This question already has an answer here:
Exhibit A, Ryobi 10" surface planer purchased from a yard sale. The blades are wonderfully sharp and the surface of the planed work piece is quite smooth.
No owner's manual, but I was able to find one online.
I've been using this tool to plane down resawn 1x4 and 1x2 poplar, sometimes some 1x6 stock too. I use a resaw fence on my bandsaw and get the stock close to 1/8" thick, then run it through the planer.
Curiously, as part of my research for this question, I discovered that the manual has a lower limit of 1/2" thick stock, yet I've been having good results going to 1/8".
Perhaps this is directly related, but when I put the fresh stock into the machine, I am careful to ensure that it's inserted flat, yet the first inch and a half gets scooped deeper than the desired thickness.
I've considered to use a carrier board if the wood is part of an important project, but when it's not a critical issue, I can compensate for the extra lost material.
I've not had to plane stock that falls within the manual's restrictions. Is it correct to believe that the scooping is caused by the under-thick work stock?