A three-part series (1, 2, 3) from Mikey over at MachinistBlog.com, a great site for hobby machinists we’ve linked to many times in the past. Mikey has been a machinist for 15 years, and has come ’round to the belief that high-speed steel (HSS) cutters, rather than the pricier, lower-maintenance, carbide-tipped bits, are the way to go on a hobby-sized metalworking lathe. He also makes a compelling argument for using a belt sander, instead of the traditional bench grinder, for making, shaping, and sharpening HSS lathe tools:
A far better option for grinding lathe tools is a simple belt sander, preferably one that uses 2” wide belts. These machines are cheap, widely available and surprisingly capable for home shop use. The smaller machines with 1” wide belts don’t have enough width to grind a tool evenly, the platen is too flexible, the belts wear too quickly, and coarser belts are harder to find. As a tool grinder the belt sander is almost ideal:
- Belt sanders cut very fast and very cool when you use the right belt and a wax stick lubricant. Average grinding time for a 3/8” HSS tool is under 4 minutes and less than 2 minutes for a ¼” HSS tool.
- With their wide flat platens they allow for simple tool alignment so facets are easy to avoid. This is far, far, far better than trying to realign a tool to a narrow round wheel that requires frequent dressing.
- Belts are widely available, cheap, and do not require dressing, balancing, or conditioning. They also have a very good service life if used with wax lube.
- Changing grits takes seconds and going from shaping to a mirror finish by stepping up through the grits takes a few minutes. Honing to a final polish is less than a minute away.
- Belts will snap at the splice occasionally, especially if they are old. This will scare the crap out of you the first time it happens but I find that preferable to an exploding wheel.
Mikey goes on to talk about what belt sander should be used, how common models can be modified and/or upgraded for lathe-tool work, and why the details of tip geometry are important, before stepping us through the manufacture of a general-purpose lathe tool on his belt sander. Great information, with great attention to detail. [Thanks, Mike!]