I've just sent a PM.................... with a heads-up.
But, Andy's right, a good knife or cutter gauge is best across the grain. Personally I've never had decent results going cross-wise with these spurs, and they can be a tiny fiddle to sharpen up........
Clean-sided trench walls going with the grain depends a lot a sharp blade with clean, sharp corners, even then I may use a side rebate plane to clean up.
All best.