First attempt at aluminum failed, please help

I read those forum posts, are you suggesting the “fake ball mill” method?

Since this is a 2.5D part (only vertical perimeter walls to cut) you would use the “phantom flat cutter” that is slightly larger than your actual cutter to do the first waterline and pencil set, then the actual cutter size for the final waterline and pencil set.

The “phantom ball cutter” is more involved, but that is for 3D parts.

2.5D machining programs can take an outline you give and simply offset it to derive the toolpaths. A 3D program like MeshCAM is much more complicated. The workpiece doesn’t usually have vertical walls, so the cutter is machining at a point that is tangent between the local STL surface and the spherical ball-end cutter surface. The cutter tip is offset in X, Y, and Z from the point where it is touching the geometry, and if the geometry is concave in the area, MeshCAM needs to check points all around the actual contact point to make sure it isn’t gouging the surrounding geometry. Even if MeshCAM is working with a 2.5D shape such as your bottle opener, it does the same type of calculations.

I’m sure that slicing/printing software has their own challenges so I can’t speak about them. I only know that I’ve thought long about how MeshCAM works, and I really respect the work that Rob has put into it to make it work as well as it does.


Slicers are fairly simple geometrical programs. CAM is MUCH MORE complex.

The CAM you’re seeing here is… primitive to say the least compared to High Speed Machining and more than 3 axes. The software to handle high end CAM is wickedly complex and in a somewhat limited market.

CAM is not just about geometry, it’s about materials, physics, lubrication and cooling, finishes that are accurate/precise to tiny factions of an inch, adapting to power and torque curves and many other things.

Advanced CAM - like High Speed Machining - are beyond what a human can handle - dozens of factors being solved in parallel and constantly adjsuted. Multi-axis - in trivial conditions - is human solvable but serious machining is now way beyond what a human can do (at least in reasonable time).

By-the-by real businesses cannot afford to deal with a product that is buggy or cannot be supported quickly. They are willing to pay to get what they need. Even to the point of $$$… because they get what works for them at a cost they are happy with. In many shops, a $15K (or even $30K) CAD/CAM package makes perfect sense - it saves many minutes of machining time per piece, makes tools last longer and produces finer finishes. They can call and get someone who understand complex machining details and get things fixed quickly.

Shops that have invested decades of learning and training do not simply jump to the latest and greatest neat package. They can easily go out of business if they did. Training and ensuring there are no bugs in their work flows is SERIOUSLY COMPLEX. They stick with what they know and what works for them.

The cost of a package isn’t a simple inducement, even if it is 10X cheaper. They have work to do. The software packages know this and the “lock in” - due to complexity, support, FUD, specialized strategies - slows changes.

I’ve got many thousands of $ invested in CAD and CAM programs, packages I’ve used for years. I’m not about to jump until I THINK I see something that may work at a price significantly less than what I pay per year to keep what I know inside and out running AND I can afford to spend weeks and months trying out my old projects AND am satisfied that the quality is there. PAIN… it’s got to be worth it.

Much of the CNC market is 2.5D and this is well served with many packages (e.g. Carbide Create, Vectric Cut2D/VCarvePro, SheetCAM, CamBam) - at low cost - even for professional shops (e.g. wood working). There is some open source too.

MeshCAM is essentially a 3D CAM program…

The home market and small CNC machines added amazing hardware at accessible prices; the software is largely unchanged. MeshCAM - and the Nomad - are one of the first successful efforts to try and bring the software quality at prices appropriate to the home and small CNC market.

Open source efforts to do CAM have largely been limited to the simple stuff. Limited users and no reason to cooperate. Companies have spent decades perfecting their software and only recently started to deal with the reality of the WEB, small machines, serious numbers of users with limited budgets and so on (e.g. Fusion 360).

IMHO, the 3D printing craze siphoned off a great deal of the talent that was in or heading to CAM and those efforts have taken a back seat. I do hope this all changes, especially as people are discovering that the low end 3D printers are limited, especially in finish quality and durability (things are improving though).

Over time, we’ll see things “loosen up” but it’s not going to happen for a bit. Fusion 360 is SUPERB and a fine example of where things should head. It’s way below what I can use - it lacks 4 and 5 axis machining along with many of the machining strategies I expect - but it’s getting close QUICKLY. I highly recommend that you take a look… I’m pretty sure you’ll be very happy (after you get over the learning curve).


Carbide Motion crashed on me once… I think my vacuum cleaner generated too much EMI on the USB cable. I’m going to order a short dual ferrite double shielded cable soon.

Motors and computers do not get along well. I have my CNC computer on a UPS (that generates true sine waves), the CNC machine on a different circuit so the motor noise goes elsewhere. The UPS provides a high degree of isolation for the computer. I know my grounds and neutrals are correct.

Do use a UPS or a surge suppressor to provide some sort of isolation.

Before going nuts, can you get/buy a cheap ground/neutral checker and check your sockets? Often there are issues that start right at the wall. If the wall isn’t correct, things like computers and CNC machines will go downhill really fast.

Another issue is static. The vacuum, unless it is grounded and has conductive tubing, CAN (you need to check) generate quite a static charge. Enough charge and you zap your CNC machine and computer. I’m willing to bet your tubing isn’t conductive plastic (most of the shop vac don’t use them). The good news is that static issues can be solved via copper wire run though the tubing and to ground.

Like… really guys… put a try-catch around all your hardware IO calls and attempt a resume for me

You really want to risk moving and/or cutting again? That can ruin the piece and even cause a crash. I want the machine to freeze on a disconnect.

I agree with you that the communications should be transactional. The difficulty is knowing where the safe spot is to back up to. I would need to use a USB analyzer to see what’s going over the wire… there may be multiple commands outstanding.

By-the-by, high end CNC machines often have non-volatile memory in them. One transfers the G code file to the machine memory - which is done via an error checked file transfer method - and runs the program from the non-volatile memory.


Hi everyone,

I was just revisiting this thread as I was able to successfully cut 6061 AL with a 1/8" end mill 9000 RPM, 8 feed, 1 plunge with the depth per pass as 0.01 and step over as 0.01. I also used lubricant as well. It was very neat to see!

Now, I was going to try the 1/6" end mill with the same parameters. Being new to CNC, would this set up be ok?


.01" stepover ? what type of cut are you making?

The 1/16th cutters work even better in hard materials with the Nomad, they are quieter during cutting waterline tool paths because they are removing half the material when compared to the 1/8th" cutter.

The Same feed rate will work for the 1/16th, the flutes are easier to clog on smaller cutters though, so keep some air on the tool, or cut in a coolant bath.

Actually, I just made the stepover to be the same as the depth of cut as a test. I was just searching and it looks like the typical stepover is 1/3 to 1/10 of the tool diameter (with 1/16 - it would be 0.01875 - 0.00625).

Does that sound right or am I off in the wrong direction?

It depends on what your doing. And the stepover setting may not apply at all - if for example you are using a Waterline tool path.

Yes, 1/3 to 1/10 is a good range for a finish pass.

When you are waterline cutting a 2D part you are at 100% tool engagement.

A couple screen shots of of the part setup in meshCAM or Carbide Create would help if we are talking about a specific application.

For feeds and speeds comparison…
I cut this on SO3 XL with 7 IPM plunge, 20 IPM feed rate.

It’s 1/4" thick my depth per pass was set at .02" depth.
2 Flute 1/8" bit.

Of course I cheated a bit, using Trochoidal milling. But it came out within the tolerance I needed or my intake valve.

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