Hi Howard,
It was a pleasure to meet you at the WIA conference at Valley Forge. It's always difficult diagnosing plane problems from a distance, but thought I'd get the ball rolling.
Using moulding planes on material with grain reversals can present difficulties, but I don't believe this kind of jamming is inevitable. Diagnosing the specific source, or sources, of the jamming, though, can be problematic. Especially since, sometimes, more than one factor may be contributing to the phenomenon.
One potential source of such problems is the tip of the wedge. If the tip has any roughness, or gaps at the bed, breast, or blind-side of the mortise, shavings will find these areas and begin to jam up in the mouth - especially toward the wedge/blind-side. This probably warrants checking, though I suspect it isn't a major source of your problems since your planes work all right in straight-grain material.
Another source may be sharpening, including the match between the profile of the cutting edge and the sole of the plane. A not quite sharp portion of the cutting edge and/or a deviation of the profile necessitating setting for an overly heavy cut, can sometimes lead to such problems, especially with difficult grain.
Another likely source of such problems has to do with the bedding of the iron and/or a problem with the fit of the wedge. If the iron isn't supported uniformly across the bed, especially near the cutting edge (or isn't firmly held down there by the wedge), it can flutter, resulting in the kind of jamming you describe. This can be accentuated by areas of grain reversal. We often see escapements all scarred up and/or mouths overly opened-up in planes where this problem has never been properly diagnosed and corrected. We use blue dry-erase marker on the back of the iron, replace the iron and set the wedge, then remove them and look for the smudge/transfer pattern on the bed of the plane in order to diagnose the bedding of the iron. It may be thought that a too small mouth aperture is the problem, but this is almost never the case in older planes.
Finally, in very difficult materials, a plane with a higher bed angle (say 55º) and setting the iron for lighter cuts (only possible with a close match of the profile of the blade with that of the sole of the plane) may prove helpful.
Don McConnell
Eureka Springs, AR
