I bought a router and am practicing. When I cut across the grain (actually, it does not matter, see "conclusion") I noticed that sometimes it tears bits of the wood out. For example, here are two ends of the same piece of 3/4" pine:
Both ends were cut by me but on the bottom you can see the rough cut. This is a hand held 1.5 hp router at ~20000 rpms using a straight blade with 2 flutes. The blade is 3/8" diameter and I removed about 1/8" of uneven material. I used the router base against a clamped piece of wood as a guide. The feed direction was against the blade rotation.
Why is this happening and can I avoid it? Did the router actually rip those bits out or do those pockets already exist in the wood? Is it a problem with my technique, wood quality, or just a normal unavoidable thing?
Following CoAstroGeek's answer I inspected my equipment and tried more consistent cuts to repeat the problem.
I sawed away a portion of the wood near the tear and verified that it was not an internal defect, it looks like I did the damage:
I then cut material off in the same way as above using all four straight bits from the same set, increasing diameter each time. I kept my speed more consistent this time and tried to go a bit faster. Cuts were made right to left in images below. Looking closely, even though I did not have tearing as above, the results are very poor (I burned the first one a lot cutting off too much material, so I couldn't move quickly):
The second bit was OK. The third is the one I was using in the original images. The streaks are in the same positions as the tears. This is probably not coincidence. All four blades also leave light horizontal streaks the whole way down, which I initially attributed to sanding.
Also while I thought my cuts along the grains had no issues, on closer inspection there is still notching:
When I inspected each bit under a magnifying glass, one of the flutes was slightly chipped or dented at the location of every deep scratch. I could not determine the cause of the lighter more frequent scratches.
I tried similar experiments with my other bits, not part of this set and from a different manufacturer, and none had any of these issues.
The general conclusion is this set of bits is probably just crap. It was fairly cheap. It also taught me that I should be very careful when storing bits because even small defects can ruin a cut. I do not know if the dents are manufacturing defects or damage to the bits done by me in storage (all of the bits used were brand new before this post). Time to go shopping.