An odd thing about CAD...

(aside from blank messages :-)

I use DeltaCAD, a simple 2D replacement for the traditional T-square
and triangles, to make patterns for parts, from a 56" rib to itty-bitty
things for home-made clocks, tiny steam engines and similar stuff. And
I talk about it, too. If you hope to share information at a distance
you need good drawings and a simple CAD program is miles ahead of
old-fashioned drafting.

That produces a lot of mail, almost all of it from guys telling me why
they DON'T use CAD, or at least, not DeltaCAD. Such as the message I
received last night in which the feller explained that the reason he
didn't like DeltaCAD -- and only had it so he could print out my
drawings of VW conversion parts -- was because he was accustomed to
working in fractional inches.

"In the time it takes me to convert 27/64ths to decimal and get it
typed in," he wrote, "I could have drawn it a dozen times with a
drafting scale."

I had to think about that for a while. A private answer would have
been more polite but if one person thinks DeltaCAD can't handle
fractional inputs then others might, too. And the truth is, it handles
them just fine. Want a line 27/32nds in length? Then select the LINE
function, indicate the point of oirgin with your pointer and type in
27/32.

One and nine-sixteenths? Then type in 1 (space) 9/16. Two feet, three
and three-sixteens would be entered as 2'3 3/16.

I can appreciate the feelings some guys have when they're faced with
converting a 1920's drawing into a digital format. Back then,
everything was in fractions of an inch and American Wire Gauge, neither
of which is in common usage today. But DeltaCAD, with which I have no
relationship other than as a satisfied customer, really IS handier than
your T-square, triangles and drafting scale. The odd thing is that so
few guys my age think so and I really can't understand why. The
complete manual is only 218 pages long and most of that is white-space.
In fact, compared to other CAD software DeltaCAD is so simple most
guys start turning out usable drawings without ever reading the manual.

-R.S.Hoover

wrote:

(aside from blank messages :-)

I use DeltaCAD, a simple 2D replacement for the traditional T-square
and triangles, to make patterns for parts, from a 56" rib to itty-bitty

So fess up, what do you print your 56" rib out on ?

Rob .. a happy DeltaCAD user

..ps If I can use DeltaCAD, anyone can and I only had to peek at the
manual a couple of times!

I don't use "DeltaCAD", I use "TurboCAD". Which is probably about the same
thing. New CD's of a recent version can be had on EBay for $10 or so.

Not only is it better than manual CAD, I can take a DXF file to Kinkos and
print it out full size. I printed out a side view of my MoHawk tube and
fabric fuselage (16 feet long, all one piece of paper), then just stapled it
to my workbench and welded tube over the top of it. A really easy way of
getting things exact.

I did a drawing of a back plate of a home made PSRU. Did it full size, with
each of the holes to be drilled marked by a dot. Glued the paper to the
aluminum plate, and started drilling and cutting. Again it was easy, and the
holes are within a few thousandths of perfect.

Robert Schieck wrote:

So fess up, what do you print your 56" rib out on ?

-----------------------------------------------------------------------------------

Regular typing paper :-)

Select a new LAYER called 'Grid' and draw a grid atop the finished
drawing. I used a 2" square and selected THIN pale blue lines, printed
the rib 1:1, which took 6 sheets, then glued them together aligned on
the blue lines.

If you don't have a light-table, attach a small weight to a length of
black thread and tape it to the OUTSIDE of a picture window or sliding
glass door. Gravity does its thang and the black line of the thread
becomes your vertical alignment guide, easily visible through the paper
when in contact with the INSIDE of the glass. The regular (ie, black)
lines of the drawing are clearly visible and each sheet is fairly easy
to align in the horizontal plane. But for maximum precision, you may
print TWO copies of the drawing and OVERLAP the sheets, using the blue
grid for both vertical and horizontal alignment.

Printing was done on a garden variety HP Deskjet 930c. Using an
optical comparitor, accuracy is better than .001" over 8". If you wish
to verify the trammeling of your paste-up, compare your 2" grid to a
steel tape as the paste-up progresses. To transfer that degree of
precision to the work-piece, use spray-glue to attach the pasted-up
pattern to a sheet of aluminum, use an optical center-punch to prick
the centers of your tooling holes and check that with a regular
trammel.

Crude as the method above may appear, the dimensional accuracy of such
a pattern will typically exceed the standard of precision available to
the typical home-builder. Although maybe not the first time they try
it :-) Parallax plays a role in the accuracy of your paste-up as does
paper quality in your printing. But on average, ribs are pretty easy
compared to a 4x4 paste-up for a firewall or bulkhead.

-R.S.Hoover

wrote:
Robert Schieck wrote:

So fess up, what do you print your 56" rib out on ?

use spray-glue to attach the pasted-up
pattern to a sheet of aluminum,
-R.S.Hoover


I'll add just one point. In my experience, spray glue won't work if
you're makeing steel pieces and have to grind it down to the line.
Cutting the metal gets it hot, and that melts the glue. I've used a
little paint instead. I have a couple little cans of Killz white primer
that I keep around. Spread a thin layer using some scrap paper or
whatever's handy. It will come off easier later if the metal still has
the shipping oil on it, but it will still stick plenty well enough to
make the part.

I've also used the Kinko's trick mentioned earlier, but they don't like
the CAD formats and only play nice with PDFs. And then they didn't like
the 8' airfoil of the Delta. Finally settled on printing it half size
and then blowing it up to full size using the blueprint copier they all
have.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

But DeltaCAD, with which I have no
relationship other than as a satisfied customer, really IS handier than

your T-square, triangles and drafting scale. The odd thing is that so
few guys my age think so and I really can't understand why.

The sad thing is that guys your age can probably learn CAD faster than
the average high school grad. They most likely remember a bit of 8th
grade geometry from 40+ years ago. :-)
==============
Leon McAtee
I too recommend DeltaCad for the masses

On 24 Nov 2005 16:17:51 -0800, wrote:

(aside from blank messages :-)

I use DeltaCAD, a simple 2D replacement for the traditional T-square
and triangles, to make patterns for parts, from a 56" rib to itty-bitty
things for home-made clocks, tiny steam engines and similar stuff. And
I talk about it, too. If you hope to share information at a distance
you need good drawings and a simple CAD program is miles ahead of
old-fashioned drafting.

That produces a lot of mail, almost all of it from guys telling me why
they DON'T use CAD, or at least, not DeltaCAD. Such as the message I
received last night in which the feller explained that the reason he
didn't like DeltaCAD -- and only had it so he could print out my
drawings of VW conversion parts -- was because he was accustomed to
working in fractional inches.

"In the time it takes me to convert 27/64ths to decimal and get it
typed in," he wrote, "I could have drawn it a dozen times with a
drafting scale."

I had to think about that for a while. A private answer would have
been more polite but if one person thinks DeltaCAD can't handle
fractional inputs then others might, too. And the truth is, it handles
them just fine. Want a line 27/32nds in length? Then select the LINE
function, indicate the point of oirgin with your pointer and type in
27/32.

One and nine-sixteenths? Then type in 1 (space) 9/16. Two feet, three
and three-sixteens would be entered as 2'3 3/16.

I can appreciate the feelings some guys have when they're faced with
converting a 1920's drawing into a digital format. Back then,
everything was in fractions of an inch and American Wire Gauge, neither
of which is in common usage today. But DeltaCAD, with which I have no
relationship other than as a satisfied customer, really IS handier than
your T-square, triangles and drafting scale. The odd thing is that so
few guys my age think so and I really can't understand why. The
complete manual is only 218 pages long and most of that is white-space.
In fact, compared to other CAD software DeltaCAD is so simple most
guys start turning out usable drawings without ever reading the manual.

-R.S.Hoover

hey bob. do you realise that america has been a metric country for
over 103 years now. are you going to get the message soon?
:-)
Stealth Pilot

Stealth Pilot wrote:

hey bob. do you realise that america has been a metric country for
over 103 years now. are you going to get the message soon?
:-)
Stealth Pilot
------------------------------------------------------------------------------------------

Hey ozzie, did you realize that the American Congress authorized the
use of the metric system in 1866? Or that the SI system became our
official standard for weights & measures when the United States signed
the original international Metric Treaty in 1875?

America uses a mix of traditional and SI units because Congress
provided no funds for conversion nor penalties for failing to do so and
indicated how little importance they placed on the matter by exempting
themselves and their functions (such as the Library of Congress) from
any legal requirement to observe the metric standards.

So I guess the answer to the first part of your question is, yes. And
since we seem to have gotten the message about a hundred years before
you did, the answer to the second appears to be moot. But perhaps the
most important part of this exchange has to do with the fact DeltaCAD
works equally well with meters or inches. And we were talking about
CAD software instead of how many kangaroo hops there are in a nautical
mile :-)

-R.S.Hoover

And we were talking about
CAD software instead of how many kangaroo hops there are in a nautical
mile :-)

-R.S.Hoover

Depends on whether it is a male or female ;-)

how many kangaroo hops there are in a nautical
mile :-)

Hi all,

Contrary to the statute mile, the nautical mile has nothing to do with
the Imperial system a few countries in the world are still using since
Colonial days ;-)

The nautical mile is based on the cicrcumference of the Earth. One NM
corresponds to a one minute angle along a big circle.
It is thus easy to relate distance to latitude and longitude coordinates.

That's why every nation in the world is (and will keep) using it for
navigation by air or sea.

Regards,
Gilles Thesee
Grenoble, France
Metric since day one

http://contrails.free.fr