Basic Dimension with no GD&T

[GreenMindmn]

Can you use a basic dimension when no GD&T is used? ie I want to use a linear basic dimension on a spring assembly in order to denote the ideal lengths. I personally would not consider this a reference dimension.

Please let me know if that is unclear.

 

[looslib]

Does the spring length have a tolerance?
Basic dimensions depend on the GD&T callout to give the part tolerance.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[KENAT]

I don't think a basic dimension would be appropriate in your application.

I actually think reference may be the correct option but am not sure from your description. You say ideal length, what do you want this information shown for, this may help someone answer your question.

KENAT, probably the least qualified checker you'll ever meet...

 

[TheTick]

I second for using reference dimensions. Basic dims not appropriate.

 

[fcsuper]

Green,

I agree with the others. Is there a reason you feel you need to keep these dimensions as spec's? If there is a requirement within the assembly of two parts, perhaps this dimension belongs at that higher level assembly drawing?

Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group

 

[Heckler]

Is the Spring Assembly defining the manufacture of the Spring or is it other parts assembled including the spring?

If this is a drawing to define a spring then you would give a length with ends included then a tolerance.

If this is an assembly and this dimension has to be inspected then you would have to roll up all the part tolerances that make up this length. Then allow for realistic assembly tolerances.

If this is just a dimension for the assembler to spot check then it should be reference.

That's the world according to Heckler

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 3.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)

(In reference to David Beckham) "He can't kick with his left foot, he can't tackle, he can't head the ball and he doesn't score many goals. Apart from that, he's all right." -- George Best

 

[powerhound]

I scanned through the responses and I don't think anyone answered your question. The answer is "No" you cannot use basic dimensions without GD&T. I presume that you mean the use of a Feature Control Frame when you refer to the use of GD&T.

What could possibly be so complicated about the length of a spring that you feel you need to control it with something other than a plus-minus tolerance? If I stick with the information you provided in the original post, I would say just put a plus-minus tolerance on it. If you were to put a basic dimension there, you would still need a tolerance in the form of a feature control frame.

Powerhound
Production Supervisor
Inventor 11
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[ctopher]

GreenMindmn,
As you write "an ideal length". Springs are dynamic. If you purchase a spring, there is a spec with it that indicates compression and the 'stretch' tolerances of the spring.
If you add a basic dim or GD&T, you will cause more work and trouble than it's worth.

Chris
SolidWorks 07 3.0/PDMWorks 07
AutoCAD 06
ctopher's home (updated 04-21-07)

 

[dingy2]

No, I would not suggest using basic dimensions without using GD & T.

Basic dimensions are theoretical dimensions and if placed on a feature rather than say, a datum target must have a feature control frame for the applied feature tolerance.

Dave D.

http://www.qmsi.ca

 

[tk369]

look in the standard. paragraph 1.3.9, the definition of 'dimension, basic' tells us that a basic dimension is toleranced by either tolerances on other dimensions, a feature control frame, or in a note.

a stand-alone linear dimension cannot be basic.

 

[GreenMindmn]

Thank you everyone for all the responses. I now agree that a basic dimension is not for use in this situation.

The assembly has a graphite brush and the dimensions in question do not have tolerances. The baseline is part of the carbon that varies when installed. This these dimensions are only used for informational purposes so should be reference dimensions.