TheSwamp
CAD Forums => CAD General => CAD Standards => Topic started by: CADaver on June 28, 2004, 01:02:37 PM
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IMMHO
Information that is necessary to construct the elements depicted in a drawing must be derived from the content of the drawing, not from laying a plastic stick on a wadded up coffee stained 3rd generation print in the field. Scaling a drawing is, at best, a bad guess that asssumes a level of accuracy exists is completely uncontrollable by any one indivdual.
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true.... its close.. but not exact
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Once a paper copy goes outside, the scale is pretty much gone.Set a paper copy outside (especially in the South) and leave it for 30 minutes. Then check the scale. You will be surprised. Kinda like expecting a blur print to be to scale. (yea, right, rolling a sheet of paper around a glass cylinder while shinning a hot, bright light on it and blowing ammonia fumes on it will produce a scale copy.)
Only a few ways to get a true scaled copy. Contact photo print on 7mil stable base mylar or a correctly produced e-copy. I can burn you a scaled blue line using a flat bed exposure unit wit a glass lid and a big ole vaccuum pump, but once you walk outside, all bets are off.
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true.... its close.. but not exact
Most often it's not even close.
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Once a paper copy goes outside, the scale is pretty much gone.Set a paper copy outside (especially in the South) and leave it for 30 minutes. Then check the scale. You will be surprised. Kinda like expecting a blur print to be to scale. (yea, right, rolling a sheet of paper around a glass cylinder while shinning a hot, bright light on it and blowing ammonia fumes on it will produce a scale copy.)
Only a few ways to get a true scaled copy. Contact photo print on 7mil stable base mylar or a correctly produced e-copy. I can burn you a scaled blue line using a flat bed exposure unit wit a glass lid and a big ole vaccuum pump, but once you walk outside, all bets are off.
Even that assumes the plotter have been recently (and accurately) calibrated recently to plot to scale, and the media used to produce the plot was stable.
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Plotter won't really do it. I'm going back to the
Golden Days" of the contact photo lab. Big ole vacuum frame, pin light, photo screen, 7mil Dupont film!! Ah!! the last days of accuracy.
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Just add dimensions to the drawing! Who needs to draw to scale?! :twisted:
*M-dub runs for cover*
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Plotter won't really do it. I'm going back to the
Golden Days" of the contact photo lab. Big ole vacuum frame, pin light, photo screen, 7mil Dupont film!! Ah!! the last days of accuracy.
What was the source data media? you needed something to photo.
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Well, we do have a disclaimer note that basically states ... "When referencing these drawings, the printed dimensions override any scaled dimensions. Do not scale these drawings for dimensions."
Of course everyone scales the dang things.... so why not at least attempt to draw (and plot) them accurately.
Incedently we check our plotted drawings for scale factors on a routine basis.
A number of our contractors have also began having their construction plans laminated to prevent those coffee spills from damaging the plans in the field.
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Just add dimensions to the drawing! Who needs to draw to scale?! :twisted:
*M-dub runs for cover*
Therein lies the confusion. You saw PLOT to scale and thought it meant DRAW to scale. Two completely different aspects of production.
"Drawing" to scale is required for accurate construcability, "plotting" to scale is not. The accuracy of "drawing" produces accurate dimensions on that drawing. The construct should be accomplished from the dimesions, not from laying a plastic stick along a plot.
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Cadaver, in the "good ole days" we had our own aircraft and kelsh stereo plotters.We produced color separated maps for the Corps of Engineers. Did the photoghrapy (You haven't lived until you've processed a 500' roll of color film by hand!!) and all of the compilation in house. Then I'd get the data and do all of the engraving and lab work. Kept me busy and off the streets.
Source data then was the 7mil scribe coats. All photocopy was by contact print. All data had to be within 0.001" of compilation or it was rejected. All line widths had to be within 0.001" of standard or work was rejected. I still like to draw index contours at 0.008" anf intermediate contours at 0.004". Maybe this is why I am such a stickler on accuracy. In mapping we were held to the wall by stiff, exact standards. An idea of drawing layers never confused me. We used to call them "overlays". No real differance.
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Cadaver, in the "good ole days" we had our own aircraft and kelsh stereo plotters.
Yikes, high-dollar hardware there.
We produced color separated maps for the Corps of Engineers. Did the photoghrapy (You haven't lived until you've processed a 500' roll of color film by hand!!) and all of the compilation in house. Then I'd get the data and do all of the engraving and lab work. Kept me busy and off the streets.
Source data then was the 7mil scribe coats. All photocopy was by contact print. All data had to be within 0.001" of compilation or it was rejected. All line widths had to be within 0.001" of standard or work was rejected. I still like to draw index contours at 0.008" anf intermediate contours at 0.004". Maybe this is why I am such a stickler on accuracy. In mapping we were held to the wall by stiff, exact standards. An idea of drawing layers never confused me. We used to call them "overlays". No real differance.
I did a little bit of map work fo COE when I first got in the business, ink on mylar. I'm so glad I got out before having to do contact prints.
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Contact prints were so much easier than the ink on mylar. Especially with ruling pens and railroad pens. I hit a point where I had the clients requesting that their jobs be scribed (engraved). I could do that faster. (didn't have to wait for the dang ink to dry) plus I then could use screens on the composite positives to really dress the package up.Even figured a way to add color to the mylar prints using the QuickProof dyes. Sold a bunch of them. Local firms really liked that.
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Speaking of scaling, we once had a contractor call in telling us our Electrical Single/One Line Diagram was not to scale. It was off by 200' and we needed to correct the situation before he could continue. Needless to say, this contractor was booted off the project. Thats like asking someone how long the building is and he/she puts a plastic scale on the monitor to measure it. :lol: :lol:
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Contact prints were so much easier than the ink on mylar. Especially with ruling pens and railroad pens. I hit a point where I had the clients requesting that their jobs be scribed (engraved). I could do that faster. (didn't have to wait for the dang ink to dry) plus I then could use screens on the composite positives to really dress the package up.Even figured a way to add color to the mylar prints using the QuickProof dyes. Sold a bunch of them. Local firms really liked that.
i love autocad
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Me too
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When things are set up right (for me), AutoCAD Rocks. :D :D
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I fell in love with autoCad when they told me that I could throw my french curves away.
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Keith noted that there is a disclaimer on their drawings to the effect “do not scale these drawings only use figured dimensions”. All of our construction drawings have this disclaimer on them. All of our A1 plots are plotted “Extents” (in paper space), so the finished plot may well be close to 1:100 or 1:50. The exact scale of the plot is irrelevant so long as there are enough figured dimensions to enable the bluntest tools in the box construct the building, slightly unfair, but you know what I mean.
For our own use, we frequently produce a set of A3 prints as desk copies as they are easier to handle than A1. Some contractors will also request A3 prints for the same reason.
The best example I have of a contractor trying to scale prints was a ground worker bringing a dirty soaking wet handful of near pulp and claiming that he could not set out the foundations from these prints!
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I fell in love with autoCad when they told me that I could throw my french curves away.
For me it was the Leroy set and the pen cleaning station.
"You mean I no longer have to spend every afternoon 3 nuckles deep in black water?!?!?!?!?"
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We generally address this issue by putting right on the drawing:
All dimensions shown are <unit of measurement>.
and
Do not scale drawing.
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We generally address this issue by putting right on the drawing:
All dimensions shown are <unit of measurement>.
and
Do not scale drawing.
Then plotting to scale is a non-issue, right?
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All dimensions in millimetres unless otherwise stated
Do NOT scale. If in doubt ask
is there anything unclear about that ?
if the drawing does not contain enough data to manufacture the part then the drawing is incomplete, and therefore, incorrect.
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Then plotting to scale is a non-issue, right?
Not when it is required by law AND when the contractor will reject the plans if they are not plotted to scale.
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Then plotting to scale is a non-issue, right?
Not when it is required by law AND when the contractor will reject the plans if they are not plotted to scale.
Based on the other thread, you can't prove it wasn't.
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if the drawing does not contain enough data to manufacture the part then the drawing is incomplete, and therefore, incorrect.
Bingo, we have a winner, to pick up your prize, call 713-555-pintobeans.
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if the drawing does not contain enough data to manufacture the part then the drawing is incomplete, and therefore, incorrect.
You are absolutely right, but if the drawing contains even a meager amount of data that adequately describes the model, and it can be built using nothing more than basic construction techniques it is indeed correct.
Plotting to scale is a basic idea that produces viable and reproducable results that any monkey with a masuring tape can gather additional information from. If it is not to scale then he cannot.
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Plotting to scale is a basic idea that produces viable and reproducable results that any monkey with a masuring tape can gather additional information from.
As long as he doen't care that the additional information is inaccurate. But then he's only a monkey.
If it is not to scale then he cannot.
If he's looking for "ballpark" numbers (which is the BEST that can be derived), he can interpolate from any drawing, "to scale" or otherwise.
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Plotting to scale is a basic idea that produces viable and reproducable results that any monkey with a masuring tape can gather additional information from.
As long as he doen't care that the additional information is inaccurate. But then he's only a monkey.
If it is not to scale then he cannot.
If he's looking for "ballpark" numbers (which is the BEST that can be derived), he can interpolate from any drawing, "to scale" or otherwise.
As are most contractors, and managers
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As are most contractors, and managers
ummm.... which?
"Monkeys" or "looking for "ballpark" ??
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both
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both
hmmm... I think I've been insulted... twice... I think... :lol:
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Surely not ....