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Aluminum and Brass are the two most commonly machined alloys. You can CNC brass and aluminum in your home workshop with a suitable CNC machine and bit.
Due to the hardness and durability of brass sheets, it is excellent for a wide variety of uses from decorative to jewelry.
Brass serves as an excellent accent piece for woodworking projects, and Etsy sellers often mill small brass accent pieces for their projects using a CNC router.
Brass also engraves well with a CNC router. Your logo or floral design can be etched permanently into the metal. CNC machining of brass is an excellent way to offer custom brass engraving. The freshly machined surfaces offer that bright shine that makes brass so attractive for engraving.
CNC milling is a $740 million industry. This article will help you get your own little piece of that pie.
Tips For a CNC Machined Brass
Engraving brass or cutting thin sheets of brass are easily done on an at-home CNC router. If you are looking to do something more complicated — such as milling brass fittings for your air compressor hoses — you’ll need a larger, more professional-grade machine.
You can easily mill copper and brass sheets up to 1/16-inch at home with a CNC router such as a Shapekeo.
#1. Choose an alloy that is easy to machine using a CNC router.
Aluminum 6061-T6 continues to be the top choice for at-home routers. It is also available in different heat treatments, making it a more versatile metal. For added hardness, Brass 36000 is a popular choice for hardware, bolts, and valve seats.
#2. Select a bit that works for brass and aluminum.
You need a bit that isn’t going to deflect, or bind to the brass. It needs to clear chips well, and hopefully offer a long bit life (it’s a pain to stop mid-way because of a broken bit. I almost always ruin some raw material when this happens).
A 3 flute end mill bit with an aggressive 45-degree angle cut should work well. For cutting brass, you will likely want a narrower bit such as a 1/16th inch bit.
#3. Secure your material well.
Since you will be working with thin material, you will want to secure your material well to prevent shearing during the cutting process. Basic scotch tape can work, but Elmer’s glue works surprisingly well and cleans off easily after. Wax is also a great choice since it releases the material when a little heat is applied.
#4. Check the RPM and Feed Rate Calculations ahead of time.
A 6-inch per minute feed rate combined with a .006″ depth of cut and 19,500 RPMs is a pretty good place to start. You may need to tweak this some for your machine, and how intricate of a piece you are engraving. If you are trying to cut all the way through, you may need a slower feed rate or multiple passes. Going too aggressive will shorten your tool life and damage the material.
#5. Start With a Lighter Depth Of Cut
Most CNC operators make an “educated guess” when it comes to depth. With a CNC router, you will need to use a light depth and make multiple passes. Something like a G-Wizard Calculator can help you pick the correct depth in a more scientific fashion. When choosing an optimum depth value for brass, choose the one closer to .05’’ whereas.03’’ for aluminum.
#6. Always lubricate the bit for better results.
Even when cutting “soft” aluminum, the heat creates a small “heat-weld” event at the endmill. You need a little lube to keep your bit from sticking and breaking. Even a little WD-40 can make all of the difference. I like to use lightweight gun oil, but any lightweight oil will work for this.
Lubrication also helps combat heat from the CNC process. Sometimes a thin layer of lubrication can be wiped across the entire metal prior to engraving, and that will work well. When doing deeper cuts, it may be necessary to keep a long-nosed oiler handy for apply spot lubrication to sticking points.
#7. Clear the chips when done.
You can use compressed air to help blow the chips clear of your bit as you work. Always use eye protection when working near your tool as flying shards of metal are harmful.
CNC machines create a lot of mess wherever as they work. These tiny chips and bits of pieces are not easy to handle.
You may also notice that the chips may interfere with cutting during the milling process and create more heat. they can also damage your working surface.
With woodworking, a vacuum nozzle works fine. I find when machining metal, it is cheaper to blow the metal shavings away. Metal chips are much heavier than wood shavings.
At the end of the day, a good sweeping job around the machine does a good job collecting the metal shavings.
These chips or “swarf” are often recyclable.
The Types Of Alloys
Aluminum is highly valued for its lighter weight and softer material. Brass offers more hardness for daily touch and vibration wear. Both have high corrosion resistance and are inexpensive. Here, we look at each of the alloys in more detail.
Characteristics Of Brass
Like other copper-zinc alloys, brass behaves well during milling and in creating low tool wear making brass a popular choice. Brass is relatively inexpensive and holds up well over time in real-world uses, making old brass items highly collectible. Additionally, it is malleable and non-ferrous; hence we can recycle it easily.
Cutting brass reveals an excellent surface finish. With a little clear coating, it shines well in daylight. When hardness is not the top priority, choosing a brass with high lead content can increase its machinability. 360 Brass is often called free-machining brass, thanks to its high lead content.
Characteristics Of Aluminum
Aluminum is a popular copper alloy. Aluminum is much softer than brass, and thus it is easier to mill. Like brass, it is also non-magnetic due to the copper ingredients. However, if you use cutters for slicing, it may stick to its surface. Hence, when cutting aluminum, you must ensure proper lubrication.
Wrapping It Up
Milling metals is a fun challenge. CNC machines let you mill alloys with greater ease. When picking an alloy for your task, consider the strength and durability of each one. Although milling a metal alloy is more expensive than woodworking, CNC machining has made it much easier.
Hopefully, this guide gives you a starting point for milling alloys like brass. The process is quite affordable, from choosing the right material to selecting its good bit. Maybe it is time to add brasswork to your Etsy store.