Author Topic: Google Sketchup help  (Read 1043 times)

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PiperguyUMD

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Google Sketchup help
« on: April 09, 2014, 03:11:27 PM »
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OK I'm not sure where to post this, but since this is an n scale project and many of you are involved in 3D printing projects so I figured I would start here.  I'm working on an A-B set of Baby-faced Baldwins for an individual in Maryland, and the first 3/4 of the project where a snap.  Now I'm to the cab and nose on the A unit and I've hit a rock wall.  I'm pretty good with sketch up and have done several commissions, including some steam locomotives.  I cannot for the life of me figure out how to do all of those curves!  Does anyone have any suggestions?  Are there some magical plug-ins that I don't know about?  What software are some of you using and how does it handle complex curved faces?  Thanks for the help!

bbussey

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Re: Google Sketchup help
« Reply #1 on: April 09, 2014, 06:12:01 PM »
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I'm not familiar with Sketchup.  But in SolidWorks, you would use a sweep emboss with a number of sketches as guidelines for the sweep.  Diesel noses are not easy.  Nor are the tail end of observation car roofs.  If you could find sectional engineering drawings of the carbody, it would be easier as you would base your guidelines and cross-sections sketches on that.
Bryan Busséy
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3rdboxcar

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Re: Google Sketchup help
« Reply #2 on: April 10, 2014, 06:38:34 AM »
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I assume you are using the free version and not the pro version

How I do it with the free version -

Create the 2 arcs
Join them at one end and use follow me
do the same for the next curved surfaces, it will then look like a dogs breakfast,
select all and Intersect faces
then the fun bit - delete all unwanted geometry

PiperguyUMD

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Re: Google Sketchup help
« Reply #3 on: April 10, 2014, 08:57:23 AM »
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I assume you are using the free version and not the pro version

How I do it with the free version -

Create the 2 arcs
Join them at one end and use follow me
do the same for the next curved surfaces, it will then look like a dogs breakfast,
select all and Intersect faces
then the fun bit - delete all unwanted geometry

That's right, I'm using the free version, but I'm looking to purchase software over the summer.  Is this process any easier in the pro version?

Shipsure

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Re: Google Sketchup help
« Reply #4 on: April 10, 2014, 10:09:36 AM »
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Those noses are really tough.  We spent a few weeks getting the FT and F7 noses right with some pretty expensive software...and it still required some hand work on the tooling to smooth things out.  It may be a case where you have to do some sanding on the finished project to get the contour you want. 

Joe

3rdboxcar

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Re: Google Sketchup help
« Reply #5 on: April 10, 2014, 12:34:31 PM »
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That's right, I'm using the free version, but I'm looking to purchase software over the summer.  Is this process any easier in the pro version?

It should be, when you pull surfaces through another shape etc. you end up with 2 solids which are easily split, subtracted, trimmed, in the free version you have to delete every line individually. And as far as I know that is the only benefit the paid version can do for us modellers. What it won't do is make it any easier to get the curve right.
When I did the Electroliner it took the age of a crow to get it right mainly for two reasons, I could not just go and measure and check and I had numerous curved surfaces coming together. I ended up putting in some curved sections manually with triangles as required.
Try and think what the framing under the skin looks like since that is how the real thing was built - may help.

Trying to do a Rock Island 2500 series Capone car roof at the moment !!***

If as bbussey says you could have a series of cross sections it would be easy, or If you had a series of reference points you could use the sand box.

GimpLizard

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Re: Google Sketchup help
« Reply #6 on: April 11, 2014, 08:01:42 AM »
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I think KeyCreator could do it, using splines. But it would still take some time. Looks like I'd have to create multiple bodies, and then boolean-join them all together, at the end.

Shipsure

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Re: Google Sketchup help
« Reply #7 on: April 11, 2014, 10:18:13 AM »
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I'm surprised no one has used a scanner on some HO models to get a few nose options available to use  :D

GimpLizard

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Re: Google Sketchup help
« Reply #8 on: April 11, 2014, 01:11:54 PM »
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The problem with scans is that the resuting files are STL. Not getting too technical here, but rather than lines and arcs, the bodies are defined by a whole bunch of tiny triangle slivers. And if you zoom in real close you will see that curved surfaces are not really smooth. STL are not true CAD files. They're the format that 3D printers use. They can be opened in CAD, but you can't do much with them after that. And they are hard (if not impossible) to convert to a true CAD format. I currently don't know of any program that will convert an STL to a editable 3D CAD format, such as IGES or STEP. (If anyone out there does, I'd sure like to hear about it. It's something that is long over due.)
« Last Edit: April 11, 2014, 01:13:58 PM by GimpLizard »

haasmarc

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Re: Google Sketchup help
« Reply #9 on: April 11, 2014, 04:15:11 PM »
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I hope you are going to make them available on Shapeways.  I have been wanting CNJ baby faces for a long time.  Once you figure out the nose, you could do the double ender.
Marc Haas
Keeping the Reading alive in N scale!

3rdboxcar

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Re: Google Sketchup help
« Reply #10 on: April 11, 2014, 05:12:55 PM »
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I think KeyCreator could do it, using splines. But it would still take some time. Looks like I'd have to create multiple bodies, and then boolean-join them all together, at the end.

Basically that is how I do any strange curved surfaces in Sketchup, about 3 hours to do the roof ends on the Capone cars.

PiperguyUMD

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Re: Google Sketchup help
« Reply #11 on: April 11, 2014, 06:42:48 PM »
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I hope you are going to make them available on Shapeways.  I have been wanting CNJ baby faces for a long time.  Once you figure out the nose, you could do the double ender.

Thats part of the agreement I have with the commissioner.  The B unit is viewable in my shop, but I'm plodding away on the A unit!

bbussey

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Re: Google Sketchup help
« Reply #12 on: April 11, 2014, 06:53:32 PM »
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The problem with scans is that the resuting files are STL. Not getting too technical here, but rather than lines and arcs, the bodies are defined by a whole bunch of tiny triangle slivers. And if you zoom in real close you will see that curved surfaces are not really smooth. STL are not true CAD files. They're the format that 3D printers use. They can be opened in CAD, but you can't do much with them after that. And they are hard (if not impossible) to convert to a true CAD format. I currently don't know of any program that will convert an STL to a editable 3D CAD format, such as IGES or STEP. (If anyone out there does, I'd sure like to hear about it. It's something that is long over due.)

First off, you can use the imported STL files from which to trace the arcs and/or splines you need in order to render the complex curves.

Second — unless you're going to convert your digital 3D model into G-code for CNC milling purposes, it's academic because you must convert your file into an STL format for rendering RP parts and it's not as if the triangles are large enough to see even under magnification.
Bryan Busséy
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