Visualizing Tolerances, and Geometry Question

Thanks Cube. But I still would like to know all the in and outs of the questions I had, but you do indeed have some useful input.

I understand the tool tolerance well. I am learning for precision wax cnc milling, 4-5 axis. As well as precision casting(which has some quite intense tolerance equations).

So right away for the objects to be casted, in regards to tolerance there’s shrinkage rates of metals, mold materials, keeping details, how much of a detail is possible with vaccumed investment, perfect heating of investment mold, perfect amount of time taken to burnout, temperatures of burnout, sprue placement, on, and on…

Then there’s plenty of work to be done after the casting, fitting parts, laser welding, soldering jigs/fixtures, proper amounts of solder/heat, filing, buffing, polishing.

I also work with glass, and am expanding my tooling, capabilities, to work all forms of glass. From flameworking, fusing, casting, faceting, drilling, sawing, etching, dichro etching, dichro extract embedding, to sandblasting.

Glass is a whole nother ball game, where you start off with huge tolerances, try to battle gravity, inertia, laws of heat, chemicals that color glass(metals and metal oxides for the most part), flame atmospheres. To get technical on the glass cutting, it would come down to the drill you are using, runout of the bit, the silicon carbide/diamond/synthetic diamond grit, sizes of grit, whether the grit sizes have been filtered via water separation to below a certain tolerance of particle size, how often you cleaned out the pores of the diamond coated bit so that powdered glass doesn’t build up, whether boart/grit used in addition to bit gets between the bit and glass, and widens the hole larger than the bit…and on and on!

In flameworking, if you can produce unique stuff, anywhere near anything symmetrical your pretty good! Even with precision cutting of glass down to a 1/000 of an inch, as Cube stated = or - 2mm would be pretty good. So flameworking certain things such as labware beakers, graduated cylinders, etc…take intense robotics/quality control/etching and is not done by humans. Although these kinds of things are possible, and giant 2 feet diameter cylindrical-like freeform light bulbs are done by humans using massive lathes and about 12 torches in a crossfire. They set their lathe and torches and then duck down for a minute or two with heavy flame and heat retarding protection equiptment, stand back up make an adjustment, duck down!!! Compared to a standard flameworker, these setups are intense. Although I have a small crossfire of my own.

But symmetrical in glass isn’t easy at first. Keeping symmetry is glass takes a lot more skill, than keeping a cnc’d piece of metal symmetrical! You can use squares! Everything in glass is circular, and just like drilling a square hole is in metal, flameworking something symmetrical and square enough to trick the eye is the key. Same goes for engraving metal. You mess up, say on a square outlined setting, you expand it out further as well as all the other ones one the piece so that it looks as symmetrical as possible.

You know, sometimes it is fun to really look at and piece together the absolutely massive physics equations in simple tasks.

So each step involves tolerances, and those I understand mostly. So, everything down to how rhino processes commands is on my list.

With that stuff being said, I’m not understanding your 1000mm line example and I appreciate you taking your time to try helping me.

The recent video on tolerances stated osnaps being exact operations.

So does butting the line up to the line perpendicular produce a exact butt, or not exact butt, but within tolerance so rhino says its exact enough to produce a exact model with the data?

Here’s a much better question: When a surface can be merged, lines are connected, polysurface’s edges edges all meet and close a polysurface into solid. After the connections, does rhino change or overwrite the geometry to appear exact, or define the shape as closed, or do it’s previous approximations before a join remain? Is it overwritten as a perfect shape, or exact once operations have been performed, with a history embedded to previous deviations but does not matter since the new code is perfect?

I’m just trying to understand if it actually keeps track of how far away exactly it is, and within tolerance, or if any spot within that tolerance (variable) is what is written in rhino’s geometry. Bascially, does it come to a random location known to rhino to be this close on any axes of the objective, or does it pick a spot down to 1/1000 of an unit away from the known object?

Thanks a lot for any help on my quest.