Homemade Tool Post Grinder

Great job. That should work excellently. I have a full sized TPG and a small toolpost mounted pencil air die grinder I use for grinding, and that one you've made should stack up very well against both of those. Router is a good choice because of the bearing/spindle tolerance and collet chuck. I had to laugh at the comments from Practical Machinist Forum - typical. Eg. the spindle overhang is no more than you have for an internal quill on a TPG. You obviously can't run large diameter stones on it (because of imbalance vibration which is likely to occur) but as grinding is done at light pressure you can use small stones and discs to do the job, no problem, just keep your feed speed high. For small grinding stones you will have to contact a company that sells abrasives for the right stuff. They sell small internal grinding stones, and various sized external ones. Cheers Rob