Blades for a couple of old No4 hand planes?

[deema]

@BarbaraT just a suggestion. Looking at your photos, the chipped blade appears to be a (hope I don’t offend by saying this) rough ground finish. Two things reduce blade edge strength, the first is the undercut created by the hollow ground right at the edge. The second is a ‘rough’ edge creates ‘teeth’ that aren’t very strong. Both if these issues are resolved by a quick few stokes on a stone of your choice to produce a polished secondary bevel edge that’s at say 30 degrees

@worn thumbs has already highlighted that the chip breaker needs a bit of work…..well a lot! The front edge should sit flat on the blade without any gaps to stop shavings getting trapped and fully support the blade.

 

[cowtown_eric]

I'll absolutely agree with the faulty chipbreaker profile!. Easily corrected with a little rubbing on a file!

 

[--Tom--]

Increase your sharpening angle with a microbevel until the edge lasts. If it’s at 27 degrees that’s pretty low.

Also polish the edge and the back. Each groove from rough grit acts as a stress concentrator increasing the likelihood of chips.

Up the angle, up the polish level and you’ll see it start performing.

Don’t do anything with heat