JD Mather Posted June 9, 2014 Share Posted June 9, 2014 JDM: .... if after doing this I am still stuck I will upload the .zip to my website FTP and post a link... So far I hear that I have to write my own script in C# to do this? SEANT: I didn't realize the cross shape on the bent piece was not symmetrical... Don't bother - based on previous responses I suspect you just need to develop more experience before you are ready for anything I might add to the discussion. Would be interesting to see your "finished" design though. Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 9, 2014 Author Share Posted June 9, 2014 I had 3 people tell me so far that AutoCAD [3D] is the wrong tool to use for what I want to achieve and I should switch to Rhino, Solidworks or CATIA - thanks for making it clear that it's the lack of experience rather than software ability. One problem is that I didn't see any tutorials that model the kind of geometry I am after - seems it's all basic stuff. I will take a look at 3D tutorial listed on this site. Other than that - can someone recommend a book or DVD I can get from Amazon, etc on 3D modeling techniques I need to know? I will post pictures of final assembly after the parts get back to me from CNC shop - maybe another month or two depending on what other trouble I get into with AutoCAD. My biggest fear is they say "we can't do that because you have too many small pieces" and I have to spend another quarter of a year re-modeling using some kind of different technique to make it suitable for CNC. Quote Link to comment Share on other sites More sharing options...
ReMark Posted June 9, 2014 Share Posted June 9, 2014 (edited) Most tutorials are going to cover the basic use of each command and do so while avoid the use of complex models. What is it that you want to learn that you can't seem to find? Have you tried searching for videos about solids editing? Edited June 9, 2014 by ReMark Quote Link to comment Share on other sites More sharing options...
JD Mather Posted June 9, 2014 Share Posted June 9, 2014 I had 3 people tell me so far that AutoCAD [3D] is the wrong tool to use for what I want to achieve and I should switch to Rhino, Solidworks or CATIA - thanks for making it clear that it's the lack of experience rather than software ability. Autodesk Inventor is the Autodesk product equivalent of SolidWorks. CATIA is wayyyyy overkill for this simple geometry... ...and this is very simple basic geometry in anyCAD. (AutoCAD included, although I would use Inventor or SolidWorks if I had a choice.) Edit: OK, the word I really want to use is trivial. My biggest fear is they say "we can't do that because you have too many small pieces" and I have to spend another quarter of a year re-modeling using some kind of different technique to make it suitable for CNC. Part of the reason why I elected to withdraw from this thread - I'm not sure you really know what you want. Design for Manufacturability should occur now, up-front, not after sending to shop. Make a print of the current design and take a walk out the shop floor and talk to the guys (or gals) who will be making the part. Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 15, 2014 Author Share Posted June 15, 2014 I've poured a lot of time and effort into making this part and restarted from scratch 3 more times, but unfortunately I got zero progress. I tried to model it additively, subtractively, with lofts, with surfaces, with meshes, with polylines, intersective booleans, nothing works. Hoping someone here can shed light on how to do this. Since I already spent 20 hours on it just this week I don't care if it's the "fastest" way, I just want "any" way. Last method I tried is additive booleans with polylines. Basically put the original geometry on a frozen layer, then built "perfect" polylines around it, making sure all sizes are exact and all polylines are coplanar for each face. When I got to the second pair of lofts, AutoCAD said my geometry was not co-planar. This means red face in diagram and blue face cannot be extruded, and lofting them creates a surface instead of perfect solid. I can't understand how that's possible because every time I created a loft face using 3d polyline, I chose just one vertical edge by tracing an existing vertical edge and copying it twice. After creating the top edge, I copied it to the end of vertical edge to create bottom edge. If that doesn't guarantee orghogonal edges, what does? Attached is DWG of isolated model in the process of being built and a diagram of how I got there. help.dwg Quote Link to comment Share on other sites More sharing options...
ReMark Posted June 16, 2014 Share Posted June 16, 2014 What is the object supposed to be? A quick look at your drawing reveals what appears to be a lot of extra (perhaps unneeded?) geometry. Could you explain what you were attempting to do? Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 16, 2014 Author Share Posted June 16, 2014 I am approximating Max Exoskeleton forearm from photo references. The bolt holes are 6mm and the length is what's in the drawing, the rest is open to interpretation. I am not trying to go screen-accurrate, rather a custom design that "looks better to me". So, I restarted from scratch once again and I see that AutoCAD is failing to snap my geometry properly. I set UCS to a flat plane that I want to constrain all my drawing to. Then I start drawing each line from the endpoint of previous line, and make sure it stays on the plane. In this case, I begin with one 3D object that all lines connect to, so I make sure the start points snap to 3D corners. Then I use the 2D rotate command to rotate the lines the way I want to after I create them with exact length. This further is supposed to make sure the lines are on the right planes. When I copy or connect them to each other, I always make sure to type "endpoint" in the command prompt, find the intersection/endpoint and wait until mouse-over tip says "endpoint" then plot the line... Then WHAM! They don't align: Can you explain how to handle this situation? Assuming I want the geometry to go very much the way it looks from my DWG files. The latest one even has all important dimensions rounded to .5 millimeter, because I submitted the drawings to CNC shop and settled on .5 mil as tolerance for manufacturing. The two slanted polylines that connect to green 3D object both don't even extrude let alone loft, for this precise reason (bad snap?) UA fold 1.dwg Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 16, 2014 Author Share Posted June 16, 2014 These GI renders may help you visualize "what I'm going for", if that makes sense. I want the bent piece to have a faceted edge near the base of it, because I like the way that face looks. That's the one that has a shorter outside edge than all the others. Then I also tried to maintain the same thickness, but couldn't do it on the first iteration. I will be trying to fix that this iteration. Quote Link to comment Share on other sites More sharing options...
ReMark Posted June 16, 2014 Share Posted June 16, 2014 Is this custom design supposed to fit any particular person? Other than "guessimating" dimensions based on photographs have you done any mock ups using everyday materials that one could easily acquire? Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 16, 2014 Author Share Posted June 16, 2014 Yes, I estimated using 2D paper on cardboard cutouts, with various pieces bent as needed. I printed everything 1:1, so the sizes in all drawings are designed to fit me. Some parts I change as I go from 2D from 3D, this one changed gribble detail and certain angles but of course remained the same length and roughly the same width. I think my question has more to do with why AutoCAD won't let me plot a bunch of simple lines the way I want to. There must be something I need to turn on or turn off to make this happen, because it's hard to believe that I would be sitting there 5 hours at a time and end up with 6 small solids and then it won't let me make 7th because something is wrong at a microscopic level. Quote Link to comment Share on other sites More sharing options...
ReMark Posted June 16, 2014 Share Posted June 16, 2014 (edited) The mockups are pretty good as far as they go but I don't see where exactly you handle things like changes in thicknesses of material. Maybe it is the angle at which the photo was taken. This task seems more suitable to Inventor rather than AutoCAD. And you are going to pay to have these parts manufactured as "one offs" on a CNC machine? Sounds fairly expensive. Have you laid any of these parts out in orthographic projection (top, front and side views)? Have you considered breaking down complex parts into their basic components, modeling them separately, then combining them using the Align and Union commands? Edited June 16, 2014 by ReMark Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 16, 2014 Author Share Posted June 16, 2014 #1: As JDM suggested, this geometry is not complicated enough to necessitate a switch to Inventor. Since I started with AutoCAD, I would rather figure out what I am doing wrong than switch to different software. It's like if you keep running stop signs it means you need to learn how to drive rather than get another car...? #2: For Manufacturing, I am expecting a $1k quote for this part, so of course 2k for both upper arm pieces, which is indeed steep. But where there is want, there is a way I will sell my lego collection and buy a milling machine, then prioritize the parts and manufacture easier ones myself. #3: when I work on geometry I worked in only one view, but just recently switched to two views to make sure stuff lines up. Quote Link to comment Share on other sites More sharing options...
ReMark Posted June 16, 2014 Share Posted June 16, 2014 (edited) OK....AutoCAD it is. Had you given any thought to buying a 3D printer and doing both the design and printing yourself? My concern would be you get a piece back and find out it doesn't fit up correctly and a design change is in order. Now you are stuck with a piece that you can't use and you are out a whole lot of money too. When I referred to different views I meant separate 2D views of which you would have the standard three (top, front, side) and any additional views required (ex. - bottom). Have you ever taken a drafting class? You might inquire of JDM whether this project is doable using meshes. I think we have a bit of a conundrum here. You know in your mind what you want the pieces to look like but don't know exactly which AutoCAD command or combination of commands would produce the best results. On the other hand some of us here have plenty enough experience with most all of the commands that would prove beneficial to you but we don't have a clear enough picture of what it is you are trying to do. This problem is not insurmountable it's just going to take a little longer that's all. Please bear with us as we shall bear with you. Does that sound reasonable? Edited June 16, 2014 by ReMark Quote Link to comment Share on other sites More sharing options...
JD Mather Posted June 16, 2014 Share Posted June 16, 2014 I am approximating Max Exoskeleton forearm... The part you have been working on looks like shoulder area to me? Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 16, 2014 Author Share Posted June 16, 2014 It was a late night typo, I meant Upper Arm - sorry. There is a separate part for Shoulder Blade which I call Shoulder: Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted June 16, 2014 Author Share Posted June 16, 2014 I will get back to you guys with a wireframe net that has every single dimension called out. I simply can't think of anything more detailed to define the geometry of the part I want. Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted July 20, 2014 Author Share Posted July 20, 2014 I switched to Inventor because some parts down the road cannot be easily done in AutoCAD, as a result I am re-doing this part in Inventor. I never did figure out how to do it in AutoCAD after sinking another month into it. Every single dimension is called out as promised, and all constraints are implemented. I also kept geometry as simple as possible with number of operations and did my best to organize the model tree. My question this time is: how do I make "sharp" bends instead of radius bends? I used the Bend feature to make 5.5mm radius bends, but I need the outside edge to be sharp. I tried to do the same by using rotated planes and extrusions to manually create the bends, but then couldn't figure out how to connect one extruded profile to another, because the arrangement of slopes on the sides of the bend was complicated and confusing. You can even see in this screenshot below that when using regular Bend feature Inventor creates some crazy geometry to make it happen: So how do I do the same thing, but with sharp bends, and presumably manually since there is no command to handle sharp bends? Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted July 20, 2014 Author Share Posted July 20, 2014 Attaching the IPT for Inventor to this post. UpperArmShoulderBenti2.zip Quote Link to comment Share on other sites More sharing options...
JD Mather Posted July 20, 2014 Share Posted July 20, 2014 I switched to Inventor... I would have posted this to the Inventor forum with a hyperlink back to this thread for reference. http://www.cadtutor.net/forum/forumdisplay.php?32-Autodesk-Inventor Quote Link to comment Share on other sites More sharing options...
guitarpirate Posted July 20, 2014 Author Share Posted July 20, 2014 Thanks will do! Quote Link to comment Share on other sites More sharing options...
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