On 7/2/2015 10:47 AM, Len wrote:
It appears to be a combination of things. First, the wood does look different from the birch. Much harder and with a slight reddish tinge. Second, I just looked at the cutoff; bowed! Third, I never thought to raise the blade. I was always told to keep the blade low with just the teeth showing. But the idea of raising it to make push easier is an obvious exception.

I finally cut some birch. OK!

Thanks to all for all the tips.

Len

Ideally the gullet bottoms are just above the top of the board. Keeping
the blade low is mostly for safety reasons.