that are a lot of questions, some of them make no sense since your machine will dictate most of the techniques.

I would recommend going this way :

1. check some Youtube channels:
– this old tony (general, must)
– NY CNC (must)
– Neo7CNC (must)
– Alex CNC (german)
– Sebastian End (german)
– ClickSpring
– and in you case : Innovative CNC, he has good tips and tricks on precision and good finishing.

2. Do some more experiments before ruining your part as above. It seems you have a very dull cutter, worst, at the wrong ‘speeds and feeds’ (the ultimate google search for you).

3. Buy the machinery handbook, your bible about everything.

After all you can definitely archive good results with a small CNC (made of plastic) as seen on the ‘Innovative CNC’ channel. For cutting aluminum on a machine like yours :
1. Buy a 3 flute carbide mill (flat end mill), 6mm works well on small machines, you get can good ones from ‘Sorotec’. Get a few in advance. One can last a month or 12, up to you. They have to be sharp and good, especially on such machine.

2. Take the smallest cuts possible (With/Depth of cut = WOC/DOC) and increase from there. Generally the speed for aluminium is above 6000,  speeds and feeds depend on your machine rigidity and spindel power. However, you should always see good chips in the shape of hairs (or wider), until you experience shatter and vibration, then you just encountered the limits of your machine. You will have to cut slow then and that’s it.

3. Try software : G-Wizard is great for doing some basic calculations, Fusion-360 is not bad either.

4. Last not but least: use at least some oil/lubricant (does magic in your case) !

good luck

ah, something you should check first: if your machine has a play bigger than 0.5 mm per axis then it’s unlikely suited for cutting harder stuff like alloys.

rob4recycle

starter

21/12/2018 at 22:34

I am setting up a precision CNC machine for the purpose of cutting molds from
aluminum. Check out https://openbuilds.com/builds/rock-n-roll.7857/

friedrich

helper

26/12/2018 at 22:28

@cgoflyn
Thank you for the nice overview of Youtubers! Most of them I follow since some years 🙂

In fact the picture seems a bit unsharp in here, the part turned out pretty well (better finish than a previous order from 3Dhubs) in the end, the only problem was, that the injection force was not sufficient in the end to fill the mold.

I really like the cutters of Sorotec too! I like the Pro-Alu Series and the smaller 1/8″ endmills. Sometimes you also find good new/good condition “Industrial Grade” cutters, on second hand plattforms. e.g. Radius Cutters below 1mm or Roughing Endmills

On the performance side I was really suprised how far you can go with such an average machine. Achieved with a 8mm roughing endmill a stepdown of 10mm at Ap=1,5mm at 13k rpm and 1400mm/min.

At this point its mostly about having a more stable setup to push it further, but actually the more limiting factor to me seems the availability of reasonable priced tools in the <1mm Range like a R0,2mm endmill…

What coolant do you use for Aluminium?

@rob4recycle
Is it your first experience about CNC cutting? Looks like an unusual build to me, but I guess you put your thoughts in it 🙂
What are the dimensions of you machine? Looks like a big one, especially on Z!

rob4recycle

starter

03/01/2019 at 19:22

Yes, the Rock-n-Roll mill is unusual because of the specs.  This is my first build but am guided by two engineers who have built high precision machines. This build will handle a 6″ cube of material on the 4th and 5th axis – not built yet.  This is the mold making half of the machine.  The other half will handle plates using the first three axis.  Build upon granite and uses two c-channel rails on each axis for precision.

rob4recycle

starter

03/01/2019 at 19:37

On the performance side …

I will be using a high speed spindle that is used for circuit board manufacture.  These spindles rotate at 160k rpm on air bearings!  I am pricing them from China at about $1500 as opposed to $20k here in the US.  I am also using high voltage, high amp, 6″ long stepper motors to move fast so I can use 1/8″ drills $0.50 and end mills at about $4.00 a piece to save money and make tighter inside corners but it will remove material faster than using expensive larger tooling.

To remove material will do so by drilling holes first then removing remaining material with the end mills.  Less than .001″ will be removed on each rotation of the cutting head reducing the cutting forces to almost zero so tools wont bend and break.

Using the high speed cutting heads will enable the milling of all types of metal, rock, glass, etc. and be very useful in making parts for the V4 equipment.

siemenc

dedicated

03/01/2019 at 19:51

I don’t have my own machine but work a lot with the cnc-machine (shopbot 122x244cm) in our co-workingspace or machines from clients. I mill mainly wood materials (objects/furniture for interiors which I draw out in CAD) but have been cutting some metals and plastics as well for prototypes. For the toolpath creating I use either a diy gcode generator inside rhino/grasshopper or Fusion for 3D milling. I tend to often stick to single-flute milling bits as they are a good all-round option for lots of materials and there’s enough room for material to be cleared. I don’t use any coolant for cutting metals like aluminium, brass or copper.