Any timbers to avoid?

[EddyCurrent]

Another couple of newbie questions I am faraid

Are there any timbers that should be avoided in regards to routing ease and finish?

Also, is it possible to simulate fretwork with a CNC router? if so what sort of tooling and would it need to be roughr out with a large diameter tool first?

Thanks in advance

Oak can be a problem with long splinters coming off, especially if you route against the grain. It's similar for any coarse grained wood or where the grain changes direction, tearout is always a danger.

With fretwork it implies cutting right through the work, so I use the smallest end mills I can easily find such as 1mm diameter. e.g. http://www.ebay.co.uk/itm/10pcs-1-1m...item3f4026bae9
It leaves a 0.5 mm radius in corners that can be left or cleaned up with a suitable hand tool such as a knife. You can take a roughing cut first with a larger cutter, leaving a 'roughing clearance' of about 0.5mm, then take a finishing pass with the small cutter preferably full depth.