Hi All,
Had my first real go on the Marlow yesterday making up some T-nuts for it (awkward 7/16" width). I got there in the end but I really doubt I was doing it in the most efficient manner. I've done various searches to find the spindle speed (1/2" 4 flute HSS endmill cutting mild steel) and ended up at 800rpm. But I'm unsure about the depth of cut. One place I found said for roughing it should be 1/2 the cutter diameter, so that's 1/4". I was cutting a width of 0.175" off the side of a 20mm sq steel bar but was getting absolutely nowhere with such a large depth of cut. Could well be that because I was hand feeding I was pushing too hard, I couldn't get a feel for it like I can on a lathe. The machine is pretty damn solid but even so I was getting vibrations. In the end I just had to reduce the depth and slog though the metal on multiple passes. The cutter didn't look too happy at the end of it.
I also found out that the coolant drain hole on the table is too small to cope with a decent flow from the pump, bit of a flooding issue there ;)
Regarding feed rates, I've found 0.002-0.008 in./rev for steel giving
6.4-25.6 in./min, presumably the deeper the cut the slower the feed rate? I need to get the feed motor rewired to delta so I can get the power feed up and running!
I suspect I'm just taking these theoretical values too seriously and just need to adjust to suit what the machine will cope with, but for such a solid lump of a thing I was hoping for slightly better results.
Cheers, Rob