YES, berylium is dangerous to breath!!!! Use a mask when cutting your props, its cheap insurance!! I use a dremal with sanding disks back side only (side with the notch) to get the edge, I get a "hard sloped" dge then feather it out from there try not to take to much meat out and work it to the trailing edge once thats done I hand "wet" sand to get a finer edge and to smooth out the back side also wet sand the cup side of the prop not changing anything here just get it smooth, I dont spend to much time on the hub if there is casting flash on it knock it down with a small fine file, this might differ from some but after its all cut and looks good I go ahead and do a so so polish job to it, clean it then stick it to the balancer. Get a marker so you can mark your heavy side sand a little off the heavy side till when you spin it it stops in a different spot every time then I polish the crap out of it re check your balance when done if its off you can take it back to the polisher and polish the heavy side till its back in balance...