checking that a drawing has all the required dimensions 2

[Ksplice]

Hi,

was wondering if anyone has a good method of checking if a complicated mold drawing has all the required dimensions to make the part. especially if profile dimensions are applied to some features.

 

[KENAT]

Well, I used to start of with the overall shape/profile and make sure all dimensions were there. Then I'd go through each feature at a time, starting on one view (obviously you have to jump to other views as features demand it) and working my way round the drawing.

Use colored pencils or similar to tick them off as you go. I used the typical yellow for keep, red for change/add/delete and blue for notes to my self, non mandatory suggestions...

When you say profile dimensions, do you mean the model is referred to and a general profile tol applied?

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[drawoh]

Ksplice,

If you have a drawing of the part, use it to build a 3D model in CAD. Reproduce the drawing in your CAD package. This will force out a lot of erros and omissions.

JHG

 

[ewh]

Granted, it isn't the method used by old-time drawing checkers, but I have seen drawoh's suggestion used often to great result. Irregular features that are normally read from the model (and not defined on the drawing) are imported into the reproduction. If some part of the definition is missing from the drawing, the resulting model will not match the original (if it can be completed at all).

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[CheckerHater]

Old-timers could try and re-create the geometry of the part on paper relying entirely on dimensions. No cheating - don't try to measure anything!

 

[ewh]

That was one shortcoming of board checking - just because the dimension was there, was it a truely correct dimension? I've never had a checker check the actual vellum or mylar (with a scale), always bluelines (which are often subject to paralax distortion). Even the original vellums would shrink and stretch depending on temp and humidity.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[ajack1]

One of the shortcomings but also one of the pluses.

You could draw shims in for example so they would show up on a drawing or if you had a long bar a couple of break loops and an overall dimension was all that was needed. Some of the poetic license that was allowed on paper drawings is not on CAD or at least not if the CAD is to be used in any meaningful way.

 

[ewh]

Not necessarily. You can adjust the line width to represent shims, and many CAD packages let you break up views into several segments, allowing for the detailing of a very long piece on a relatively short drawing. Any dimensions are associated to the same solid geometry. No poetic license needed, just knowledge of what the software is capable of and how to use it. I don't consider such use to be un"meaningful".

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[ctopher]

You can also show the drawing to a machinist for his input.

Chris
SolidWorks 10 SP5.0
ctopher's home
SolidWorks Legion

 

[jadams67]

I have found that no matter how well you believe you have dimensioned a part, there is still something missing. A machinist might want an angle measured a different way or might want a different dimension all together from what you put down.

But my method has been stated above. Start with outside then move to the features.