Author Topic: 3D CAD software  (Read 1573 times)

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narrowminded

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Re: 3D CAD software
« Reply #30 on: November 13, 2018, 11:31:27 PM »
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OK, I'm finding some limitations of shetckup. The smallest rivet it will let you draw is 1mm in diameter. I even tried to scale it down with the scaling tool, and when it gets smaller than 1mm, it disappears.

And I was one to advise the simplicity side without ever having used Sketchup, as an example. :facepalm:  I may have overstated the simplicity side but the basic point I was intending to make was to keep it simple.  The cost of a viable program for occasional modelling use shouldn't be too awful expensive.  Or am I dating myself? :| ;)
Mark G.

Iain

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Re: 3D CAD software
« Reply #31 on: November 14, 2018, 01:02:33 AM »
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I like bricscad.  It does the job, and works on Linux.
Thanks much,
Mairi Dulaney, RHCE
Member, Free Software Foundation and Norfolk Southern Historical Society

http://jdulaney.com

peteski

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Re: 3D CAD software
« Reply #32 on: November 14, 2018, 01:10:59 AM »
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OK, I'm finding some limitations of shetckup. The smallest rivet it will let you draw is 1mm in diameter. I even tried to scale it down with the scaling tool, and when it gets smaller than 1mm, it disappears. One thing I could do is draw, in this case, a caboose, draw it 4 times larger than actual size, and then scale it down in the slicing program.
  I like that John (@Lemostream) made reference to the different styles of CAD, but I'm having trouble figuring out how to tell which ones are parametric and the ones that are not. As I said before, I do have a license for educational solidworks, but I could never get it to download (I have slow and unstable internet connection living out here in the in the sticks) and installed on my computer. I have sent a email to them to see if I can purchase the software on a CD.
 I guess for now, I'm just going to stick with sketchup and only draw within it's capabilities.

I just tried SketchUp 8 (the latest I have installed) and drew a 1mm circle. Then I scaled it to 0.2mm and was able to push it out by 0.2mm to make it a cylinder.
When I created a blank drawing I used Product Design and Woodworking template (seemed most appropriate).
« Last Edit: November 14, 2018, 01:12:42 AM by peteski »
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rodsup9000

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Re: 3D CAD software
« Reply #33 on: November 14, 2018, 03:13:02 PM »
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I just tried SketchUp 8 (the latest I have installed) and drew a 1mm circle. Then I scaled it to 0.2mm and was able to push it out by 0.2mm to make it a cylinder.
When I created a blank drawing I used Product Design and Woodworking template (seemed most appropriate).

 Pete, using the same template as you. I was playing around again this afternoon and got the rivet down to .4mm diameter. So, I think I can work with that.
Rodney

My Feather River Canyon in N-scale
http://www.therailwire.net/forum/index.php?topic=31585.0

peteski

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Re: 3D CAD software
« Reply #34 on: November 14, 2018, 03:53:41 PM »
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Pete, using the same template as you. I was playing around again this afternoon and got the rivet down to .4mm diameter. So, I think I can work with that.

When designing small models (N scale) I ran into problems using the "follow me" function to chamfer edges.  I ended up drawing the model much larger (I think I even designed it in 1:10 scale, then scaled it down to 1:160.  I think this shortcoming was mentioned here in an earlier post.
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Chris333

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Re: 3D CAD software
« Reply #35 on: November 14, 2018, 04:02:40 PM »
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When designing small models (N scale) I ran into problems using the "follow me" function to chamfer edges.  I ended up drawing the model much larger (I think I even designed it in 1:10 scale, then scaled it down to 1:160.  I think this shortcoming was mentioned here in an earlier post.

I had to do the same thing trying to make steam loco domes. I couldn't get it to work over and over. Then I scaled it much bigger and it worked just fine.


So you guys are making rivets that aren't domed? I guess that small you couldn't tell.

rodsup9000

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Re: 3D CAD software
« Reply #36 on: November 14, 2018, 08:47:52 PM »
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So you guys are making rivets that aren't domed? I guess that small you couldn't tell.

 Here is my rivet



Rodney

My Feather River Canyon in N-scale
http://www.therailwire.net/forum/index.php?topic=31585.0

Lemosteam

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Re: 3D CAD software
« Reply #37 on: November 14, 2018, 09:04:08 PM »
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I had to do the same thing trying to make steam loco domes. I couldn't get it to work over and over. Then I scaled it much bigger and it worked just fine.


So you guys are making rivets that aren't domed? I guess that small you couldn't tell.

I model a sphere, replicate it to all the positions I need as a single body and bury them into the solid to get the diameter I want, but usually bury it halfway in, an then I join the body to the parent body for a result.

wcfn100

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Re: 3D CAD software
« Reply #38 on: November 14, 2018, 09:16:18 PM »
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So you guys are making rivets that aren't domed? I guess that small you couldn't tell.

Using cylinders is generally okay with the resolution of these machines. Also cylinders can keep the triangle count down in a file.  When I scaled up the Pullman "Dart End" file to O scale the first time, it was something crazy like 100MB because of the iterations of the rivet heads.

I try to design rivets with variables that I can adjust to different machines (generally that machines minimum detail).  I'll then use that variable for other minimums like making raised hood doors.

Jason

Lemosteam

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Re: 3D CAD software
« Reply #39 on: November 19, 2018, 11:07:13 AM »
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I doubt this, but if any of your software can generate a .jt file, I recommend obtaining the VisMockup product, I think there is a free version out there with limited capability, but it is fantastic as a viewer.  The free version (JT2GO) will only view .jt files, but there are paid versions as well that will import .stp, and .stl and others but I have no idea how much that version is.

.jt files are referred to as "light" cad data using surface data, where native CAD data is "heavy" using solid data to generate representations of the models.

-Dynamic cross sections through assemblies are indispensable for determining if your designs fit together properly and if there are any design clashes within the assembly.
-The ability to transform (move) parts can help with instructions and exploded views etc.

The following website has some demos and product info.
https://www.plm.automation.siemens.com/global/en/products/plm-components/jt.html

Just posting for those wishing to invest in their CAD skills further.

Lemosteam

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Re: 3D CAD software
« Reply #40 on: November 29, 2018, 08:20:06 AM »
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Copied from the Anycubic thread for posterity in this one.

"A shell is a 3D body.  Since you added four bodies together into one file, the bodies may be face to face or line to line in a section or even overlapping (see example below) but not JOINED into one body, so the system thinks there are still four separate parts.

Here are cad examples of the same design in section, two shells (bodies), and a single body after a boolean join operation in cad.  The two upper are in CAD and the two lower are .stp files show sectioned in my viewer.  The left pair would be interpreted as two shells and the right as one shell. take note of the white tessellation lines (read on) on the surfaces in each example:



If your CAD tool has boolean operations, you will need to create a body the runs through the joints and makes all if the bodies into a single body (as if you modeled it as a single body).  Think of it as the glue in the joints.

Translations (.stl, .igs, .stp, etc.) of CAD models are not perfect, particularly .stl files as .stl files use triangles to simulate the perfect solid.  Even on a square flat plane, .stl conversion could turn that into a minimum of two triangles or many.  This is known as Tessellation.  Also these types of translations ar known a "light" data because the translations use only the surfaces, not the solid ("heavy" CAD) to make it easier to load into a viewing tool.

This imperfection can lead to infinitesimal gaps between surfaces that LOOK like they intersect but in fact do not.

As a good practice, .stl files should not be modified, rather always work in the master CAD file from your CAD software and export a new .stl.  "File>Save As" is cheap if you don't want to disturb your original CAD file, to make a new CAD file for different printing needs.

Here are four examples of popular conversions of the same part in my viewer and the first image is in my CAD software.  I have turned on "edges" (black) and Tessellation lines (white) so you can see them, surfaces are grey.  Note the different interpretations by each conversion.  And to top it off, if you made a slight topographical change in any of the features, the tessellation might be completely different the next time."
 


All of this is one reason why some free CAD software is not optimal for true designing.  Some work in surface data only giving the impression you are designing a solid.  The tools have the ability to intersect these surface based extrusions (light data) to allow for the conversion tools to tessellate them properly to print.

Boolean operations are the only way to ensure the CAD is a true, filled volume (heavy data) and why some CAD tools are better at filleting than others.

Imagine loading the heavy data of an entire engine assembly or vehicle into your CAD tool- memory overload just from the engine assembly.

Now take all of those parts and convert them to light data and you can load them into a viewer, yes the entire vehicle.



rodsup9000

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Re: 3D CAD software
« Reply #41 on: December 02, 2018, 07:40:12 AM »
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"A shell is a 3D body.  Since you added four bodies together into one file, the bodies may be face to face or line to line in a section or even overlapping (see example below) but not JOINED into one body, so the system thinks there are still four separate parts.

Here are cad examples of the same design in section, two shells (bodies), and a single body after a boolean join operation in cad.  The two upper are in CAD and the two lower are .stp files show sectioned in my viewer.  The left pair would be interpreted as two shells and the right as one shell. take note of the white tessellation lines (read on) on the surfaces in each example:



If your CAD tool has boolean operations, you will need to create a body the runs through the joints and makes all if the bodies into a single body (as if you modeled it as a single body).  Think of it as the glue in the joints.

Translations (.stl, .igs, .stp, etc.) of CAD models are not perfect, particularly .stl files as .stl files use triangles to simulate the perfect solid.  Even on a square flat plane, .stl conversion could turn that into a minimum of two triangles or many.  This is known as Tessellation.  Also these types of translations ar known a "light" data because the translations use only the surfaces, not the solid ("heavy" CAD) to make it easier to load into a viewing tool.

This imperfection can lead to infinitesimal gaps between surfaces that LOOK like they intersect but in fact do not.

As a good practice, .stl files should not be modified, rather always work in the master CAD file from your CAD software and export a new .stl.  "File>Save As" is cheap if you don't want to disturb your original CAD file, to make a new CAD file for different printing needs.

Here are four examples of popular conversions of the same part in my viewer and the first image is in my CAD software.  I have turned on "edges" (black) and Tessellation lines (white) so you can see them, surfaces are grey.  Note the different interpretations by each conversion.  And to top it off, if you made a slight topographical change in any of the features, the tessellation might be completely different the next time."
 
All of this is one reason why some free CAD software is not optimal for true designing.  Some work in surface data only giving the impression you are designing a solid.  The tools have the ability to intersect these surface based extrusions (light data) to allow for the conversion tools to tessellate them properly to print.

Boolean operations are the only way to ensure the CAD is a true, filled volume (heavy data) and why some CAD tools are better at filleting than others.

Imagine loading the heavy data of an entire engine assembly or vehicle into your CAD tool- memory overload just from the engine assembly.

Now take all of those parts and convert them to light data and you can load them into a viewer, yes the entire vehicle.




  OK, John, I think I understand some of what your saying. Lets say I have a object like what @Chris333 had problems with, and export it as a 3ds file. Is a 3ds file a better file???? I know at times when I export a stl file of a object that I've drawn in Sketchup, it has to be repaired for some reason or another, before it can be printed. I take that same object and export it as 3DS file, then import into netfabb (or some other software for 3d printing) and the software says it's a good file that needs no repair. Then I can take that 3DS file, and export it as a stl file and it will print correctly. 
I should of tried it with Chris's ore car to see if a 3ds file would of fixed it.
Wish that Photon slicer would take 3ds files, but it'll only take stl's and photon stl's.



Rodney

My Feather River Canyon in N-scale
http://www.therailwire.net/forum/index.php?topic=31585.0

Lemosteam

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Re: 3D CAD software
« Reply #42 on: December 02, 2018, 11:28:45 AM »
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@rodsup9000

This is why you need a real CAD tool.  I think some of these software out there do not create solids. 

Are there any settings in sketchup that let you increase the accuracy of the stl file?

Looking online, it appears that a 3ds file is one that simulates an autodesk format, which may be a true 3D solid CAD file that this Netfab can read as a true 3D file.

I think you may have stumbled upon a good workaround for the issue.  Since Netfab is interpreting the file better, the resulting stl file must be more "accurate"/clean than an stl file directly from sketchup, or so it seems.

Remember the discussion about light and heavy data?  I don't think slicers can use heavy data (too much calculation beacus of a solid) and .stl is the industry standard format.

Again, it might be worth it to get a true CAD software that can export proper stl files. 

wcfn100

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Re: 3D CAD software
« Reply #43 on: December 02, 2018, 11:50:49 AM »
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@rodsup9000

Looking online, it appears that a 3ds file is one that simulates an autodesk format, which may be a true 3D solid CAD file that this Netfab can read as a true 3D file.


3ds is a native Autodesk format going back to at least 1996 with the release of 3D Studio Max.

Jason

rodsup9000

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Re: 3D CAD software
« Reply #44 on: December 02, 2018, 12:49:52 PM »
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@rodsup9000

This is why you need a real CAD tool.  I think some of these software out there do not create solids. 

 As I'm drawing with sketchup, I've learned how to keep objects solid, so I don't have any holes. Sometimes I just have to draw a line to make a part solid, and then delete the line and it stays solid.

 I guess I need to get solidworks loaded, now that I have a install disk now. I know it's going to be very hard for me to unlearn everything I learned from using sketchup for the last 7 years of using it.



@rodsup9000


Are there any settings in sketchup that let you increase the accuracy of the stl file?

Looking online, it appears that a 3ds file is one that simulates an autodesk format, which may be a true 3D solid CAD file that this Netfab can read as a true 3D file.

I think you may have stumbled upon a good workaround for the issue.  Since Netfab is interpreting the file better, the resulting stl file must be more "accurate"/clean than an stl file directly from sketchup, or so it seems.

Remember the discussion about light and heavy data?  I don't think slicers can use heavy data (too much calculation beacus of a solid) and .stl is the industry standard format.

From what I've learned, yes third party software converts stl files better than sketchup. Most of the stuff I draw up in sketchup converts OK with no problems at all, but heavy data files will leave some holes and in some cases, can't be repaired by third party software, like Chris's ore car.

 Mike, my retired architect/architectural model builder friend, drew the keystone and the scrolls (I guess that what they are called) up in autocad and the rest was done in sketchup. He imported the autocad stuff as 3ds files and added it to the sketchup drawing. He says that some stuff is easier for him to do in sketchup than autocad. He sent me the exported stl file from sketchup and I could see it was full of holes and the keystone wasn't even there when I loaded into any slicing programs. Then he sent me the exported 3ds file and I used netfabb (it showed up as a whole object) to convert it to the stl file for printing.








 And thanks again for explaining how CAD works. It helped me and others, I'm sure.
« Last Edit: December 02, 2018, 12:57:12 PM by rodsup9000 »
Rodney

My Feather River Canyon in N-scale
http://www.therailwire.net/forum/index.php?topic=31585.0