Many times we have had questions regarding routers, end mills, drill bits to create pcbs or to mill particular materials. The world of the "end mills" it is a real universe.
Frankly speaking on the market there are thousand of mills, good or not, expensive or not, and not always to get a good job it is necessary to purchase expensive items. In the picture, for instance, you can see a self-made mill to create a prited circuit board simply using the head of a small broken end mill, rounded with a drill, cutting the head with a simple router .. and it worked quite well.
In many other cases we purchase normal, often cheap, end mills (see right picture) to be used for milling, drilling and cutting pcbs. In the picture the drill bit is a 0.6 mm (for drilling) the `big` end mill (0.8 mm) it is normally used to cut the pcb border or to make big holes in the pcb, the single flute end mill is used to create the tracks, pads, vias, ... on the pcb.
All of them are probably the cheapest mills on the market bought in many online shops abroad.
Milling a pcb is nowaday probably the quickest solution without the use of acids, lamps, photoresists etc. Usually the result is really good but, before components soldering, a quick tester check of the surface is warmly suggested.
On the market is quite easy to purchase 'bulins', or 'vgrove' mills. Such a kind of mills are really interesting to realize pcb. It is important to find an area oin the cnc machine characterized by a good coplanarity because even a difference of only 0.1mm of coplanarity could represent a problem for the final result.
Such a mills are really cheap but they have a short life and must be changed (or resharped) quite often. Such a mills are really interesting because they can be purchased to realize very small groves (even 0.1mm) for the tracks.
Unfortunately very small double flute end mills (0.2-0.3 mm.) are too expensive (60-150 euro) therefore are not used in an hobbystic environment. The breakage of an end mill can be considered normal during a routing process therefore, in our humble opinion, it is better the purchase of 50, short lasting, end mills than only one high quality end mill (the numbers have a real proportion).
Router bits, in the picture, are absolutely perfect to cut even in only one pass pcb boards and light material (light wood, balsa, carbon or glass plates etc.).
The solution to this problem consists in the use use of the right end-mill. A single flute end-mill will give to the burr enough time to escape from its site, preventing the kneading of the material around the cutting head of the end mill.
