The 2 main blades on the drum are not adjustable as they can only be fixed in one position. The only thing one can do with the main blades on the drum is flip them around to use the other side of the blade or replace them. That would just involve removing and putting back on the bolts. Just be careful to not drop the blade or bolts into the drum. � The only other blade that is adjustable is the bar blade/anvil located at the base of the drum. You can see the bar blade when the front chute is open. It is held on by 5 bolts. This blade is already set by the factory but it can be adjusted if needed. Loosen all 5 bolts (do not completely take them off) and then the bar blade can be slid up or down a bit if needed. � Make sure the whole area is cleaned out and there is no debris inside and once it is set to the desired depth tighten the bolts down. Having a straight edge like a ruler between the blade and bar blade will help keep it in place as it is being tightened down. This would only need to be adjusted over an extended period of time when the bar blade starts to wear down.