Complex sentence: Not all of the drawings are of his own design-he acknowledges that some of them came from works in progress in the workshops of practicing cabinet makers-but he was a superb draughtsman and he set his name on the style of the era.
Split into simpler sentences: Not all of the drawings are of his own design; he acknowledges that some of them came from works in progress in the workshops of practicing cabinet makers. But he was a superb draughtsman and he set his name on the style of the era.