The Bureau of Mines constructed a microminer--a scaled-down (5- by 5- by 11-foot) continuous-mining machine of the drum type with a unique triaxially controlled head--for use in a research program to study the effects of continuous-mining machine parameters on the generation of respirable dust. This report describes field research with the microminer at the Bureau's experimental mine at Bruceton, Pennsylvania. Experiments were conducted to determine the effects of depth of cut, rotational speed, and sump and shear rates on the generation of respirable dust. The cutting forces were also monitored and compared with depth of cut. There appears to be a reduction in the amount of respirable dust generated when the depth of cut is increased or rotational speed is lowered. Variation of other machine parameters seems to have little effect on dust generation.