Since we are allowed to cook on Yom Tov, we are also permitted to add fuel to burning fires. Even so, wood or other fuel that is to be used should be prepared for that purpose before Yom Tov begins; otherwise it is considered muktze – set aside for a purpose other than to be burned. What wood is considered prepared for use as fuel on Yom Tov is the topic of discussion of the Mishnayot on today’s daf.
One of the Mishnayot discusses whether wood can be chopped for use as fuel, even if the wood was prepared for burning before Yom Tov began. As we learned on yesterday’s daf, the crucial question here is whether it appears to be a weekday activity; as such, the suggestion of the Mishna is to chop the wood in an out-of-the-ordinary manner. Thus, using a kardom (spade), a megerah (saw), or a magal (sickle) is forbidden, while a kopitz (cleaver – a knife for cutting bones) would be permitted.
It is interesting to note that the act of chopping wood is not, in itself, considered a forbidden act on Yom Tov. Many of the rishonim (Rashi, the Ri”d, and the Rashba, among others) argue that there is nothing intrinsically forbidden in making a large piece of wood into smaller pieces (unless it were turned into sawdust, in which case it would be forbidden because of the prohibition against grinding). According to this position, the reason some types of implements cannot be used is because they are clearly professional tools, and it appears that the person using them is participating in forbidden weekday activities. The Ra’avad explains that chopping the wood would generally be considered a forbidden activity, but it is permitted on Yom Tov as an essential part of food preparation. We limit the types of tools that can be used only because these activities should really be done prior to the onset of the holiday. Since proper preparations had not been done, the Sages insisted that they can only be done on Yom Tov in an unusual fashion.