So you've got a slab or iron. Now what? *LINK*

Re: Connelly book for download

Dan Donaldson

I was surprised. The linux document viewer opened it with no problem.

Re: A clarification

TomD

Obviously machinist regard scraping highly but for what hierarchy of uses. Do they hand scrape the laps used in blanchard mills, or just the bearing seats, etc...

"An old file with a handle (or a cheap imported scraper from MSC or Enco), a cheap surface plate, slab of glass or flat tablesaw top will do for the above applications."

OK, newer files are often surface hardened, and if through hardened dangerous, it also requires a grinder, which if one had and knew how to use... Those enco scrapers are ridiculously cheap though. don't know if they ship to Canada, but that looks like a deal. Don't like the tang construction.

"That the hand work is to make the machine surfaces possible, not something generally regarded as necessary for secondary uses."

Bingo. And by secondary they don't mean ones where they gave up caring, but ones that are lower in the hierarchy of use.

"This might seem so to some machinists, but to those who employ Whitworth's principles and techniques to make gages, machine mating and bearing surfaces, while the eventual goal of such refinement, might well, to those who work at the very highest level, seem secondary."

It's just math, either you need a certain level of accuracy or you don't. Holding a thou which is course for this kind of practice, is very nearly impossible anywhere on the floor. you can get a thou in individual pieces, but getting it over larger pieces is very difficult to measure let alone get. So what utility there is to working above that sphere is pretty self-dillusional. Even granite surface plates are only accurate to that level when of good quality, properly mounted, and maintained with reference to other surfaces. Glass plate, is a joke. The only reason I am pushing the point is that if simple machined surfaces are fine, then there is a whole pile of stuff out there that can be used right away. To start scraping normally one will start with a ground or machined surface, and if that is either enough, or the reference surface, why bother with further refinement.

My experience is one can get a smoothing plane to cut in the tens if one simply flattens it with sandpaper on a jointer, and sharpens the blade with stones that were rubbed against each other.