View Full Version : Trying to decipher drawing - Hole Size
RCW 9th July 2008, 04:05 PM Can somebody help this electronics boy out?
I have a drawing of an identification plate and there is a dimension arrow pointing to a hole. It has a large "+" sign with the number 3 in the upper right quadrant of the plus sign. I'm assuming this is a reference to an actual hole size but I cannot find a reference to a spec anywhere in the documentation for this part.
Can anybody clarify what is being referenced here?
justncredible 9th July 2008, 04:16 PM Is it a assembly drawing, or blueprint? I am thinking you have a assembly drawing and the 3 will be to the step you need to follow. The big + might relay the section of the completed assembly, or maybe a section.
If it is a blueprint, I have never seen a big +, maybe scan it and post the pic. If you can not you will need to provide as much details as possible. It could be a ref to a hole chart. I know Cat does that on prints.
RCW 9th July 2008, 04:46 PM Is it a assembly drawing, or blueprint? I am thinking you have a assembly drawing and the 3 will be to the step you need to follow. The big + might relay the section of the completed assembly, or maybe a section.
If it is a blueprint, I have never seen a big +, maybe scan it and post the pic. If you can not you will need to provide as much details as possible. It could be a ref to a hole chart. I know Cat does that on prints.
1. It is a "blueprint" for a piece part. It is not an assembly drawing.
2. There is not a hole chart associated with the drawing.
3. I have attached two pdf files. I now have found 2 different drawings that call out the hole the same way.
The drawing dates back to 1973 so possibly this was an old-school method for specifying hole dimensions?
justncredible 9th July 2008, 04:55 PM TYP means typical, so you would use the block tol. for a whole number. Most of the time it is located in bottom right corner but may be located in top right corner.
x = .010
.x = .005
.xx = .003
.xxx = .001
They are kinda listed like that in the block. Sometimes they will have specs called out on the drawings, such as see spec xxx.xx to interpret this drawing.
Stijloor 9th July 2008, 05:05 PM TYP means typical, so you would use the block tol. for a whole number. Most of the time it is located in bottom right corner but may be located in top right corner.
x = .010
.x = .005
.xx = .003
.xxx = .001
They are kinda listed like that in the block. Sometimes they will have specs called out on the drawings, such as see spec xxx.xx to interpret this drawing.
In addition....
They are usully provided as plus/minus tolerances.
Be cautious! The problem is that these tolerances are drawing-specific and are not standardized. So what's specified one one print, may not be the same on another.
That's why engineers should commit to an accepted standard such as ASME/ANSI Y14.5M-1994.
Hope this helps.
Stijloor.
RCW 9th July 2008, 05:16 PM TYP means typical, so you would use the block tol. for a whole number. Most of the time it is located in bottom right corner but may be located in top right corner.
x = .010
.x = .005
.xx = .003
.xxx = .001
They are kinda listed like that in the block. Sometimes they will have specs called out on the drawings, such as see spec xxx.xx to interpret this drawing.
I can't apply a tolerance if I don't know what the nominal value is. THAT'S the problem.
Stijloor 9th July 2008, 05:19 PM I can't apply a tolerance if I don't know what the nominal value is. THAT'S the problem.
If it's not on the print(s), then you need to do the obvious and talk to engineering.
If this is a customer's drawing, then someone was asleep at the wheel during contract review.
Stijloor.
RCW 9th July 2008, 05:23 PM If it's not on the print(s), then you need to do the obvious and talk to engineering.
If this is a customer's drawing, then someone was asleep at the wheel during contract review.
Stijloor.
It's a customer's drawing.
With regards to contract review of this, I don't think they can count up to 3 so that's why they missed it. :lol:
Stijloor 9th July 2008, 05:26 PM It's a customer's drawing.
With regards to contract review of this, I don't think they can count up to 3 so that's why they missed it. :lol:
I feel your pain and wish you strength...:agree:
Stijloor.
Frank T. 9th July 2008, 05:31 PM RCW,
Would the "plus" sign actually represent two slits, made to look like a plus sign. I ask because I have seen something similar on an old westinghouse print.
RCW 14th July 2008, 04:06 PM Finally found the answer......
The "code" comes from the NAS 523 spec for rivet installation.
Stijloor 14th July 2008, 04:42 PM Finally found the answer......
The "code" comes from the NAS 523 spec for rivet installation.
Thank you!
Is it this (http://aero-defense.ihs.com/document/abstract/QSTTCAAAAAAAAAAA) spec?
Stijloor.
RCW 14th July 2008, 05:30 PM Thank you!
Is it this (http://aero-defense.ihs.com/document/abstract/QSTTCAAAAAAAAAAA) spec?
Stijloor.
That's the one. Actually, someone here found the callout to this spec on another drawing for the same customer but for a completely different product.
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