ARP2
Mechanical
- Dec 10, 2022
- 1
Hi everyone,
New here. Might be a stupid question, but here goes:
I'm currently working on updating our companies drawing standards from BS 308 to BS 8888 (better late than never).
When it comes to hole callouts, we like the intuitiveness of the symbols for counter bores, counter sinks, depth, etc. And also the smallest to largest order in the callouts.
But we also have plenty of examples where we need to define flat bottom holes, occasionally dimension to drill point to maintain minimum wall thickness and define the max drill depth for a tapped hole for the same reason. Sectioning wouldn't be ideal, some drawings would become cluttered with them. So, defining as many holes with a callout would be ideal.
We noticed ISO 15786 in the references (not normative). With it's use of U (flat bottom), Y (to drill tip) and / (tapped hole depth) it seems to cover everything we need. We have a plan that means we won't be overly restrictive on the machinist when not needed.
However, it does seem to contradict BS 8888 and ISO 129-1 in having no symbol for countersink, reusing U for counterbores, and reversing the order of the callout (largest to smallest feature).
Do you think we could use ISO 15786 for the hole callouts, but substitute counterbore, countersink, and depth symbols where applicable and use the order given BS 8888? Also, given that it's only referenced in BS 8888, we're not sure if we'd need to specifically make reference to ISO 15786 on the drawing?
New here. Might be a stupid question, but here goes:
I'm currently working on updating our companies drawing standards from BS 308 to BS 8888 (better late than never).
When it comes to hole callouts, we like the intuitiveness of the symbols for counter bores, counter sinks, depth, etc. And also the smallest to largest order in the callouts.
But we also have plenty of examples where we need to define flat bottom holes, occasionally dimension to drill point to maintain minimum wall thickness and define the max drill depth for a tapped hole for the same reason. Sectioning wouldn't be ideal, some drawings would become cluttered with them. So, defining as many holes with a callout would be ideal.
We noticed ISO 15786 in the references (not normative). With it's use of U (flat bottom), Y (to drill tip) and / (tapped hole depth) it seems to cover everything we need. We have a plan that means we won't be overly restrictive on the machinist when not needed.
However, it does seem to contradict BS 8888 and ISO 129-1 in having no symbol for countersink, reusing U for counterbores, and reversing the order of the callout (largest to smallest feature).
Do you think we could use ISO 15786 for the hole callouts, but substitute counterbore, countersink, and depth symbols where applicable and use the order given BS 8888? Also, given that it's only referenced in BS 8888, we're not sure if we'd need to specifically make reference to ISO 15786 on the drawing?
