What is the correct way to draw this object? each dimensions?

[Sengna]

I am not sure what this called, i see a lot for HVAC duct detail drawings. i was wondering if there a rule or formular for the distance between each line (gap with my red mark), i found one of the drawing, i checked the dims: 1st gap was 3/8", 2nd 7/16", 3rd 1/2".....Is there any online source for my own reference that someone can suggest me? tried to google online but can't think of word to describe.

[JD Mather]

That is called a transition piece (rectangle to round) development.

 

Search for on the terms "developments" and "transition".

A search should turn up many examples

 

FIG 19.35-4.dwf

 

Here is the layout of a general solution.

 

Note that the correct solution is an arc length, then flattened out.

You would take these from the top view as they are not true length in the view you have shown.

 

Of course, with modern 21st century CAD tools, you simply model the finished part and the CAD tool gives you the Flat Pattern development.

An in-depth analysis would show that the classical method is a "fudge" anyhow.

[rkent]

I have the feeling you want to know how to draw exactly what you have shown and not how to draw the development. You have shown a square to round transition and showing that on an HVAC drawing is meant as a representation of what is needed rather than showing the tradesman how to make it. As such you can just fake it and the fewer the lines the better, just enough to get the point across. The lines represent the bend lines that would be required to actually form the piece with more bends resulting in a more round opening. To determine the exact spacing you would draw a circle the size of the duct, divide the circle a number of times and project that across to a side view.

[Sengna]

That is called a transition piece (rectangle to round) development.

 

Search for on the terms "developments" and "transition".

A search should turn up many examples

 

[ATTACH]48583[/ATTACH]

 

Here is the layout of a general solution.

Thank JD Mather, very good info for me, i will spend more time pracetice from the tutorial.

[gazza_au]

Speak to the guys who will be pressing it up, they will let you know how many press lines they need.

[gazza_au]

As a fabricator we have programs to do this to save time..

Good luck

 

 

 

[Sengna]

As such you can just fake it and the fewer the lines the better, just enough to get the point across. The lines represent the bend lines that would be required to actually form the piece with more bends resulting in a more round opening. .

I like that. Fake it until you make it LOl. Thanks rkent for showing me, very easy to follow. I was wonding what type of tool they use to bend this sheet metal in the shop.

[Dana W]

The tool is called a Brake. An overhead blade (blunt) will press the flat sheet down while the hinged edge of the tool table is driven up, either hydraulically, or with a hand lever to bend the metal the required amount.

[ROBP]

As a drafter i have a lisp already posted in cadtutor forum last month.

 

i did a quick test with the lisp see attached results.

 

Best,

Rob

[Sengna]

As a fabricator we have programs to do this to save time..

Good luck

 

 

 

[ATTACH=CONFIG]48593[/ATTACH][ATTACH=CONFIG]48594[/ATTACH][ATTACH=CONFIG]48595[/ATTACH]

That makes your life much easier it n't it gazza_au

[gazza_au]

Yes Sengna it certainly does.. most of my stuff is laser,plasma or water cut so it's easy to just send them a dxf, let me know if you need a development done so you can compare it to your new skills :-)

[mdbdesign]

As a drafter i have a lisp already posted in cadtutor forum last month.

 

i did a quick test with the lisp see attached results.

 

Best,

Rob

Rob, can you attach link to program you posted? Can't find it.

Thank you.

[ReMark]

Could it be the one contained in this thread?

 

http://www.cadtutor.net/forum/showthread.php?83641-Modifying-an-existing-lisp-to-generate-multiple-flatten-cones-ant-the-same-time

[mdbdesign]

Could it be the one contained in this thread?

 

http://www.cadtutor.net/forum/showthread.php?83641-Modifying-an-existing-lisp-to-generate-multiple-flatten-cones-ant-the-same-time

 

 

Thanks ReMArk.

[ROBP]

Could it be the one contained in this thread?

 

http://www.cadtutor.net/forum/showthread.php?83641-Modifying-an-existing-lisp-to-generate-multiple-flatten-cones-ant-the-same-time

 

Nop mark that aint the one Mdb is referring to ,the one he needs is the one sent after the conedev remember the one where you had to change the location with the backslash pointing towards the bottom right to upper left?

 

R

[mdbdesign]

Nop mark that aint the one Mdb is referring to ,the one he needs is the one sent after the conedev remember the one where you had to change the location with the backslash pointing towards the bottom right to upper left?

 

R

Now I am confused, ROB can you post complete file (lsp)?

[ROBP]

Marek i will get **** from the forum delty's if i post it wrong seen it over and over again lately they always think since they know the inside out and every corner of the rooms that does exactly mean others do, and the lisp is in 2 parts with multiple slides i would not know where to begin and if a do it wrong i get the **** for it.

 

Must there be another way to do it?

 

Best

R

[ROBP]

That is called a transition piece (rectangle to round) development.

 

Search for on the terms "developments" and "transition".

A search should turn up many examples

 

[ATTACH]48583[/ATTACH]

 

Here is the layout of a general solution.

 

Note that the correct solution is an arc length, then flattened out.

You would take these from the top view as they are not true length in the view you have shown.

 

Of course, with modern 21st century CAD tools, you simply model the finished part and the CAD tool gives you the Flat Pattern development.

An in-depth analysis would show that the classical method is a "fudge" anyhow.

 

Flat pattern dev please link the tutorial JD because so far and over all the years searching i was not able to achieve easily the flattening part option on my side with cad, although the sleeve is big enough and plenty of room in it to put in unfortunately i was never able to find it and put it up in it.

 

R

[Cad64]

Must there be another way to do it?

 

Yes, just post the .lsp file here. No need to go digging around trying to find some old thread. If you have the working lisp routine on your computer, just attach it to your next post.

[ROBP]

Yes, just post the .lsp file here. No need to go digging around trying to find some old thread. If you have the working lisp routine on your computer, just attach it to your next post.

 

No # in front and the end etc etc never did post lisp live and do know how anyway therefore i prefer to attach zip file and avoid criticism.

 

Please remember if you ever you modify it, send me a fresh copy. and the file must be located on your c drive or you must modify the exact path in the develop file end paragraph in the line (setq prgpath "C:/DEVELOP/")

ex: if the file develop is in c in a folder name new

(setq prgpath "C:/NEW/DEVELOP/")

Edited May 6, 2014 by ROBP