Working with a sloped top chassis

Jim Canale

I have some questions that are hard for me to communicate.  Probably because I never did much manual drafting. 

I'm designing a test fixture in a sloped top chassis.   Various items must mount in cutouts in the sloped top, and also in the front and rear surfaces.   I have to verify there is sufficient clearance between the components for cabling, air flow, etc.   The machinist is going to fixture each mounting surface level to his machine table to cut the mounting holes for same surface.   Since the top of the chassis is sloped, the GENERATE VIEWS" tool will create a shortened view of the top surface.   So I have to generate a supplemental 2D view that accurately locates and sizes the holes in the top.    

If I had 3D models of ALL my components, I could mount them in the 3D chassis, then generate 2D views, and measure the clearances on the 2D views.  However, some of the components are very complex and the vendors only provide 2D models.  That is problem number one.

Problem two is generation of that supplemental view of the top surface.   Years ago, when I designed in 2D, I knew how to do this.  But I have forgotten.   I don't think the isometric view provides what I need, does it?

Maybe my approach to this is all wrong.  

Can someone take me through this?

John Gaunt

If I understand the issue properly (maybe I don't), you draw a true plan projected from the ramp face on the angle.
In 2d on the computer I copy the foreshortened plan and turn it so you can project holes etc from 'side on' to the true plan.
So you locate things from an X and a Y direction square to the true plan.
For views through population on the ramp at odd angles, I think you do a similar thing starting from that true plan.

Jason Bourhill

You want to create an auxiliary view? As far as I can see this isn't possible with VIEWBASE. However you can create a SECTIONPLANE and use then use SECTIONPLANETOBLOCK to create your 2d view.

Attach and example drawing to illustrate

Assuming this is what your looking for, then you might also like to look at BIMSECTION. This is inherently more flexible than VIEWBASE

Regards,

Jason Bourhill

CAD Concepts

AuxViews.dwg

Roy Klein Gebbinck

Another option is using the FlatShot command.
1.
In a 2D Top view first use the FlatShot command to create a block that can be selected for replacement in one of the next steps.
2.
Align the UCS with the sloped face and use the Plan command to align the view.
3.
Again use the FlatShot command and replace the block from step #1.

Note that a FlatShot block does not automatically update if the model changes.

Hans De Backer

As far as I understand, the VIEWSECTION command is what you are looking for.
First use the VIEWBASE command to generate base views of the chassis, among which a view that looks sideways onto the sloping face, so the face is depicted as a sloping line.
Next, start the VIEWSECTION command, select the sideways view, and define the section line by snapping to the start and end of the sloping line: a not-shortened view of the sloping face will be produced.
Now, it is better to move the section line a bit away from the sloping face to avoid any calculation errors that may occur when a section plane coincides with one of the faces in your model.

Jim Canale

@John Gaunt:

If I understand the issue properly (maybe I don't), you draw a true plan projected from the ramp face on the angle.
In 2d on the computer I copy the foreshortened plan and turn it so you can project holes etc from 'side on' to the true plan. ....

Yes I think you have sized the problem up John, but it is not that easy.  What angle do I make the auxiliary view, relative to the other views?  How do I easily generate a true view of the sloped top (normal to the top).

Jim Canale

Jason,

Thanks.  You seem to have accomplished what I want, but I don't understand how you got it.  Let me play with your technique a bit, and I will get back to you.

Jim C.

Jim Canale

Hans,

Is this what you are talking about?  Or did I do something wrong.   The angle doesn't look right to me..   And I couldn't dimension it (locate the holes relative to a corner) while in paper space.   I know I can export the views to model space, but then this just confirms what I have been telling Bricsys for months.  Namely, that the paper space 2D views are not ready for prime time.   

Experiment w Views.dwg

Jim Canale

Roy,
Thanks for your suggestion.  I haven't figured it out yet.  Give me some time.  This old codger is slow to learn.

Jim C.

Damian Harkin

The Experiment drawing shows hatching because the ViewSection was defined right on the sloping surface.  BricsCAD is cutting through the material.  If you make an offset line up from the surface and use that do define the section, you will get the correct view.

Hans De Backer

Jim,

yes, that is what I meant. Concerning the angle: the VIEWSECTION result is forced to remain orthogonal to the section line, this is as per AutoCAD design...
I mentioned the VIEWSECTION possibility assuming you were looking for a solution in the VIEWBASE realm.

If you prefer complete freedom you probably will prefer using SectionPlanes instead, as suggested by Jason.

Joe Dunfee

Before I comment, I want to say that it is quite possible that I mis-understood the original need. Especially since I  don't use a lot of the command to create some of these types of views.

Why not simply create a custom UCS that you create coincident with the sloped face.  Then, use a plan view for that UCS?  You can also save a view of that face.

The actual view that shows the view of the sloped face does not necessarily need to be positioned like an auxiliary view.  Simply put arrows showing where the view is looking, like you might for a section view.

-Joe

Patrik Sparrman

Hi, tried to interprete what your problem is. Maybe you can trace the countour of the 2d pieces and extrude them to make your cutout. Then you can use the above views to generate your drawing.  See attached file. ( turn it to top view and then rotate to see what I mean) Im guessing half the probllem is getting a view in the plane. The main problem is what to cut out.

section.dwg

Jim Canale

Thanks all!  I have lots of things to try.   And thanks for your patience.    Everything comes hard to me.   Partly  because I'm old and it probably doesn't help that I grew up with Dyslexia.  When others see a picture of a cube, I see the corner of a wall.  For years letters like E's pointed to the left, rather than the right!   I also never had a course in drafting, and I get confused about the terminology.  Perhaps I shouldn't be doing CAD work, but I find it enjoyable.

I made a duplicate of the 3D model, rotated it so the angled surface was parallel to my current coordinate system, then used GENERATE VIEWS tool to make the auxiliary view.   But that view was orthogonal, and I'm told an auxiliary view of an angled surface should be projected at the same angle.   I wasn't able to rotate the view in paper space, so I exported to model space and then rotated.   All that may be equivalent to what Joe suggested.  However, I've never been clear on what a "Plan" view is, or for that matter, the difference between WCS and UCS.

I still need a quick way to check clearances between components inserted from the back wall, and components inserted into the sloped top.  If I had 3D models of all my components (very time consuming to make), I could insert them into the 3D chassis, group the bunch, and rotate the thing around to see if there are any clearance problems.  But most of my component models are 2D.

Attached...  picture I fond online showing how auxiliary views are supposed to be presented on a 2D drawing.



 

AuxViews.dwg

Jim Canale

Ooops.  Posted wrong file...  Here is the picture I found.

Auxiliary View.jpg

Jason Bourhill

@Jim Canale:

I still need a quick way to check clearances between components inserted from the back wall, and components inserted into the sloped top.  If I had 3D models of all my components (very time consuming to make), I could insert them into the 3D chassis, group the bunch, and rotate the thing around to see if there are any clearance problems.  But most of my component models are 2D.

If you're not interested in producing a drawing as an end result, then perhaps try approaching this problem from the opposite direction. You could instead copy your 2D components to overlay them on the 3D face you want to check. If these 2D components are blocks, then when you INSERT them you can take advantage of DUCS to automatically align the inserted component two your face. If your components aren't blocks, then you could use the Copy / Move DUCS utility I posted here

https://forum.bricsys.com/discussion/28839
The included animated gif illustrates what I'm talking about.

Regards,

Jason Bourhill CAD Concepts

Patrik Sparrman

Jim Jason and I are both aiming in the same direction but the question is what is the projection of the 2d items (blocks or whatever). Do you get a projection in the sloped plane or is it x/y projections. Look at my file from all angles ( maybe i slanted the plane a bit much ).  /Patrik

Patrik Sparrman

File also

section.dwg

Jim Canale

Jason & Patrick,

Thanks again for your inputs.   I'm clear on the creation of the auxiliary view. 

It gets down to placing my components in the right place, so there are no clearance issues.  As I said before, if I had 3D models of my components, I could insert them where I wanted, and use REAL TIME MOTION to quickly look for any interferences.   (Very sImple example attached.)  

My issue is I have to place a dozen complex components into the box from the back and front sides, as well as through the sloped top.   A box with very little space to spare.   There are bound to be some collisions.    I think I am going to have to either commit to making the complicated 3D models or superimposing the 2D component views on the appropriate chassis views, and using infinite rays to check for interferences. 

Jim C.

Joe Dunfee

 The 3D models of the parts don't have to be complex.  Perhaps you simply take a top, front and side view of the part, and extrude both, then boolean interfere them.  It won't look pretty, but it will indicate the space it needs.  

I have even created 3D models using an image of a drawing from a web site. I pasted the image into BricsCAD, scaled the image and traced over the outline of the part.  Since the image was a generic one of a family of products, I had to stretch parts of the  drawing to agree with the dimensions from their catalog.  If you have any doubt about parts of the drawing, be generous with the dimensions, to make sure it will fit.

Of course if you want to be very certain everything will fit before you make the chassis, you should obtain the actual parts, then test fit them into a mock up of the chassis.  You create this mock up by printing the flat pattern onto paper.  If you don't have a large enough printer, print to a PDF.  Then, use the ability of Adobe's PDF viewer to automatically tile the larger drawing onto smaller sheets.  When you have your print out, tape or glue the paper to cardboard, and cut it out.

In spite of the benefits of the real-time rendering of 3D images, a real world model is still better, and gives a better feel for the final product. If you are an experienced designer, you probably have a good feel for what works in terms of clearances and need for air circulation.  The physical  model may help with that.

-Joe

Patrik Sparrman

Spot on Joe previously  I only extruded in one dimension. Now I have extruded front and side but my plane looks strange as it is at a very sharp angle.

Patrik Sparrman

Aahh file also

section.dwg

Joe Dunfee

 Patrick, when I attempt to open the file in your last post, the BricsCAD server says it can't find the file. There is a problem with the BricsCAD server. 

-Joe

Patrik Sparrman

adding it again

section(3).dwg

Jim Canale

Joe,

Yeah, you're right.  I'm going to have to put in the work, and make approximations of the 3D models.    I don't like resorting to multiple 2D views to check for interferences.    In fact, I think the quality of 2D models I get from vendors these days has suffered.    Probably because they are derived from 3D models, rather than created from scratch.

I'd like to thank you and all the others for helping me with this....   I'm out of here to finish some hot jobs..

Incidentally, in my last post, I had intended to attach a very simplified drawing of what I am dealing with.... I forgot to post it... So I have now.

Simplified Housing w 3 Components(2).dwg

Joe Dunfee

 None of the attachments on any of the forum threads are working.  You are taken to a page that says, "Oops. We didn't find what you are looking for"

-Joe