Hobby Milling Aluminium

Full disclosure, we have HAAS VF mills, not really very hobby.. hooooowever, we wanted to film some aluminium milling with no coolant, so I guess we learned some lessons about how much harder it is when you don’t have the kit, it felt hobby, don’t judge.

So… this is a warts and all story, plenty of head scratching, and some toying with our presets in MasterCam/Fusion 360.

First problem was we had no 2 flute end mills at the diameter we needed, so I figured if we take multiple passes and a very shallow depth of cut with a 4 flute, taking the RPM down then all would be good, not so much…

First cut saw our stock take on some more mass in the form of half the end mill, this happened twice (I am not the fastest of learners) which killed all of our 5mm end mills we had, not a huge problem as the radius curves were 2mm so we had plenty of 4mm, we had a contour but our stock gave about 2mm perimeter with the tabs with a 6mm end mill, so 6mm was about all we would get away with, so we loaded a 6mm and 4mm, re-calculated the tool paths.. again.. and we were making chips, but then the fun started, and the reason why I hate milling aluminium even in a goldilocks situation, the end mill started to clog with shmoo aluminium, too much heat.

We had been lazily clearing the chips with some compressed air (very lazily) and the occasional squirt of WD, but it did not help, for no other reason than we just did a bad job.

So.. I had to start taking this a bit more serious, albeit this is not a job for a client, no excuses, we hold ourselves to a standard and I was not prepared to let this beat me.

Back to the drawing board, feed and speeds, that had to be a large part of the issue, and it was. We had the spindle set to 12k RPM at first, which was asking for trouble, we dropped it to 8k and then came down 10% decrements until we started chipping, (feeds came down at the same relative decrements) and we got to about 3k RPM (I realise the scale is not logarithmic but we played with it once we got close) and chips were good, we used the compressed air to blow the chips and then a squirt of WD now and then (paraffin would also be good) to keep the end mill lubed and cooler.

So what has this to do with hobby milling, it is elementary my dear hobby miller, these settings should work on any garage/hobby mill, such as the Syil.

Settings we got working are as follows (all in new money):

Spindle: 3000 RPM
Feed: 600 mm/min
Cutting tool: 4 Flute Carbide Flat End mill 6mm/4mm
DOC: 0.2mm per pass

Result was no shmoo clogging the end mill and nice chip, finish was ok. I would never do this for a production part, the milling time increased 500% but if you are making parts for yourself then it is perfectly acceptable given the probability of cutting yourself a successful part.