The fusion welding of single-mode fibre in the field requires readily portable equipment, and preferably single-man operation, implying that joint monitoring equipment should be contained in the welding machine. The essential preliminary to low-loss splicing is fibre cleaving to within 0.5 degrees of squareness. A hand-held cleaver that achieves this was designed. A fusion-welding machine which includes monitoring of core transmission by local light injection and detection was developed. The machine is microprocessor-controlled, so that fibre alignment and the welding process are automatic. The mean splice loss is 0.054dB. Field experience is also reported.