Does anyone have drawings/Models for the various VEX/Andymark etc that have tolerance values?
I appreciate that they have CAD models/Drawings, but just a current for instance:
The hub on the Versahub (any of them) is spec’d at 1.126", and I’m about to machine some parts to fit on them. So, just to take it to the extreme, if I machine it to 1.1265, in theory (hahaha) it’ll fit, but we all know there are tolerances.
So, what are the numbers? I mean, I’ll just make mine 1.131 -0 + .003, and assume it’ll fit (I can’t try every hub out there), but who knows, and I’d LIKE to make the part tighter
if you’re trying for a ‘fit’, I think you’ll need to define that more. A press fit? A locational clearance fit? a running clearance fit?
If you need a press-fit, I think you’d be better to buy some of their parts and measure them. Likely the standard deviation is small even if the actual dimension is not accurate, ie. near their tolerance limits (low or high).
I don’t know how much you know about fits, but it’s all available on the internet…A press fit usually you want to see much tighter–like 0.0005 or 0.0010 of clearance (which varies with your diameter–this would be for under an inch), with a +/-0.0005 tolerance on your diameter.
Oh, I know all about fits (I don’t need the internet, I have the Machinery’s Handbook)
What I DO know is you do need the tolerance of the mating part
Say (roughly) the mating part is a Nominal size of X. If it is +.005, your part needs to be different
In this case, it is a simple locational fit - aka I just don’t want it sloppy.
I did net an answer from Vex BTW - that hub is nominal 1.126, with a tolerance of +0/-.006, so if I make MY part -0/+.003, I KNOW my part will fit, and will never go over .009 clear, but will never be an interference fit
All of the AM drawings I’ve seen have specified the tolerance in the legend, as a function of the number of decimal places. From the AM-2952:
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN INCHES
TOLERANCES:
FRACTIONAL+/-
ANGULAR: MACH+/- BEND +/- 5 deg
TWO PLACE DECIMAL: +/-0.010
THREE PLACE DECIMAL: +/-0.005