I WOULD recommend buying a bench grinder! A grinder has many other valuable uses, as well. It can be mounted with polishing wheels or cut-off/ sitting discs. Some use it to even the ends of compressionless/ indexing cable housing for cleaner more precise shifting. Grinding the mildly rounded end of an Allen wrench can revitalize it. Shortening bolts and cleaning up the threaded end or thinning down shims/washers are valuable for a myriad of reasons. The imported/ cheap versions cost between $30 and $60. Along with a bench vise, these may be one of the most versatile tools for any home shop. If mounted to a board, they can be clamped to a table or picnic bench when needed and stowed when not.