Workflow

russell_tucker

Hello guys,

I am new to Onshape and solid modeling but I have used Autocad for 2D drafting for many years. When I first started with Onshape, I decided to model a pin that has a knurl on a couple of cylindrical faces, but Onshape has a very hard time loading this knurl on my screen. Support explained to me why it was so taking so long to load, and explained to me that in normal modeling workflow the knurl would normally be called out on the drawing but not actually modeled, to keep file sizes and load times down.

This got me thinking, what else is standard knowledge for a solid modeler that I as a beginner may not know? And as a beginner where can I go online, or what books can I read, that will help me with proper workflow procedures that will let me create nice models without excess commands or operations that aren't needed?

I know a lot comes from experience, but there has to be something out there to get me started in the right direction.

Thanks for the help,
Russell

michael3424

Browsing the threads here, especially the problem solving type, can be helpful in learning appropriate techniques and gaining some sense of the workflow that the pros use.  Some of the other users go to a great deal of trouble to diagram and explain the approach they would use to accomplish a given goal.  The tutorials can also also help with this a bit.

3dcad

Use pattern where you can instead of repeating yourself.
Revolve is often powerfull replacement for multiple cutouts and fillets
Don't model the stuff you don't see in drawing (like threads) just add note for production
Remember that Onshape renders everything even if it's behind a cover or outside of viewport.

just to mention a few to keep things running smoothly.. but all this applies only when your model has a lot of stuff to process, it doesn't mean that 10 holes with threads in a plate would have any affect on performance

andrew_troup

Matt Lombard wrote some great books for Solidworks users at all levels, and many of the basic recommendations for best practice are either directly applicable to Onshape, or suggest concepts which will remain useful with contextual tweaks.

billy2

Russell this is probably the best place to hang and learn CAD. 3D parametric feature based CAD is still in it's infant stages and hopefully we'll be able to get some of the kinks worked out in the workflow. Different people want different things in a CAD system so you won't find consistency here or any where else. Me, I want to layout a design, create my parts and send it out for manufacture. I want to build 1st articles without any errors. Others want to document the design and control the processes which is more data intensive than what I want. 

You'll always need to manage what's on your screen and understand what's hard to render. All systems suffer from this and with time they will all get faster. It's more important to learn how to make things not show and then bring them back (hiding/unhiding). OS does a great job at this. Remember flat things render fast, curved things render slowly. Making all the curved things go away, yet still be able to design, is the perfect approach. In your case, patterning created a lot of features requiring many polygons. It's a polygon thing, keep the count low. Suppress the knurl and hide it. Bring it back when you want to make a print or impress someone with your modeling skills. Me, I don't try and make impressive models but I try to claim space. I focus on trying to insure 2 parts don't occupy the same space.

Geometry regeneration can hinder older systems which shouldn't be a problem here as everything always rebuilds and no subsequent rebuilds are needed. OS is the 1st here. It still rebuilds though. The intersection of 2 flat plates is easy to compute, the intersection of a cylinder and a flat plate is easy, the intersection of 2 curved surfaces is a nightmare for a solid modeler. Blocky stuff builds faster than curvy stuff. Keep your designs blocky. Unfortunately they'll be ugly. So it's a balance between cool & slow. I don't build ugly stuff, so I make a lot stuff go away when I'm designing to help performance.

When starting a design, think about the datums through the part/assembly you're working on. Having a proper structure from the part up to the assembly will allow you to build robust models and allow a multitude of changes downstream. This over all structure is the real difference between a rookie and a professional.

Good luck,

billy2

I agree with Andrew, Matt Lombard wrote a great book which I've thumbed through, Dave Pancoast from solidworks wrote some great training material, the Pro/E website has some very good material on advanced topics for parametric design and here at OnShape they put together some very good tips on how to get started.

One thing to note when getting started you should begin by taking an object from your desk or something on the shop floor and create a CAD model. This approach is fairly easy and straight forward. All these guys will talk about orienting the 1st sketch/feature for a part and getting that right. It's different than autocad which you started anywhere and offset lines and built around the 1st line you put down. On a drafting board you never cared where zero was and since autocad is a replacement for a draft board, the concept of zero was lost. In parametric modelers you really want to build around zero or the initial planes. The concept of zero is important to parametric modelers which is different than autocad. 

Most of these intro level books on modeling stop at getting a part oriented about the 3 planes. I recommend that you don't stop there and drive this philosophy all the way to the top level assembly. From the top looking down you should be able to see some type of structure, some organization, some type of pattern. This is very hard to do and requires practice. Many/Most don't do this and it's real a problem.

Taking something that exists and creating something in CAD is fairly easy and a good place to start. Try to maintain some kind of structure between part and various assemblies. You should be fine. At the end of a project you'll feel that you could have done a better job and this is natural. The 2nd time you build something you'll always do a better job.

My problem with parametric modeling is trying to begin with an idea or napkin sketch. Creating this structure that I've talked about is very complicated and difficult to do when creating from a concept. All advanced CAD systems suffer from this and I'm hoping Onshape solves this problem. I think they will. To illustrate my point, in solidworks, how do you insert a new part in an assembly? Do you use the assembly coordinates or the part coordinates? It's not easy and it should be. Starting with a blob and dividing it down into it's parts is very difficult to do with today's technology. Yet this is what I want. Designing something from a concept is difficult so begin by designing something that exists, something that you can hold. Work on something that's an assembly and learn to control this structure.

Anyway, that's how I would begin,

billy2

I feel like I've hijacked this thread. Something I always tell people who ask me how to get started with CAD "Learn geometry 1st and forget about learning CAD". All CAD systems build geometry and understanding these entities is universal and the foundation for all CAD systems. I guess it's the beginning.

CAD Entities:
1. points
2. lines
3. arcs
4. conics
5. splines
6. surfaces
7. trimmed surfaces

That's only 7 things to learn, not too bad.

matthew_menard

The only thing that I would add to that list, @billy is a second category of relations and how relations and dimensions tie all of those entities together and drive overall geometry.  I'm trying to get the two guys running the CNC machines in our shop more comfortable with Solidworks.  The only items I've had a chance to cover so far from your list are points, lines, and arcs, but with the addition of how relations (in Solidworks terms, constraints in OS terms) drive geometry along with dimensions.  I'm really trying to drive home how setting up a good base sketch for your work can save you time and aggravation down the road. The temp who's place I took here made a bunch of models with SO MANY DIMENSIONS in the sketches, instead of using relations for items that were intended to be the same size (just as an example). 

Even though I have been doing 3d modeling / drafting for fifteen or so years, I love reading how other people accomplish even mundane tasks.  I always try and keep an open mind to the approaches I take to getting my job done and try new approaches that I see others take to see if there is any benefit on my end.  Internet forums have been some of the best resources I have turned to over the past few years.  I can look back at some of the projects I did when I started here only three years ago and say "what was I thinking?".

Best of luck Russell, just a warning though.  Once you bite the apple of parametric modeling, you won't want to go back to AutoCAD ever again.

peter_hall

I would suggest joining at www.infiniteskills.com for $25 dollars a month there is a wealth of good video learning. I especialy liked Dean Kerste on Solidworks. Video learning is a good way of seeing what you can do. I did this myself for 6 months and it helped a lot. Then when I wanted to try it for myself the cost of Solidworks was not on , thankfully I found Onshape

russell_tucker

Awesome replies everyone, lots of good information. These forums are a wealth of info and I will definitely be spending time here reading and trying things that are discussed, along with the other reading and videos that were mentioned.

Thanks for the help!