, leaving traces to which electronic components can be soldered.

Is FR-1 safe?

Unlike FR-4, which is fiberglass-based and generates dangerous glass-shard dust when milled, FR-1 is safe to use if you keep it away from your eyes, lungs, and skin. We recommend vacuuming up the debris after you’re done milling (never blow on it).

Where can I get FR-1?

We sell it in our store. It’s generally hard to find in small quantities elsewhere.

What’s the best way to fixture FR-1 to the bed of my Othermill?

Attaching your board to the Othermill bed is called fixturing. The easiest way is with tape. Place strips of double-sided tape across the back of the board until most or all of it is covered with a single, even layer of tape, without any overlap. We recommend Nitto Permacel P-02 tape. Scotch Permanent Double-Sided Tape will also work in a pinch, but Nitto tape is the most reliable.

Once you’ve applied tape (before sticking the board to the bed) we recommend measuring the thickness of your board with digital calipers, including the tape. Then, enter the thickness into your material setup. This will prevent accidentally cutting too deep.

It’s also good to check if the board is bowed (in both x and y directions), and then gently bend it back the other way until it looks straight. This will help make sure the board lies flat, which is very important when using 1/64" and 1/100" end mills.

FR1 1

What end mills should I use when milling FR-1?

Most circuit boards can be milled with 1/32" and 1/64" flat end mills, but occasionally 1/16" or 1/8" flat end mills can be used if you need to remove large sections of copper. For very tiny features, like the pads on TQFP chips, you’ll need to use a 1/100" end mill. Check out our surface-mount package compatibility page for more info.

What are some example projects?

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

Note: These feeds and speeds are used by default in Otherplan, and are provided here as a reference.

Tool: 1/8" flat end mill
Feed rate: 14.173 in/min (360 mm/min)
Plunge rate: 1.81 in/min (30 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.005" (0.13 mm)

Tool: 1/16" flat end mill
Feed rate: 14.173 in/min (360 mm/min)
Plunge rate: 1.81 in/min (30 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.005" (0.13 mm)

Tool: 1/32" flat end mill
Feed rate: 14.173 in/min (360 mm/min)
Plunge rate: 1.81 in/min (30 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.006" (0.15 mm)

Tool: 1/64" flat end mill
Feed rate: 5.669 in/min (144 mm/min)
Plunge rate: 0.472 in/min (12 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.002" (0.05 mm)

Tool: 1/100" flat end mill
Feed rate: 5.669 in/min (144 mm/min)
Plunge rate: 0.472 in/min (12 mm/min)
Spindle speed: 12,000 RPM
Max pass depth: 0.002" (0.05 mm)

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 improperly fixtured material can be knocked loose and damage itself and your machine. FR-1 needs to be completely flat, or else 1/64" and 1/100" end mills will break when they encounter part of the material that is sticking up. BitBreaker Mode must be enabled in order to change your feeds and speeds.

Tool: 1/8" flat end mill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 15 in/min (381 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.006" (0.15 mm)

Tool: 1/16" flat end mill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 15 in/min (381 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.006" (0.15 mm)

Tool: 1/32" flat end mill
Feed rate: 59 in/min (1500 mm/min)
Plunge rate: 15 in/min (381 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.006" (0.15 mm)

Tool: 1/64" flat end mill
Feed rate: 15 in/min (381 mm/min)
Plunge rate: 15 in/min (381 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.006" (0.05 mm)

Tool: 1/100" flat end mill
Feed rate: 8 in/min (203 mm/min)
Plunge rate: 5 in/min (127 mm/min)
Spindle speed: 16,400 RPM
Max pass depth: 0.002" (0.05 mm)