Edges rolling back/burring during use

[Sam]

I flat ground my LV bevel edge bench chisels (yellow plastic handled ones) recently at 25 degrees and then put a micro bevel (by turning the knob on the MkII honing guide).
Ever since I've noticed the edges roll back/burr during use, is this an indication that the bevel angle is too low for the work I'm doing ?

Cheers,

Sam

[msiemsen]

New chisels sometimes have less carbon in the edge due to the hardening process, when the chisels are sharpened a few times this goes away. If you overheated the chisels when grinding the edge this will soften the steel and cause the same problem, this too will improve with more sharpenings. Or you have to low of a bevel angle as you suspected and need to change it.

[derekcohen]

Sam, as Mike noted, new chisels (and plane blades) are vulnerable to either rolling over or chipping when first used. The thin bevel steel is either too soft or too hard/brittle as a result of the heat treating process.

The solution is to grind the edge back a little bit, about 1/16", and resharpen.

Another issue is that narrow chisels are at greater risk for this than wider chisels. Not only is there less of a "heat sink" for the narrow chisel, but there is much greater stress on the edge for the same down force.

One further factor is the hardness of the wood. Obviously wood that is too hard is going to stress an edge beyond its ability. The answer here may be to hone at a higher angle (e.g. 30 degrees rather than 25 degrees), or look at your technique (e.g. take smaller "bites").

Regards from Perth

Derek