Re: Chap 3A

[tkat@tkat.com]

There's one feature I left out. That's the top 15° chamfer line.
Wouldn' tbe hard except the center of the large arc won't show up on
the dwg.

My guess right now is that it can be done w/ layers --- as soon as I
figure out how to use them. Howzabout bringing up a new layer, drawing
a complete 1.849R cir. Constructing a perp line from elevation view to
the C/L of the top view. Select Cir->ctr/point and constructing the
inner cir.

Trim it to the reqd arc and then move it back to the orig layer. That
should work but it seems cumbersome.

Any old hands out there care to stick in yer 2 cents worth?
Particularly w/ instructions on how layers work.

Yeah, I know 2.875-1.849=1.026 as the x co-ord ctr [Google calc] but
I'd like to know how to do it via drafting only.

Ciao,
Tkat

"Everybody crashes, some get back on, some don't, & some can't."

[RowlandCarson]

At 2005-04-26 14:19 -0700 tkat@tkat.com wrote:

>There's one feature I left out. That's the top 15° chamfer line.
>Wouldn' tbe hard except the center of the large arc won't show up on
>the dwg.

Tkat - here's my immediate response to the problem.

Choose Graphic / Measure tool and measure the
arc. As measure wants 2 elements to work on, I
clicked first on the horizontal centre line. This
gave the following in the floating Information
window:

TypeLines
Pen1
Intensity100%
StyleDashdot
Color0, 0, 0
Width0.250
Group0
Layer1
Scale1:1
x0-3.441Inch
y05.650Inch
x10.521Inch
y15.650Inch
Length3.962Inch
Angle0.000°
-
TypeArc
Pen2
Intensity100%
StyleSolidline
Color0, 0, 0
Width0.350
Group0
Layer1
Scale1:1
xm-1.026Inch
ym5.650Inch
r1.849Inch
Start angle116.804°
End angle243.196°
Contour4.078Inch
-
Intersection Points
xs10.822Inch
ys15.650Inch
xs2-2.875Inch
ys25.650Inch
Distance0.000Inch
------------------------------

This is after I moved the plan up 4", of course,
so all the y co-ordinates are offset by that
amount.

So, the centre of the arc is x = -1.026 & y = 5.650.

Pick line type 3 (dash-dot) & draw a line at an
angle, starting at -1.026, 5.65 with angle 90 and
length 1.

Trim it in freehand selection mode to look a nice
length above & below the centre line.

Switch to auto selection mode & draw a
construction line from the top edge of the
chamfer in the elevation, angle 90, length 5.

Switch back to line type 1 (solid) & choose Arc defined by centre & radius.

Click the centre point as drawn above.

Click the intersection of the horizontal centre
line and the construction line from the elevation
drawn above, for the radius.

Click the intersection of the vertical centre
line and the upper and lower edges respectively
for the start and end angles.

Choose Trim / Split and split the arc at both top & bottom edge lines.

Choose Delete / Delete Object and get rid of the end whiskers of the arc.

Delete the 5" construction line between plan & elevation.

>My guess right now is that it can be done w/ layers --- as soon as I
>figure out how to use them. Howzabout bringing up a new layer, drawing
>a complete 1.849R cir. Constructing a perp line from elevation view to
>the C/L of the top view. Select Cir->ctr/point and constructing the
>inner cir.
>
>Trim it to the reqd arc and then move it back to the orig layer. That
>should work but it seems cumbersome.
>
>Any old hands out there care to stick in yer 2 cents worth?
>Particularly w/ instructions on how layers work.

I'm not really clear why you needed to go to
another layer to do this; without actually trying
this (agreed cumbersome!) procedure I don't see
why it shouldn't work OK in the working layer.
All you'd need to do would be delete the
construction circle when you're finished with it.

>Yeah, I know 2.875-1.849=1.026 as the x co-ord ctr [Google calc] but
>I'd like to know how to do it via drafting only.

In CADintosh, it's often much handier to use the
calculating ability of the text entry line than
to figure out an elegant geometrical way to do
things! But stuff like an arc through 3 points is
much easier to do with the CADintosh tool than it
ever would be with pencil & paper.

Having written that, here's a completely
different way to skin this particular cat which
is mostly "drafting".

In the first place, instead of drawing an arc
through 3 points, draw a complete circle thorugh
3 points instead. Draw the vertical line through
the circle's centre using the auto select mode
(hover near the circumference of the circle, not
the centre) to place it. Now the centre of the
circle is marked, you can convert it to an arc.
Split the circle at the top and bottom edges of
the part, then throw away the scrap t leave the
arc. Draw the second arc, using the centre just
produced and the construction line from the
elevation as described above.

I think on reflection this is a simpler and more
elegant way to achieve the same result - but
maybe all the natter above may answer other
questions even if it isn't the right answer for
this one!

regards

Rowland
--
| Wilma & Rowland Carson
| ... that's Rowland with a 'w' ...

[tkat@tkat.com]

Thank for the review.

I was wondering what use the measure tool was. Several of your methods
are more elegant than a layers approach.

But remember how this all started. I'm a interested rookie. I'm
"going to school" on you. ;^)

Tkat

Artificial intelligence is no match for natural stupidity.

[RowlandCarson]

At 2005-04-26 14:19 -0700 tkat@tkat.com wrote:

>Any old hands out there care to stick in yer 2 cents worth?
>Particularly w/ instructions on how layers work.

Tkat - I will upload a drawing with some layer stuff on it. It was
made to check the geometry needed to add gas springs to a drop-down
trailer ramp, so I wouldn't strain my back so much every time I
closed it.

It's got various views on different layers, accessible by the layer
filter palette. You can also use the layer pop-up menu found among
the items at bottom left to switch between layers. Note that (if I
remember right) the active layer is always visible irrespective of
the layer filter chosen, which can be confusing at times.

Note that this was not really designed for others to understand - I
can hardly remember myself all that I did as it grew like Topsy, but
it provides a good playground for exploring layer effects.

The drawing started out as a feasibility study, then helped to choose
the strength of gas spring with the aid of an Excel file (not shown!)
and finally provided drawings for the welder to construct the
required fittings, which were slightly different from my original
conception.

regards

Rowland
--
| Wilma & Rowland Carson
| ... that's Rowland with a 'w' ...