Using multiple arrows for the same tolerance
Using multiple arrows for the same tolerance
(OP)
Hey all,
I am wondering if it is acceptable to use the method shown to indicate the same tolerance to the B datum for multiple beams in my assembly.
Thank you.
I am wondering if it is acceptable to use the method shown to indicate the same tolerance to the B datum for multiple beams in my assembly.
Thank you.





RE: Using multiple arrows for the same tolerance
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Using multiple arrows for the same tolerance
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Using multiple arrows for the same tolerance
Dean
www.d3w-engineering.com
RE: Using multiple arrows for the same tolerance
Dean3W: The features that this will be applied to are horizontal beams (5 of them). The datum is referenced off of a bar (on the right) where the bar on the left and a few others above are being related with the parallelism tolerance. Unfortunately I can't really post anymore of the structure.
RE: Using multiple arrows for the same tolerance
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Using multiple arrows for the same tolerance
RE: Using multiple arrows for the same tolerance
The method of showing parallelism FCF with multiple leaders is absolutely legal. You can take a look at figs. 9-4 and 9-6 in Y14.5-2009 standard to see how this is done with runout FCF's as an example.
The other question (already mentioned by Dean) is how capable datum feature B is to serve as a primary datum feature for parallelism callout.
And the second thing is, whether the parallelism is the tolerance you would really like to use. I do not want to go too far beyond the scope of your original question, but you have to keep in mind that parallelism does not locate, so this means that on your print there is no control of a distance between datum feature B and the other bars - unless we can't see it. If that is fine for you, then just forget about what I have just written, but if it is not, then profile of a surface would seem to be a way to go.
RE: Using multiple arrows for the same tolerance
Okay it's good to see another person supporting this and I actually found some other figures with multiple arrows the other day when I was looking through the standards.
I read about the profile tolerance and I changed the bottom beam (left) to a profile tolerance since it seems like a much better way to tolerance the piece. I have left the rest of the beams with a parallelism tolerance, but I have dimensions on those.