In order to eliminate planer snipe on the ends of boards being planed you need to understand why it happens in the first place. There are several factors that contribute to this end sniping.
Machine design - When the feed rolls can't hold the board firmly against the table you'll normally get planer snipe. This could be from soft rubber on the feed rolls or a short outfeed bed. Either one or both of these can contribute to snipe or chatter at the ends of your boards.
Dull planer knives - Dull cutter head knives can be a culprit that makes snipe worse. Dull blades will try to push the board away from the bed giving you a rough cut and the end chatter becomes even worse. ( Tersa Knives has an affordable replacement blade system that can help you keep all your blades sharp.)
Not enough feed roll pressure - Feed roll pressure has to overcome the
board trying to pivot at different points as it feeds through the planer.
When the board feeds beyond the feed roll on the infeed side it trys to
pivot somewhere beyond the outfeed roller. This makes the board unstable
while the planer knives are trying to push the board away from the table
at the same time.
1. Make sure the board is supported good on the outfeed side of the planer.
I like to raise the support slightly at the far end, creating a slight
incline. Also, try pushing down on the board as it comes out of the planer. Sometimes this helps stabilize the board as it finishes its pass.
2. If your planer is built with bed rollers start by making sure they're set
to the manufacturers recommendation. After that, experiment a little bit by
dropping them down a little at a time. I've found that this helps sometimes.
3. When sizing boards try taking a skim cut on your last pass. A skim cut
doesn't give the planer knives a chance to dig in and raise the end of the
board after it feeds past the infeed rollers.
4. You can also try feeding boards end to end tight against each other or
sometimes you may be able to run boards side by side if your planer is
wide enough. To try this, the ends of the boards should be offset at least
the length of the distance that your feed rolls are spaced from each other.
This method is good at controlling planer snipe when planing a lot of boards
at the same time.
At one time or another I've tried all of the methods above with mixed
results. There are so many variables involved that something that works
one time may not work the next.
There is one sure fire method that I use to make sure planer snipe doesn't happen. When I absolutely can't lose any length from the board I'm planing I attach side boards to it. I leave these added side boards 4" to 6" longer than the board on both ends. Sometimes, if I need the width, I leave them as part of the project board and sometimes I just trim them off after planing. Either way the planer snipe is eliminated from the project board.