Mike O. wrote:

You can do it yourself but we have ours sharpened.
If I remember, a set of 3 (6 1/8") costs us about $10.00 plus tax to
be sharpened.

Same here. Straight, non-carbide knives are really cheap to have sharpened.

I have three or four sets of planer and jointer blades, rotating a bunch
out to the sharpener when needed.