Taffy could not help laughing.

His own knowledge of carpentry had been picked up by watching Joel Hugh at work, and just sufficed to tell him that his father was possibly the worst carpenter in the world.
"I think my fingers must be all thumbs," declared Mr.Raymond.
The puckers in his face set Taffy laughing afresh.

They both laughed and fell to work again, the boy explained his notions of the difficult art of mortising.

They were rudimentary, but sound as far as they went, and his father recognised this.

Moreover, when the boy had a tool to handle he did it with a natural deftness, in spite of his ignorance.