I wanted to cut a 2" deep pocket into a piece of stock which is 2.5" thick.
I selected a #201 endmill. When I chuck it all the way into the router, I only have about an inch and a half of depth before the collet will hit the work piece. I know it’s not a good idea to chuck it further out of the collet. So effectively, my maximum cut depth is only about 1.5".
I looked on the Carbide 3D website for bits with a longer shank, but even if I could find one (which I can’t), I am sure I will run into the upper Z limit on the router.
I had purchased this 3" bit for a deeper project I had. Yes you do need to be mindful of the longer bit and machine movement, also I had to mount the router higher up in the clamp for a task.
Using a #201 will never cut that deep of a pocket. I think it is rated for 3/4" deep. The problem is when going over that depth the shaft of the bit is rubbing on the sides of the pocket.
Seating any bit in the router collet should be pushed in so the top of the router bit is at least at the top of the collet. You would have to measure your collet length but it likely around 3/4" of an inch. That gives you the best grip on the bit in the collet. You can push the bit up farther but never to the top of the router shaft. The top of the router shaft is not even and when you tighten up the collet nut you are forcing the collet and bit up an inclined plane to squeeze the bit and collet tighter and tighter. So if the bit is all the way up it has no where to go. So the bit can come loose because it is not properly tightened. So only push your bit up to the top of the collet to get maximum cutting depth.
I have a Melin 4" OAL bit that I cut 1.5" deep pockets. So I have to move that bit up further up into the collet to avoid excessive run out. Plus with longer bits you get more vibration and the collet can come loose from that vibration. So pause often and check the tightness of long bits during the running of longer jogs.
Cadance Manufacturing has a line of Jenny bits and they have one that can cut up to 2". They reduce the diameter of the bit shaft above the flutes of the bit so you can cut deeper. The #201 would rub on the side of the pocket and could cause burning. So get yourself a longer bit to do deeper pockets.
I will vouch for the Cadence MFG Extended Reach bit. When using it I really back down the speeds and feeds as well as the Doc. You will have a lot of tool sticking out and I feel it can cause issues running too aggressive.