I found the same problem initially with my KX1 where I wanted to use small diameter mills and the recommended spindle speeds were much higher than the KX1's 7000rpm. But I found a feed and speed calculator which allowed for wide spindle speed ranges and I used it to calculated feeds and speeds for the typical mills I would be using – 0.5mm – 2mm carbide slotting cutters. I can't now remember which piece of software it was since it was quite expensive and I used it on its 30 day trial period.  But I've just found another calculator online which allows the the maximum spindle speed as a parameter and that might be worth a try.

**LINK**

I still had to do a bit of experimentation and it got a bit expensive for a while with the ends of small carbide bits pinging off during cuts. But I've now got a set of feeds and speeds which give me a reasonable life from the cutters.

Jim.

Edited By Jim Guthrie on 03/07/2019 09:08:54

All these feed and speed calculators are meant for industry where cycle times are important, they are way out for model engineers.

I think it is the feed rates that can seem a bit fast at first. If in doubt think about how fast you would be turning the handle on your manual mill for the same sort of cut and what speed you would be using using.

For example if you were running the manual machine at 2000rpm and winding the handle (10tpi) at one turn per second then you would be feeding at approx 150mm /min. So if the cutting speed for that cutter is now 6000rpm which is with your higher top speed then you also need to increase the feed 3 fold to keep a similar loading (6000/2000). If in doubt set it a bit low while you get the feel of things as it is safer to override the speed upwards as it starts to cut if you feel it could have been more than to start cutting and get a lot of vibration or a bogged down cutter and then desperately rush to slow the feed. You can also react faster if things go wrong.

As Andrew says if you know where the cutters are from the makers give feeds and speeds for different types of cut, cutters and different materials so you can get an idea of where to start and then make a note of what works for next time. The hardest one I found was working out how fast you tend to feed a drill down into a hole.

I did some practice cuts in plastic first just to get the feel of things before moving onto practice cuts in metal and then finally parts I actually wanted. You will soon start looking at the statistics on the F360 simulator to see how long a part will take to cut and then seeing where you can get the time down.

I've not had much chance or need to play with my KX3 recently but should have something a bit more challenging for it to do in the next few days when the metal arrives, will post in my thread.

When working with the KX1 toiday, I just remembered another thing from my experiences at the start. I suspected that my spindle speeds were not as requested by the GCode. So I got a cheap tachometer which I checked against my Cowells and found it pretty accurate. I then checked the KX1 spindle speed and it was running much slower than reported by the Mach software. It wasn't too difficult to adjust to get the correct speed and the life of my small cutters improved no end.

Jim.