While my first effort seemed to go OK - it was probably beginners luck - as I have had problems since in making multiple copies of the Harvest mouse keyring.
I'm not making it easy by trying to engrave stainless steel - which I now know is probably the hardest surface to engrave. And while production metal suppliers will tell you which type of Stainless Steel you are getting, many suppliers of these type of trinket items probably don't even know that there are different stainless steels. Anyway it seems I would be best if I used 416 stainless steel, then 430F, 303, 420F, 430, 304 and finally probably avoid 420.
On the tool front - I began using 30 deg x 0.1mm single flute carbide cutters that I sourced from ebay. Why? Because I knew no better and they were cheap. It seems I should be using 45deg x 0.1mm quarter-round micro-grain carbide cutters as these are less likely to fracture at the tip - which is something that was happening often as soon as the narrow angle cutter touched the stainless steel surface. I'm awaiting some of these micro-grain carbide cutters - but they are not cheap.
I was also running too fast a feed rate (400mm/min) and plunge rate (100mm/min). Again didn't know any better at the time - have now reduced that to 250 (feed) and 40mm/min (plunge) - seems to work better. And while I should be machining at something like 20-30,000 RPM or higher, my CNC machine has a maximum rpm of 15,000 (as shown by my excellent laser rpm meter - I recommend these to anyone who wants to calibrate their lathe, mill or cnc machine (less than £10 from Amazon - search digital laser photo tachometer)
I've also taken to covering the disc with a layer of 3-in-1 oil as a lubricant/coolant - I'm using Newplast modelling clay to act as a "bund" around the disc to keep the oil inside.
If any one has any comments to improve my current machining protocol - I'm as always - all ears
