Aluminum advice

So I broke down and finally gave in to my curiosity and ordered some 6061 1/8" stock. There is a metric ton of guidance out there regarding speeds and feeds. So much so that it is hard to know whats right.

If you know of a succinct and relatively definitive source for cutting info please advise. I did see the material Monday on the matter but I am unclear how much one would back off those values for an uncoated carbide bit and not using air blast.

I will either be using a 201, 101, or 102 (whatever is suggested) and likely doing a profile cut.

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The feeds and speeds in Carbide Create are quite conservative and should be reliable:

If you have the option, a coated endmill is highly recommended:

and a single flute is well-worth considering:

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Hi @gsrunion,

There are a few things there. The main constraint when cutting aluminium is chip evacuation, because if chips accumulate and don’t get out of the way fast, they will get re-cut, which soon turns into melting, clogging the flutes, and eventually breaking the tool.

The coating (e.g. ZrN) helps minimize the risks of melting, and then reducing the number of flutes essentially means larger flutes, with lots of space for chips to be evacuated far from the cutting edges. The type of cut also matters, for the same chip evacuation reason: if you mill a deep narrow slot, it will be increasingly difficult for chips to fly away, they will tend to fall/stay at the bottom of the cuts, and get re-cut.

So if you decide to use “a #201 for a profile cut without air blast” for example, you are putting yourself in a difficult situation: slotting is hard, more so in aluminium, and a 3-flute endmill is not the best beginner endmill for aluminium due to its high number of flutes / tight flutes, and no air blast means no “incentive” for the chips to get out of the way.

The only thing you will be able to do in this situation to optimize chip evacuation is using a very low depth per pass, but even then beyond some depth of cut it won’t be enough.

All that said, what you have going for you here is that you will be cutting 1/8" stock, so even when doing a profile cut your will never have a “deep” slot, and you will most likely pull off using a 201 and no air blast, using CC’s values.

The reason why you keep reading/hearing about using ZrN single flute endmills for aluminium is because they are like training wheels: they are almost impossible to clog, so they are just waaaay more tolerant to sub-optimal milling conditions (no coolant / no air blast / deep cuts) and mistakes.

The other universal tip that keeps being mentioned here is making sure your chipload is near 0.001" for aluminium. It’s a magical value, bar none. So if you make sure that [your feedrate] divided by [number of flutes x chosen RPM value] is near 0.001", not lower than 0.0005", and probably not higher than 0.002" to begin with, you are putting yourself in a good position.

Happy metal cutting, and let us know how your first aluminium chips look!

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Thanks for all the input.

Total DUH on me for not even considering that CC would have aluminum feeds and speeds in there. So I am hearing a single flute bit is good. A coated bit is good. That must mean a coated single flute is even better. Guess I will go find one if I find any amount of success with this first attempt at aluminum.

I think I am going to use the 102 (not z for now) and make sure the pause the cut and dust with some canned air pretty frequently. That will be tolerable for this first experiment in aluminum as this will be a small part and not take too long.

Your plan sounds good to me since you are only dealing with 1/8" plate. I can’t recommend single flutes enough for cutting aluminum. That is all I do on my machine. I don’t have air blast, just dust collection. I have a spindle now but I cut a bunch of aluminum with my Carbide 3D makita clone router with good results. I used both coated and uncoated single flutes from Carbide 3D and Amana. If you want to get fancy, Datron makes some very nice tools as well. Their 4 in 1 single flutes are fantastic but quite expensive.

Another thing that will help significantly is a software that will allow you to use more advanced cutting strategies than Carbide Create provides. I use Fusion 360 and love it. Adaptive tool paths and helical or ramp entry really help when cutting aluminum.

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I am still…cough…ramping up on my Fusion CAM skills so I wasn’t ready to add my lack of skill with that to the mix for this first cut. I am starting to use ti more for wood. But I may as this is a simple profile cut.

So no broken bits. I paused and hit it with canned air once a pass, used (probably) way too much WD40, I saw a good amount of bit deflection meaning it probably needed to be further in the collet, and it is a bit rough…but first cut is a success. I will be buying a 1 flute coated bit this evening.

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