Newbie question about alignment

[littleCNCjohn]

I have a quick question about aligning features on different components. For a simple example, suppose a hole passes through each of two parts, both of which will be attached to a third part. I need a pin to be able to slide through the holes (picture). In this case, I guess the correct way to do it would be to use basic dimensions in the drawings of the individual components and then specify the holes’ alignments on an assembly drawing (right?). Another example that I ran into was that a plate on one component had to pass through a slot of a different part. There I divided my allowable tolerances between the two components (resulting in tight tolerances), but is there a way to instead say that the tolerance of the slot is modified by the condition of the plate? Thanks,

John

[jboggs]

I would design it with the final intent in mind. That means noting alignment of holes on the assembly drawing. KISS principle.

[Timelord]

Another way to handle this , if your assembly people are capable, is to manufacture the parts with undersize holes and note on the assembly drawing to drill and or ream at assembly.

Timelord

[littleCNCjohn]

Thanks jboggs and Timelord! I was probably laboring too much under my GD&T book's instructions to minimize the use of notes.

-John

[Kelly_Bramble]

Thanks jboggs and Timelord! I was probably laboring too much under my GD&T book's instructions to minimize the use of notes.

-John

Minimize notes? I've heard lots of interesting personal preferences expressed about how to create an effective engineering drawing for manufacturing and inspection. Notes are awesome and very often the only way to clearly communicate intent.

Use all the notes you need - engineering drawing should be created so that everybody involved in the process can get their job with minimal questions or confusion.

Note away!