Some of you are purposefully exaggerating my needs. Only a few of you are being resonable. If you absolutely need an example part and the required tolerance in order to understand what I need then fine...I'll give you a sample part...all the way from raw material to how I will measure the precision.
Allow me to point out how and where you have failed to consider what your needs truly are.
Material: 1018 Cold Rolled Steel.
Online Reference:
Metal Express - Error
Tool: 1/4" diameter End Mill with Ball End.
Online Reference:
http://www.shopatcdirect.com/default...rbide+Ball+End
Why are we using a 1/4" dia. tool in a 1.5" deep pocket? Proper engineering choice would be a 12mm tool or even a 12.5mm which will still allow your 1/4" fillets and still have some rigidity.
Starting Blank: 1' long Square Bar Stock with cross-section: 5"x5"
Milling Process: Bore a 1.5" +.01" deep square hole with cross-section of 1.690"x1.690" +/.0005" tolerance for cross-section dimensions (1/4" fillets at all internal edges and corners). Location of hole is 2.5" +/-.005" from one edge of the bar (doesn't matter which side) and 2.0" +.01" from the end.
Now if your pocket was all the way through you could wire EDM the pocket and hold the numbers your asking. But its not and there are fillets between the walls and floor. The length of the straight wall above the fillet is about 1.25". Your Dial Calipers will allow you to measure perhaps the top .5" but most likely there will be a taper in the wall so you will not know the true width just above the fillet.
Starting Blank: 1" Square Bar Stock with cross-section: 1-3/4"x1-3/4"
Milling Process: Remove approx. .059" from two adjacent sides so that the resulting bar has a cross-section of 1.691"x1.691" +/.0005" (1/4" fillets at all external edges and corners)
Note: The resulting finished products will be a square hole with cross-section no smaller than 1.6895"x1.6895" and no larger than 1.6905"x1.6905" and a square bar with cross-section no larger than 1.6905"x1.6905" and no smaller than 1.6915"x1.6915". The design requires that the square bar should fit into the square hole with an interference fit of no less than 0.0000" and no more than .0020". The final assembly will be a 1' long 5"x5" square Steel armature with a 10-1/2" long 1-3/4"x1-3/4" shaft sticking out of it at a 90º +/-.01º angle. The tolerance for the position at the end of the 10-1/2" long shaft needs to be +/-.002" in order to minimize, within reason, the internal stresses.
Initial measurement of the finished products will be made using a dial guage vernial caliper with inside/outside jaws and a precision of +/-.00025". Final measurement of the finished products will be made by heating up the 5"x5" bar stock containing the hole until the bar still at room temperature fits by hand into the hole. The Coeff. of linear expansion will be determined by experimentation using a dial-gage vernial caliper with precision of +/-.00025" and an infrared heat gun with precision of +/-1ºC (expected value will be approx. 15x10-6/ºC). I expect the bar containing the hole will need to be heated to about 155ºC using a propane heater rated at 85,000 BTU/hr. If it needs to be heated more than the expected maximum then the interference will be more than my design allows...and if it doesn't need to be heated at all then it will not be an interference and the shaft will not be centered in the hole and will exhibit movement and deflection with very little force. This isn't rocket science.
Dial gage Vernier Calipers - Are you serious? First off you need a stopwatch and a heat sink to re-stabilize them because the amount of error grows for every second its in your hand. For measuring the block a good tenth reading micrometer would be better suited to the task.
It is crucial that the interference fit be no less than .000" and no more than .002"...hence my initial requirement that the precision of each cut be no more than .001" (+/-.0005" if you wish). I'd also like to point out that using an infrared heat gun with 1ºC of precision provides me with the ability to adjust the dimensions of the 1.690" hole in increments of .000025" (1.690" times 15x10-6)...I'm just trying to get the initial room temperature measurements within a reasonable tolerance. I can modify the measurements of my parts by controlling their temperatures to get them within +/- .0001" if I need to.
The products that I'm going to make don't currently exist, so I can design them anyway they need to be designed. If a product needs the parts to be kept at a constant temperature differential (+/-1ºC) in order to maintain dimensions then that's what I'll have to design...that's my job as an engineer to determine what the parts need to be and how to use them. All I'm asking from machinists here is what CNC machine tools are available for $10,000 that can position a part with +/.0005" precision and have a 2HP spindle motor. If none exist for $10,000 then that's what I will learn and I can increase my budget.