My only experience with big box planes was with Lowes Kobalt No. 4. I worked for 3 hours with sand paper attempting to flatten the bottom, and still had a ton of high spots, would have probably taken another 2 hours. Also the major problem with the chip breaker would not seat against the iron, there was always a gap no matter how much I sanded and filed. So every time I used it, wood would jam between the chipbreaker and the iron. Needless to say, I took it back got my money back and then found an old Stanley No. 4 in a barn for $10 and spent 1 hour restoring and it runs like new. I’ll never buy new planes again!