3D CAD and Model Engineering

[rleete]

I use Draftsight at work for 2D layout stuff (plant layouts) that doesn't need 3D. It is functionally the same as AutoCAD. Very nice package for those that don't need 3D.

 

[doc1955]

I use Catia, NX6,and Auto cad at work and have also used Solid Works which is similar to NX6 but in my opinion is dumbed down a little. I prefer NX6 and second would be Catia but both are spendy for a home shop. For CAM side I use either NX6 or FeatureCam and I prefer FeatureCam we have had that where I work for at least 15 years ore more. I design tools for a living mostly Cargo systems tools and some military things. I have been doing CAD in one form or another for a long time seems like forever. If we have any other NX users and they are attending the UG World Conference in Dallas we could meet up I have been asked to attend for our company.
I did start out designing tools on the drafting board many years ago I had the pleasure of designing tools and then building them in the sho back then. Would I go back no but I do believe beginners should learn on the board anyway to understand how a view is created through fold lines and such then Cad will come even easier when you know whats going on behind the scenes.

 

[mikegw1961]

I have been trying to teach myself Alibre for the last couple of weeks. Taking the time to learn this as I cannot get into my Worksop (shed) as i am having to look after my mum at the moment.

I have finally finished drawing and assembling the Vega V Twin

This could be the next project if I ever finish the Nemett Lynx I have started.

This was drawn 2x scale and I think I have it correct now. There were some missing dimensions in the original article.

Need a another project to draw now. Thinking of a straight 4 IC engine. Need to find some drawings


Mike

 

[popnrattle]

I prefer 2-D because it is faster for me, although I can draw fairly well in 3-D and do so because it makes my 2-D parts look cool and sometimes I need to make my parts in the prototype machine.

I guess its hard to break old habits I been using since '73(high school drafting board and T-square).

The youtube link is for the parts of the 6 cyl. rotary air engine.

[ame="http://www.youtube.com/watch?v=JqfgLoUedkM"]http://www.youtube.com/watch?v=JqfgLoUedkM[/ame]

The sectioned head of the 2.22 cu. in. mini hit-n-miss engine is the attachment. Later, Rick.

 

[lohring]

I'm finally starting to learn Alibre. It's far from intuitive and very difficult for the kinds of shapes I need to model. I think I can model the various important characteristics of surface piercing propellers, but two stroke engine transfer passages are a lot harder. The first picture shows a propeller. The cylinder I'd like to model is the other pictures. The 3D model of the transfers may be a scan of the core patterns. Some type of lofting procedure through a series of sections set at a series of angles along the passage is the only way I can think of to draw the passages. Any other suggestions?

Lohring Miller

 

[mrehmus]

Lohring,
Alibre isn't really great at modeling complex contours. It can be done but there is a 'sister' program you should take a look at, MOI or Moment Of Inspiration. www.moi3d.com should get you there. I bought in to it when it was first introduced but haven't had time to play with it much. Another program (more expensive) is Rhino that should do some bits a pieces for you.

I suggest you look at making complex passages in a slightly different way. First make the engine cylinder, leaving the bypass passage area as a solid. Then make a negative of the passage (separate model). Then use Boolean subtract to create the passage in your cylinder. Somehow, looking at the passage as a negative of the final bit is easier than working in the cylinder model (for me). Of course, a Boolean subtract object is actually a lump that looks like a solid of the passage.

Contact me off line if you have questions about this process. We've used the Boolean technique on models of V-8 blocks, complex engine bases, etc.

 

[Tin Falcon]

Mike interesting program look more like a computer sculpture program than for machine design.

I have alibre.
Tin

 

[lohring]

I looked at MOI, but decided to try Bonzai3D. All these programs have a steep learning curve. The method I used to generate propellers in Alibre doesn't seem to work with Bonzai. However, the main reason for something new was transfer passages, so I'll start working on that. I'll try subtracting the passages from a solid. The way I was planning to make the cylinder with conventional methods was to build the passages and cover them with sheet wax. That way I could make the outside mold. A mold of the passages could be used to generate the cores. See the picture for the sand cast core molds a commercial foundry uses.

The main reason for 3D modeling is the promise of 3D printing. So far even commercial methods haven't been good enough for propellers. I plan to have a test propeller laser sintered in stainless steel to see how that works. I keep hoping that something like PLA from a low cost printer could be burned out, but the consensus seems to be that its expansion would damage the investment. I'm sure commercial manufacturers could make a good casting, but the cost will be high. In any case, I need a 3D model first.

Lohring Miller