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Lesson (Week) #11,

EGR-110-40, Burgener, Monday November 6th, 2000

Administrative notes and announcements: Nothing (yet)

Don't forget to check your grades.

Handouts: Nothing.

New material: Most of the class tonight will be (was) lab time to begin or continue the dimensioning assignment. I'll demonstrate a few things and let you work some.

Repeated from last week's website:
New AutoCAD Demonstration:
I'll assign 5 drawings from the textbook for dimensioning, next week (see below). Each will have different dimension "settings", and should involve a different "dimension style". One style will have ticks instead of arrowheads, another will have feet and inches intead of inches alone, etc.

All drawings will be bordered by ASIZE, much like you did for the auxiliary view assignment, which is due next class. Each of the 5 dimensioned drawings is to be seen in a separate paper space viewport. You can simply INSERT the completed drawings into your new drawing, and them add the dimensions to it, on a layer named Dimensions. Each of the 5 is to have it's respective dimension style, with all dimensions updated to that dimension style.

This assignment brings up two new concepts I was unfamiliar with before preparing for this lesson, back in '99. I've learned that AutoCAD has the capability to control LTSCALE and DIMSCALE (the size of arrowheads, gaps, text, etc) as a function of the Zoom value of the paper space viewports.

After drawing and dimensioning all the drawings in Model space (don't adjust LTSCALE nor DIMSCALE), toggle to Paper Space (Layout tab), and make a viewport for each drawing, so that each of the 5 can be seen in it's own viewport. Make each viewport active, and in turn, Zoom in or out on each drawing, until each drawing will print out about the same size.

The default value of PSLTSCALE (1), allows the apparent Paper Space zoom scale (remember Zoom XP?) of each drawing to control the lines breaks, NOT the "real" size, as created in Model space. The breaks in the centerlines (or hidden lines) SHOULD appear reasonable, in all viewports.

The next step is to set DIMSCALE to Zero in each Dimstyle, and REGENALL. This SHOULD adjust the DIMSCALE setting for each viewport to be controlled by the viewports Zoom scale. This way, the tiny drawing will have arrowheads and text ligible, and similar to to the biggest drawing. However, I had difficulty making this work. I tried REGEN in each viewport and REGENALL. The only sure way to make the dimensions appear right was to select all the dimensions of a certain dimstyle, change them a different dimstyle, then change them back again to the respective (correct) dimstyle. Only after "re-assigning" them to the proper dimstyle, did they shrink or grow to the correct geometry size.

Instead of doing the above (which I found more difficult than I thought it would be), lets set PSLTSCALE to 0, and leave LTSCALE set to 1. The "broken" linetypes should then be controled by the Linetype scale "factor" via the Properties dialog box (exactly what I've told you NOT to do, so far this class).

The size of the dimension geometry (arrowheads, text height, etc), should be controlled by the DIMSCALE setting for the respective Dimstyle. DON'T set DIMSCALE to zero (for paperspace control).

Notice the screen capture below has suggested DIMSCALE and LTSCALE Factors. All that's left is to choose the proper Linetype (Center, Center2, Centerx2) for the layer.
Those of you with a new AutoCAD LT at home, should have no problem using it for this dimensioning assignment.

The problems will be:
Page 158, FIG. 6-2-C,
page 217, FIG. 7-2-E,
page 41, FIG. 2-6-K,
page 159, FIG. 6-2-E,
and ...

New added info:
For the 5th assignment, how about you insert your choice of either:
The assignment from page 248 Shaft Base (front view only, as shown on week 6 webpage)
The quiz problem from page 166, the Locking Plate (front view only, as shown on week 8 webpage).

In either case above, dimension the front view as close as you can to the way it's shown in your textbook. Omit the section line/s.

Bare with me, folks. We moved the bulk of the furniture (still lots of junk left to move) over the weekend, and I haven't touched this class since the last night. I'd hope to complete this assignment (much of the project from '99 can be used again), but never got around to it. Anyway, I'll update the '99 assignment (see below) and post it within the next couple days. Please check back to this page later.

wk-10-dims.gif Old Dimensioning Assignment, from 1999

Rules and Hints for Dimensioning Assignment
Week #10, EGR 110-40, from fall 1999, for R14.
(hopefully this advise will help you with AutoCAD 2000)

To be able to have a “standard” dimension style, preserve the default style named “Standard”. In case you get the DIMVARs so messed up you lost track of what you changed, you can always restore “Standard” and use it to develop a new dimension style. Be careful not to save any changes to “Standard”.

Each of the 5 drawings should have it’s own unique dimension style(P41, P458, P158, etc). Once you’re satisfied with all the DIMVAR changes (whether by type-in or by the Dimstyle dialog box), save the settings to a new style name, and immediately “update” the dimensions to ensure there are no surprise changes. Be prepared for the concave fillet radius dimensions to change. If they do, simply erase and re-dimensions the fillets.

Guidance, from the old R14 procedure:
(sorry I didn't get this updated for AutoCAD 2000.)
Annotation>Units…>Units>Dimension Precision>to 2 decimals
Annotation>Units…>Units>Dimension Zero Suppression>Leading and Trailing
Annotation>Alternate Units>Enable Units>Units>Scale Linear>1 divided by 25.4
Format>Fit>Text Only
Format>User Defined (to place diameter dimensions outside the circles)
Geometry>Overall Scale (see alternative below)
Geometry>Center>None (to omit the automatic centerlines)

Absolutely NO dimensions are to be exploded or made with DIMASO set to OFF. Doing this defeats the purpose of dimension styles. You can no longer update dimensions merely by redefining the style. The dimensions also will be unable to change as your drawing is scaled or stretched.

Good luck with the few dimensions on this page that have the text placed between the extension lines, but the arrows placed outside. Try “Text Only” fit, or “User Defined”. I ended up copying some dimensions because I couldn’t get the DIMVARS set the right way. Maybe DIMSCALE needs to be low to do it.

Use the Insert Block icon to bring existing files (2 of them) into model space. Also use INSERT to bring the ASIZE title block and border drawing into Paper Space.
Use %%C before the brackets (<>) to force the diameter symbol in the dimension text, if you have to (though I don't think you should have to).
Add text after the brackets when necessary (like for page 158).
Use the Properties icon to revise the dimension text, or to change the applied dimension style, or Linetypescale factor.

Never overwrite the brackets (<>). This will also defeat the dimension styles advantage.
Page 158- I manually made and placed the crosses for the radius dimensions.
Page 158- See your textbook for the radii of the pulleys.

Collected during class:
The Viewport Auxiliary view assignment, page 416 lower left, FIG. 12-3-C. Copy it to the back PC, in the new C:\temp\Burgener-wk10 folder, as usual.

Due next class: Nothing.

Heads Up:
In two more weeks I'll collect the dimensioning /paper space assignment that you're working on tonight.