Originally Posted by
dharmic
I tried a bunch of things with normal jobber bits on my X6 and pretty much gave up on drilling ali with this thing once I got bigger than about a 5-6mm hole. Too high RPM and you burn bits - even worse if you reduce the plunge feedrate because the tool then just rubs. Too slow (I'm really hesitant to run lower than about 8000RPM because of this) and you can hear the spindle bog down, down, down and stall.
In the end, for wider stuff (7mm+) I'll do a helical bore using a 6mm two flute and that seems to work really nicely.
For the really little stuff where I can keep the RPM up, it drills just fine.
For the in-betweenies (3-8mm?) it depends on how many holes I need to do. If it's only a couple I just spot drill the hole centres to a couple mm and then, when the routing's done, I manually drill the buggers on the drill press. If it's repetitive work it's worth either helical boring with a smaller two flute or tweaking and tuning feeds and speeds with a decent bit to get it done on the router.
If you're like me and using this mostly for aluminium, do yourself a favour: stop being such a tightarse on tooling. I switched to carbide a while ago, just cheap Chinese bits from danyazhan0 (Klot tool store) on eBay, but they deliver quick and the tooling is a dream to use. For a lot of stuff it's cheaper than HSS bits because although it costs $5 instead of $1 for a 6mm cutter, it lets you run a heap more aggressively (saving time) and lasts a million times longer. Of course, the $50+ 6mm cutters from Sandvik et al are another world again but hey, if we're only using an Omio then let's face it - we aren't expecting that crazy level of accuracy anyway.
HSS still has its place - I use HSS bits for cutting MDF forms and foam, and it was nice and cheap when I was getting started and regularly plowing the tooling into the side of the job, the fixtures, the bed, the wall of the shed etc by being an idiot with the CAM, MDI or even just jogging. But I like to think I'm past that now (mostly, anyway) and even the cheapo carbide stuff makes running ali on these machines quicker, quieter, less cringing-at-the-howls-of-pain-from-the-machine and overall a much happier experience.
I also installed a $20 from ebay dual nozzle mister setup which I run from a gravity fed bottle of 20% methylated spirits, 80% water mix and it's worth a go if you have compressed air. Getting a stream of air to the cutter blowing chips out to prevent re-cutting makes a big difference to tool life and finish on the cuts, adding that mix of alcohol and water (pretty much what the Datron machines use IIRC) keeps things cool and lubricated without the residue of WD40.