Ask Mitch - Plane Tuning

When to stop fettling frog fit...

I am fine tuning a Sargent 424 Jointer Plane frog following your videos. It is unclear to me how "dead flat" the pads holding the frog need to be. Have I proceeded enough or would you suggest continuing until the pads are flat right up to the arrows?

BTW - I am using 15µ psa sandpaper.

Garry

Nice to see you tuning an old plane for better performance.
I don't enjoy endless flattening of castings, and I tend to follow an 85 % rule of thumb. In this case that would be, 'so long as there is 85% good contact area, then stop', the remaining 15% will not make a perceivable difference.
From the photo, I would say you were there.
Finish up the tuning and give it a try.

Good luck, Mitch

Recommended watching: Hand Plane Tune Up

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