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With the appropriate strategies and tooling your CNC router can mill brass and aluminum with dependability, accuracy and consistency. Milling these supplies on a house store CNC router isn’t troublesome, however milling steel requires a completely different and a disciplined strategy. Here is a primary components to get you began:
1. Stick with simply machinable alloys.
2. Choose the bit that’s right for brass or aluminum.
3. Mill at an RPM and feed fee that’s proper on your machine.
4. Use a gentle depth of reduce.
5. Lubricate the bit.
6. Clear the chips.
We wish to select an alloy that machines simply, is usually accessible and is reasonably priced. Aluminum alloy 6061 is a nice option to work with. Manganese and silicon are the most important alloying parts. Alloy 6061 is powerful, corrosion resistant, cheap and extensively accessible and will be simply machined on a CNC router.
Ultra-machinable 360 brass consists of copper and zinc, and as you would possibly guess from the identify, it’s made to be simply machined with the addition of lead. This enticing alloy stands as much as excessive velocity milling with minimal put on on tooling whereas producing chips that clear simply from the reduce.
The Right Bit
The bit we’re in search of doesn’t deflect, minimizes lateral forces in your router and clears the chips rapidly to offer you a high quality reduce and lengthy bit life. The bit that accomplishes this for each aluminum and brass is a 1/8“ diameter, 1/4“ shank spiral upcut and with a size of reduce that’s about 1/8“ greater than your max. depth of reduce, however not far more. The small diameter reduces lateral pressure in your machine which will increase accuracy. The 1/4“ shank and brief size of reduce reduces chatter and deflection whereas the spiral form clears waste chips effectively, however what number of flutes? This is the place brass and aluminum half methods.
Aluminum is a “gummy” steel that may cling to the slicing fringe of a bit. Once that happens, breakage is barely moments away. What’s wanted is a single-flute, extremely polished bit that each clears chips rapidly and prevents them from sticking.
360 brass is alloyed particularly to chop cleanly so a two-flute bit can be utilized. Two flutes supply the benefit of extra stability and extra slicing effectivity.
RPM and Feed Rate
Speed and feed fee calculations offer you a perfect set of numbers to chop steel. However, house store machines undergo from a lack of rigidity. To compensate, we have to decelerate the feed. I’ve discovered that a feed fee of 50 fpm at a velocity of 19,500 rpm is a mixture that can work properly in most conditions. Don’t go beneath this making an attempt to child the machine. Feed charges slower than 50 fpm trigger the bit to rub needlessly growing warmth, put on and decreasing its’ life.
Depth of Cut
Bit deflection, backlash, and body rigidity are enemies of a clear reduce. To counter these, we have to select an optimum depth of reduce. For aluminum 6061 I’ve discovered .03“ to work properly and for 360 brass .05“. It may not seem to be a lot, however you will see your CNC router can clear a lot of steel in an hour’s time.
No doubt you may have had the expertise of scorching some wooden whereas routing. The dense construction of steel creates much more warmth because the bit balances between slicing and rubbing, so lubrication is essential to conserving the bit cool. A cool bit means a longer bit life and a higher reduce. To lubricate a reduce there are a number of choices: wax, spray can oil, or an oil mister.
If you’re slicing skinny sheet inventory in a single move, a wax stick is smart. Wax sticks are much less messy than oils and have the benefit of being utilized as soon as and letting you stroll away. No babysitting.
For cuts requiring a number of passes, the best strategy is to make use of oil from a spray can at frequent and even intervals. Avoid utilizing sprays which are designed for stopping squeaks and breaking frozen bolts. Choose a devoted machining oil or an oil with some cling (akin to chain lube).
The greatest strategy that ensures fixed lubrication for the bit and no babysitting of the machine is to make use of an oil mister. It’s an add on and makes use of compressed air to suction oil from a reservoir and delivers it on to the place it’s wanted: the router bit. There are many specifically formulated oils for machining, however in our state of affairs the oil just isn’t recoverable. Once it’s sprayed it’s gone, so value issues. An cheap slicing oil that may be purchased in gallon jugs goes by the identify “Plumbers Lard” (not a glamorous identify nevertheless it works). I additionally preserve a spray bottle of this oil in my store for steel drilling or CNC work once I don’t wish to use the mister.
Clear the Chips
You know that milling wooden produces a blizzard of chips. Milling steel can do the identical. Chip buildup ends in re-cutting the chips, growing warmth and stress. It’s the primary reason behind damaged bits when milling steel.
So how can we deal with the chips? They will be blown out of the reduce with an air wand or, when you have a bigger compressor, arrange a steady air stream utilizing a versatile nozzle hooked up to your router. (Take care to be very cautious when utilizing compressed air on steel chips, because the chips can find yourself in electronics, in-progress wooden initiatives, or worse, in your eye.) A mud collector will help preserve the workpiece clear, however steel chips are heavier than wooden. You might have to suit a customized boot to extend air circulation across the reduce.
Cutting aluminum and brass with a house store CNC router is an thrilling course of. By addressing the problems distinctive to milling aluminum and brass, you possibly can mill with confidence. So, decide up some slicing oil and the appropriate bits, and open the door to a new world of potentialities on your store.
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