Corrugated iron

Tom Foster

Can I generate a sine wave and extrude it, as classic 'corrugated iron', either as a surface or as a solid 0.7mm thick?

Louis_Verdonck

Dear Tom

The Entity option of the PolySolid command allows to extrude linear entities to solids, while the Surface mode of  the dmExtrude command extrudes linear entities as a surface.

Tom Foster

Yes but can I generate a sine wave (2D linear entity)?

Roy Klein Gebbinck

if a sine wave approximation is OK:
Fillet a zigzag polyline.
Or if you want more dimensional control:
Draw circles for the top and the bottom part, draw a line tan/tan to the circles, mirror, trim, array or copy, join.

Tom Foster

Thanks Roy, I can do that kind of thing, just wondered if there was some programatic way - should be economical.

Alan Liddle

@Tom Foster:

Can I generate a sine wave and extrude it, as classic 'corrugated iron', either as a surface or as a solid 0.7mm thick?

It is a "once only" venture so just hack it for a fast result. I did it a while back and just copying sheets  from the original one.

Tom Foster

Just to check once more - there is no function in Brics to create a 2D curve by a mathematical formula? I ask because there is such a facility in Microstation.

Hans De Backer

There are lisp utilities that allow to draw sinusoidal curves, like this free one created by Tony Hotchkiss
http://cadtips.cadalyst.com/curved-objects/sinusoidal-curve

After downloading and unzipping the file in e.g. your BricsCAD support folder (which you can easily identify by typing SUPPORTFOLDER on the command line),
make sure to rename the two files so the undesirable '0305alspsol-' prefix is removed, so the names become sinecurve.lsp and sinecurve.dcl.

To use the tool, the lisp code should be loaded. There are many ways to do that, an easy one is: from Windows Explorer, drag sinecurve.lsp and drop it somewhere on the BricsCAD window. Once successfully loaded, a prompt will be printed: "Enter SC to start"... so next you type the 'SC' command and can start setting parameters and creating curves.

Mind that lisp programs should be loaded per drawing, so when switching to another drawing, SC will not be available until you load it also for that drawing. If interested, there are ways to automate this.

Richard Webb

 Or...

Just use the HELIX command. Rotate the helix 90-deg about Y to put the helix axis along X. FLATTEN to put it at Z=0. Done. The rest is the usual offset, region, etc. and there's the roof section.

sine_extr.jpg

Scott McKenzie

A few years ago, I splined a polyline, offset it the material thickness, capped the ends and then extruded it into sheets creating 4'x 12' sheets of tin siding for a building, it worked, and looked great but it was a huge drag on the cad file...  If I was to do it again, I would use thin rectangles and apply a hatch, section views or views showing the end of the sheet I would take the extruded polyline and use it as a block to detail the section.

Roy Klein Gebbinck

@ Richard: That is a very clever solution. I like it.

Tom Foster

Top prize on this occasion goes to Richard Webb - one day I'll play with DIY programatics like Hans offers.

To help me shortcut this learning, should I keep this piece of 'corrugated iron' as a Surface, or dmThicken it by 0.7mm into a Solid? Neither adds massively to file size.

As a Solid, it seems I must manufacture a large-area piece of corrugated iron, orient it and Slice it to final shape - no scope for readjustment widthwise, as a normal cuboid soild would via PushPull, Extrude etc - only lengthwise, and my graphics card doesn't like it.

As a Surface, what are the relevant tools, to do similar to Slice, PushPull, Extrude etc?

Tom Foster

After much messing, I have a corrugated sheet 3'-3" wide x 23'-3" long (standard cover size) created from a sine curve 3" wavelength x 3/8" amplitude (i.e. 3/4" section height) x 0.7mm thick (that's how it's dimensioned).

dmExtruding the curve to a Surface gives 65KB.
Then dmThickening that by 0.7mm to a Solid gives 119KB.

Instead Offsetting the 2D curve by 0.7mm then dmExtruding the boundary/shape to Solid gives 1.15MB.

Thought you'd like to know!

Tom Foster

Here is the result, attached. However it's added 1.5MB to the file, big delays whenever Selected. So should this be Xref'd in?

Something annoying - the green timbers below show through, spoiling the effect, even though the corrugated Surface has been artificially raised 1mm vertically (.842 perp) out of contact with them. Is this normal?

CorrugDormers.dwg

Dennis Fogg

I've had exactly the same "color bleed through" problem with thin solids. I haven't found a way to eliminate it either. The bleed through shows in a print preview too.

Jason Bourhill

@Richard Webb:

 Or...

Just use the HELIX command. Rotate the helix 90-deg about Y to put the helix axis along X. FLATTEN to put it at Z=0. Done. The rest is the usual offset, region, etc. and there's the roof section.

You're world famous!! Well to the few that watch you are:
https://bricsys.tv/m/?project-geometry---corrugate-iron-m243

I used PROJECTGEOMETRY to put a twist on your method. As Roy said, your method is a very clever solution.

Regards,

Jason Bourhill

CAD Concepts

Richard Webb

 Thanks! (even the terrible pun) And a good reminder to visit BricsysTV more often. One tends to get in a rut using the same old methods; I don't think I've tried surface extrude or project up to now. So many tools, so little time...