line bore of multiple plates
line bore of multiple plates
(OP)
hello all,
My question is about boring out a hole through 6 plates spaced 3" apart. The plates are 1" thick with the the two end plates 6" thick. On the old drawing I am updating they have a diameter dimension with a g7 tolerance. The diameter dim says to BORE 6X DIA5.0 G7 +0.xx/-0.xx and on the other side of the part is a concentricity call out on the end hole with the datum as the axis of all the holes. The drawing view is a section view to the middle of the holes. (dang after re-reading this even I'm confused now, I'll create a jpg of the view tomorrow at work). Well if anyone can understand this let me know.
My question is this: is there a correct or better way to dimension these holes? They are for a pin that will be inserted through the plates. The pin will support sheaves on a crane. I was thinking that you would have to show concentricity to each hole on the plates and not just the end one.
Thanks a bunch,
Minnyman
My question is about boring out a hole through 6 plates spaced 3" apart. The plates are 1" thick with the the two end plates 6" thick. On the old drawing I am updating they have a diameter dimension with a g7 tolerance. The diameter dim says to BORE 6X DIA5.0 G7 +0.xx/-0.xx and on the other side of the part is a concentricity call out on the end hole with the datum as the axis of all the holes. The drawing view is a section view to the middle of the holes. (dang after re-reading this even I'm confused now, I'll create a jpg of the view tomorrow at work). Well if anyone can understand this let me know.
My question is this: is there a correct or better way to dimension these holes? They are for a pin that will be inserted through the plates. The pin will support sheaves on a crane. I was thinking that you would have to show concentricity to each hole on the plates and not just the end one.
Thanks a bunch,
Minnyman





RE: line bore of multiple plates
Sounds problematic if ASME is invoked then datums on center lines isn't correct.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: line bore of multiple plates
RE: line bore of multiple plates
Still would be nice to see the sketch of your application.
RE: line bore of multiple plates
AM STILL WORKING ON THE DRAWING VIEW JPG
RE: line bore of multiple plates
I strongly prefer it when holes are specified on each, individual drawing. In your case, if a pin must pass accurately through all the holes, it is impossible.
I would show that the holes must be located to some reasonable level of accuracy from a proper datum, and that they must be located with extreme accuracy to each other, thus showing that all must be drilled in one setup, after assembly.
You can use the top face and hole as datums to locate very accurately, the remaining holes. This would be the second block in your FCF. The 1978(6?) standard makes things interesting.
--
JHG
RE: line bore of multiple plates
here is the pic.
just a FYI I am not an engineer just a drafter. I have had some training with GDT but no where near as extensive as you guys.
the concentricity frame used to be on the right pointing to the first plate.
thanks
RE: line bore of multiple plates
First: We don't know what datum A is. It shouldn't be tagged with an imaginary center line, because we can't touch a center line when we're making or inspecting the part, and also because it's ambiguous. There are many features that are shown on that center line and it's unclear which is the real feature to grab onto to establish the datum axis. The datum feature symbol should be tagged with a physical diameter, and then the real datum will be understood to be an axis still (but it will be taken from the diameter tagged with the datum triangle symbol).
Second, once the datum is ironed out, you'd be much better off with the position symbol than concentricity. You stated that you are just trying to align the holes so that a pin can be inserted through there. They might sound like they are doing the same thing, but the way they are defined is different enough to make a significant difference. Depending on the loads of the crane and strength / wall thickness issues, it's possible to also use an MMC modifier with position.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
http://www.gdtseminars.com
RE: line bore of multiple plates
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: line bore of multiple plates