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But it was working well so I continued, without changing the program.
As I often use a router for woodworking I can understand why you would want to move away from that as I would not want to be using it for an extended period of time even when wearing ear protection, the KX3 is not bad and you can easily have a conversation next to it when at 5000rpm. The was a member over on ME forum who won a Shapeoko gantry type machine and he found it very noisy with a Dewalt router and as there was not much speed control had to use small diameter cutters to avoid overspeeding at the cutting edge which just made the noise worse.Like Mike I am limited to a 5000rpm maximum speed which with my usual 6mm dia cutters is OK with steel and cast iron as I can run at the right sort of speeds of 4-5K rpm but I am not fast enough to get the optimum speeds for aluminium of smaller diameter tools.I do try to run at the makers or suplliers suggested spindle speeds where I can but our less powerful and less rigid machines mean the feed rates and to some extent the depths of cut have to be adjusted to the individual machine. I tend to mostly use 0.02mm per tooth (Fz)in steel and cast iron and 0.03-0.04mm/tooth (Fz) in aluminium depending on whether there are any tight internal corners where I will run slower as the cutter engagement is higher and a risk of chatter,So for a carbide 6mm dia 3-flute cutter with a 0.03-0.04 Fz at 5000rpm I would be feeding at 450-600mm/min which is actually not that different to your figures as at 18,000 that would be 1800-2160mm/min. However if it were an HSS cutter I doubt I would want to run it so fast and my 5000rpm would be about the max I would take it to even if I had a faster spindle. Just looking at my YG-1 catalogue for s 3-flute uncoated HSS-bo at 5mm dia they suggest 6300rpm for both slotting and side cutting and the other supplier I use a lot suggests 7000prm which is what made me ask about your chosen speed. Your Fogbuster will help with the speed and is something I still have to sort out though I do now have a better compressor.I can't remember what your mill started life as but that will have the biggest effect on how much you can take off, I would tend to take heavier than you have shown here typically with the usual 3-flute 6mm cutter for the first surfacing I would be 1mm deep and say 5mm wide. Then for adaptive the numbers would be 6mm Ap height x 1mm Ae stepover. I may alter this to suit the job but would tend not to go much over that "area" of metal removal so may also use 12mm Ap and 0.5Ae for example. I tend to leave 0.3mm radial on these cuts and then do a finish contour with one roughing pass of 0.2mm Ae and finish pass of 0.1mm Ae.The bit of your cut that I gave ringed does look a bit "ugly" could it be that the fogbuster is nor reaching the back of the tool?I really need to sit down wit ha big block of 6082 and just try a few more variables out to really see what my machine can do. What I detailed above it is quite happy with and does not sound under any strain plus I can keep up with clearing the swarf and brushing on some lubrication, no doubt it could be pushed harder but as I only use it a few times a month am happy to stick with what I have found works, it would be different if I had a batch to do or was using it several times a week. No doubt you will go though a similar process with the new spindle to find out what works best on your setup. It's all good fun.
I still have a feeling that the Sorotec chart is based on carbide tools not HSS so spindle speed would need to be reduced for HSS.
The fz values (tooth feed in mm/ tooth/ revolution) are coming from this chart.https://webseite.sorotec.de/download/fraesparameter/schnittwerte_en.pdfThe cutting speed Vc ( in m/min) for each material also.It should be easy to prepare an excel spread sheet for easy calculation with the shown formulae.I have done it once temporary, only to see, if it will give similar results as the calculator.