Depends on which dimensions are important and which aren't.
Say you had +-.005 on all the dimensions in your examples.
it could be:
<----1.005--->|<--------2.005------>|
for a total of 3.010 max dimension.
while for the other method
3.005 would be the max dimension.
but this could happen...
Also,
I've been looking more at screws and thread specs for 4-40UNC-2a/2b in machinerys handbook trying to get some insight on this.
Max pitch diamater of screw 2a=.095
Min pitch diameter of internal 2b=.0958
Min clearance--------->.0008 (this is what i designed for)
Min pitch...
Interesting.
Maybe I should mention these parts are made out of aluminium so it is very possible that the steel screws chew through the material and accommodate other errors in manufacturing.
And this might not even be a huge problem, these parts aren't loaded in any sense.
Kenat,
My confidence on being able to get the .002 tolerance goes back and forth. At my shop we very commonly tap #2 screws (0.086 max size, not nominal) and always drill 0.089 clearance holes for them. I've never had screws not successfully mate with these parameters.
I was very surprised...
Kenat, Your spreadsheet and examples have been extremely helpful.
Yes I agree after learning a lot about GD&T and personally struggling with spec'ing these shoulder bolts I would much rather prefer to have alignment dowels and then just clearance screws to tie the pieces together on the side...
Thanks powerhound.
1) oops yeah i haven't double checked everything like that yet. Definitely going to fix them up before i finalize this drawing.
2) Indeed. I've been wondering how to do it actually. I'm not interested in the holes position relative to any side walls. So is it okay to just...
Thanks for reply kenat.
I have the 1982 y14.5 in my possession and 2 books on GD&T. I've read the section on positioning extensively. And i've downloaded your spreadsheet on fixed fasteners.
All that matters in this part is that one lens, the one in the 45degree plane, gets placed well relative...
Hey all.
I've been put to the task of drafting up drawings of a ~15 part precision optic system. Fortunately I've personally already made all the parts on the CNC, and I know that a large scale production shop shouldn't have a problem producing the pieces.
Many of the pieces are...
