How to fold a plane around a curved surface?

MichelC · 14 Mar 2012, 22:51

Hello all, although not strictly a woodworking issues, I post my question here because this subforum has a few experienced SU users. I ran into a problem with folding a plane containing a set of windows around the front of a dodger, for the non-sailors: a doghouse over the front end of a sailboat cockpit. See the picture and you know what I mean.

In the background you see the flattened dodger that I used to draw the windows on. Drawing the windows right on the front of the dodger was no way to go, I couldn't get them to line up right. The windows are not rectangular, the vertical edges line up along perpendicular lines from the top to the bottom of the dodger front and the horizontal lines of the windows run along arcs parallel to the top edge of the dodger.

I tried the sandbox tool and TIG's superdrape but the sandbox doesn't really fold around the surface, it projects the plane vertically (down) on the surface. Superdrape wouldn't work for reasons I don't understand, it keeps telling me that group1 has to be above group2. I moved around the window-group1 to all directions upward but Superdrape wouldn't budge. I also tried Shape Bender but I can't get the lines (straight and curved) right.

Any way to get these windows down on the front of the dodger?

Dave R · 15 Mar 2012, 01:12

Michel,

Could you build a dodger for my Catalina 27?

So did you try turning the dodger face so it is "horizontal" for Super Drape? Maybe you said this and I didn't catch it. You might try Shape Bender to bend the flat version to match.

mac1 · 15 Mar 2012, 04:12

Look at the plugin tools on surface or just draw widow and then extrude thru dodger and intersect. You have a window plane intersecting with what looks like a truncated cone and the intersect should give the vertical sloped lines you want ?
You could also draw them with the line tool( make sure you use the correct inference). However from the pronounced arc at the their bottom I think you are using very high poly surface. Is it possible to post model at least the dodger portion?
Here is one concept using the line tool. Only one window drawn the rest made with radial copy. Not the lat line for ref.

TIG · 15 Mar 2012, 10:31

Try ExtrudeEdgesByVectorToObjects...

Dave R · 15 Mar 2012, 11:06

TIG, does that not result in a projection on the surface? That would be different from wrapping the flat windows around the dodger, no?

Tools on Surface could be good if you know where the lines need to go on the curved surface.

Shape Bender should allow you to take the flattened dodger surface with the glazing and wrap it back up. I would probably only work with the part of the dodger that has the glazing and not include the bit that wraps over the top.

On the other hand, I wonder if it wouldn't be easier to create a pleasing line by laying the glazing out on the curved surface. Seems it would be a bit like creating the proper sheer line. Much easier to get right on a 3D boat that on a flat drawing.

bjornkn · 15 Mar 2012, 11:08

I think I would've tried with Shape bender, with a slightly scaled curve (up or down). And then use Joint Push Pull to extrude those windows through the windshield/front wall. An Intersect-with-model would then stamp the windows nicely into the windshield?

TIG · 15 Mar 2012, 13:21

Yes it is a projection from EEbyVectorToObjects .
BUT how is anyone supposed to devise a 'flat' set of windows to wrap around a curved hull anyway ?
If you have an elevation [properly drawn] of these windows then you use those as the EEbyVectorToObjects edges it will project that truly onto the curved surface.
But how might someone otherwise decide on the form of the windows as a flat object that's floating in space that will somehow miraculously wrap onto an arbitrary surface to give the 'expected' result like any applied decal ?

mac1 · 15 Mar 2012, 14:15

TIG is on the money. It appears to me the confusion comes from the fact the OP presents the windows on developed surface which one gets when the surface of a cone is developed =>aka fattened. In actually one needs to ask the question how would this been done for an actual build or does one care?? The issue with the intersection I did not like when tried initially is the widows stiles will be warped because one is dealing with a double curved surface
Dave R. how would you actually build this??

Dave R · 15 Mar 2012, 17:33

Mac1, I'd pay the canvas guy up the road from the marina.

The frame would be set up on the boat first and then the fabric would be pinned up over it--much like fitting a suit on a dress dummy. The lines for the openings would then be marked out on the fabric while it is in place. Everything would be sewn on the flat but obviously tucks and darts would need to be put in the right locations to make the think fit.

mac1 · 15 Mar 2012, 20:20

Got It Dave. Like me when all else fails hire some one
Is he the same guy that makes the curved glass for you

Dave R · 15 Mar 2012, 21:20

Some things I could do but it would take me much longer so I figure it's better to pay a guy to just git 'er dun.

The glazing on the dodge is a flexible plastic--often vinyl so it corners to the shape just fine.

broomstick · 16 Mar 2012, 19:56

How to fold a plane on a curved surface?

Nothing more simple:

Forgive me.. I couldn't resist

Dave R · 16 Mar 2012, 20:04

MichelC · 18 Mar 2012, 17:17

@dave r said:

TIG, does that not result in a projection on the surface? That would be different from wrapping the flat windows around the dodger, no?

Tools on Surface could be good if you know where the lines need to go on the curved surface.

Shape Bender should allow you to take the flattened dodger surface with the glazing and wrap it back up. I would probably only work with the part of the dodger that has the glazing and not include the bit that wraps over the top.

On the other hand, I wonder if it wouldn't be easier to create a pleasing line by laying the glazing out on the curved surface. Seems it would be a bit like creating the proper sheer line. Much easier to get right on a 3D boat that on a flat drawing.

Dave, I tried laying out the windows on the dodger front but i couldn't get curved (horizontal) lines on the dodger front because the dodger front is not a neat arc. It's a mix of two arcs and two straight lines nearing the aft end of the sides of the dodger. I still haven't figured out how to do this. I'm now trying to place the windows separately in front of the surface and then push/pull them through the dodger surface and then intersect. See what happens.

Michel

mac1 · 18 Mar 2012, 18:09

It would help greatly if you posted your model or portions thereof so we know what you are really trying to do. Otherwise it is a guessing game