Fiber-based laser and amplifier systems provide highest beam quality in combination with high output power. Specialty fiber types like photonic crystal fibers, chirally-coupled-core fibers, and fibers with custom pump-cladding designs are optimized to achieve further power scaling beyond current limitations. However, such fiber designs can usually not integrated in an all-fiber design and thus do not reach their full potential because fiber-based components such as signal-pump combiners are not availa-ble. We present a precision CO2-laser based ablation process, which is used to machine the cladding of optical fibers in order to enable the manufacturing of efficient side-fused signal-pump combiners. We show the restructuring or entire removal of optical claddings and the structural evaluation by using scanning electron microscope imaging. The machining method allows for a symmetrical cladding modification and forms high quality surfaces which show low scatterin g loss of 0.02 dB. This is con-firmed by inserting up to 97.5 W of optical power into the machined optical fibers and measuring the transmission loss.