Hi,
I use 0.5mm Kyocera Tycom endmills also from drillman and get hours use out of each one.
It was not like that in the beginning though, I broke them, lots of them until I learnt how to use them.
Firstly investigate Autoleveller, a software utility that probes the board and modifies the Gcode Z value to follow the wave/bow/warp of the PCB.
I've used it to very good effect for five years.
Note that it doesn't matter whether you use endmills or 60 degree or 20 degree engraving bits, Autoleveller will help hugely. I don't bother
facing the spoil board, Autoleveller will accommodate a few tenths of a mm in PCB warp/bow AND another few tenths of a mm because the spoil
board is not quite flat.
Next....do not clamp the PCB down, the clamps WILL induce bow/warp in the blank. Use double-sided tape to hold the board down.
I use double sided tape and drill two 1.5mm holes and fit two 1.5mm pins to hold the board in place. The pins not only prevent the board
from moving laterally they will, if you chose the hole spacing wisely allow you to flip the board over and have the top and bottom layer line
up. Now all of my boards are doublesided SMT.
Most recently I've started using TSSOP ICs which require 0.2mm between pin pads and so I've been using engraving bits. I've standardized on 0.1mm
tip, 45 degree engraving bits by Kyocera Tycom from drillman. I buy 30 a a time, I usually get ten plus hours from those before the cut quality degrades and I
replace them.
When I started I was making boards with really thick copper layers (12 oz or 420um!!!). Angled engraving bits were no good at all in this thick copper so I used 0.4mm endmills
from drillman. That meant I could use SIOC ICs with 0.6mm between pin pads, smallest trace width was 0.4mm and smallest spacing between traces of 0.4mm. Each side took ten hours,
and to start with I couldn't get more than a 1/4 hr from each. Once I started using Autoleveller and also flood cooling I increased that to five hours! Flood cooling
flushes the chips out of the cutzone and is very VERY important to getting long life out of these tiny and fragile endmills. Note that you have to chose your doublesided
tape carefully and /or use duct tape around the edges of the board to prevent the coolant from getting underneath and allowing the doublesided tape to let go.
I get up to ten hours cutting with one endmill before it gets so blunt that I replace it, so it can be done.
Craig