At the point in my Acra mill rehab where I will bee wanting to address any burrs or high spots on critical surfaces. My question is are precision stones really necessary, and if so where can I acquire them at a reasonable price. Thanks, Mike
Are they "necessary"? Probably not. They do have a limited scope of usefulness. They will take down VERY minor inconsistancies, but they're not for much that you can feel when running your fingers across. I have to say though, that within that limited scope of usefulness, they're just about magic.
A spectacular additon to these is a carefully made "Dead File", as introduced to me by homebrewed. The same idea kind of, it's a hand file piece with the teeth lapped flat, so just like the stones, they can't dig in to a flat surface, but they're capable of removing larger amounts of metal.
https://www.hobby-machinist.com/threads/precision-ground-flat-stones.101760/post-976980
I think the only way that ground stones will come cheap is if you make them yourself. I was lucky enough to be able to borrow a set the first time I ever needed them, and when the need arises again, I will buy a set and call it an expensive tool, but a good value. But I won't be buying any preemptively, or just in case.
EDIT: I forgot to add- I was fine in my (one) project that I used precision stones for, but I was really close to the edge of a dovetail way. Do consider holding out for a set of stones that has an angled side which is able to fit inside of any dovetails that are part of your project. It's more sides ground, more expensive of course, but if a square stone isn't gonna fit.... You just bought a set of expensive paperweights.